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Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research (2022)

Chapter: APPENDIX E: Work Zone Intrusion Technology Case Studies

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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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Suggested Citation:"APPENDIX E: Work Zone Intrusion Technology Case Studies." National Academies of Sciences, Engineering, and Medicine. 2022. Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research. Washington, DC: The National Academies Press. doi: 10.17226/26626.
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131 APPENDIX E: Work Zone Intrusion Technology Case Studies 1. AFAD 2. Mobile barrier 3. ATMA 4. Smart work zone (queue warning system, DMS, and speed enforcement) 5. IAS 6. Wearable lights

132 1. AFAD Technology Description and Functions Automated flaggers, commonly referred to as AFADs, are portable equipment stations used as a TTC device to control access to a roadway work zone. The equipment commonly includes signal lights to alert motorists to stop or proceed, plus a mechanical gate that prevents proceeding into the work area (http://noflaggers.com/Page22/Default.htm). An audio system (e.g., warning horn) is also included to provide audio warning in case a vehicle improperly moves forward into the work zone during a stop signal. The gate is mechanically operated. The stop/go light sequencing along with the lowering and raising of the gate are programmed when the system is set up to accommodate the duration of the safe movements through the work zone. The entire system operates independently without human assistance and monitoring. Automated flaggers are commonly used for short-term or intermediate-term lane or road closures, and placed in the roadway shoulder adjacent the travel lane at the entrance to the work zone. The Automated Flagger AF-100 (http://www.noflaggers.com/automated_flagger_overview.html) is an example of an AFAD and described in this case study to provide guidance for this class of technologies. The AF-100 is a portable traffic control device that meets the 2009 FHWA MUTCD Section 6E.04 specification. The device contains a red/yellow lens system along with a mechanical gate arm, and can be used in a single- or two-trailer operation. The combination of the red/yellow signal lights and gate arm is visible to oncoming traffic to instruct the motorists when it is safe to proceed into the work zone. Figure E1.1 provides a graphical view of the AF-100 and its components. Figure E1.1. Side view of AF-100 signal trailer (Ullman et al. 2010)

133 The manufacturer’s instructions for placing and setting up the AF-100 system near the work zone include the following steps: • Place sign unit at desired location. • Set up proper cones and signs per work zone regulations. • Retract hitch in and extend outriggers. Next, extend the jacks. The jack pad should have positive contact with the ground. • Raise mast. • Power on the sign units; the gate arm motor will initiate momentarily. • Power on the controller, and verify communication between controller and sign units. • Extend gate arm to desired length; this step may be easier when the sign is in the “SLOW” position. • Repeat with second sign unit if used. Technology Applications, Set Up, and Use AFAD systems should be operated by qualified flaggers who have been trained in the use and operation of the type of AFAD system to be used for the work zone. At no time should the AFAD be left unattended while not operational. The flagger operator should not actuate the AFAD’s right- of-way display until all oncoming vehicles have cleared the one-lane portion of the work zone. The following guidance should be followed for AFAD systems that are controlled with one flagger/operator (NCDOT 2009): • AFAD systems no more than 800 feet apart. • Both AFAD units should be located such that they both can be seen at the same time from the flagger/operator position. • The flagger/operator should have unobstructed view of approaching traffic in both directions from the flagger/operator position. • The operator should be positioned off the roadway between the AFAD units. The following guidance should be followed for AFAD systems that are controls with two flaggers/operators (NCDOT 2009): • AFAD systems may be more than 800 feet apart. • May be used when: o Site conditions prevent both AFAD units from being seen at the same time due to curvature of road or difference in the vertical alignment of the road. o One operator cannot see traffic clearly from both directions. • AFAD operators may control traffic at side streets or driveways. During this activity, both AFAD units must continue to be within clear sight of the operator during this work activity. If one or both AFAD units becomes inoperative, the operator(s) must be prepared to (NCDOT 2009):

134 • Immediately replace the unit or system with the same type of AFAD model. • Revert to flagging using a human flagger. • Terminate all construction activities requiring the use of an AFAD until the entire AFAD system is operational again or qualified human flaggers are available and in place at the flagging station. The following steps should be taken when the work interrupted for 30 minutes or longer (NCDOT 2009): • Each AFAD unit should be placed in the “Caution” mode. • The AFAD units should be removed from the travel lane and placed 5 feet away from the edge line of the shoulder with the gate arm in the upright position. • Two cones should be placed adjacent and upstream of each AFAD unit, and all signs associated with the AFAD should be removed or laid down except the “Road Work Ahead” sign. The locations of the AFAD units and the operator relative to the active work area are important considerations when utilizing AFADs. The AFAD controller is set to paired mode where the remote user has access to both AFADs. The paired mode of operation prevents the AFAD from going into the slow position. In some cases, and when allowed by state laws and regulations, a single AFAD unit may be used in combination with a human flagger. For this case, the AFAD controller is set to single mode and allows the flagger to operate only one sign unit. The operator is in charge of manual control of traffic at the other end of the work zone. AFADs may be used for traffic control at roadway intersections. At 4-way intersections in which the roadways intersect each other at a perpendicular angle, the AFAD controller mode is set to independent mode. In this mode, both AFAD sign units may go to the amber (slow) position. When such a layout is used, caution must be taken while replacing the battery in an AFAD. During batter replacement, the AFAD defaults and reverts to stop mode. This feature is a safety default, and after the battery is replaced, the operator has to re-enable the independent mode of operation. When the work zone is very long, or there is a sharp horizontal cure, hill, or vertical change in grade between AFAD units, clear sight distance between the operator and AFAD units may not exist. In this case, an extra operator is needed. This setup is used when the distance between the AFAD units is beyond the line of sight of the operator or a clear view of traffic is not visible. AFADs may also be used during roadway maintenance activities and encroachment permit work. Traditional flaggers are typically used for short-term work zone operations involving culvert, drainage, or other maintenance work. In interviews with Caltrans staff, those interviewed suggested that AFAD systems be used for longer term stationary work zone activities, such as grinding and paving a 5-mile section of roadway.

135 Technology Adoption The decision to adopt one or more AFADs for use in work zone flagging operations should include consideration of factors related to the technology and expect use cases. Caltrans staff interviewed preferred AFAD units that are light weight so that they can be easily transported and oriented, and have a sturdy gate arm that can withstand the repetitive up and down movement and operate in heavy winds. Those interviewed also recommended that the AFAD should be motorist compliant, i.e., it is easily understood by motorists and does not cause confusion about what action to take. The AFAD system should be capable of being relocated as per the traffic conditions. The device should also meet the physical display and operational characteristics described in FHWA’s “Revised Interim Approval for the use of Automated Flagger Assistance Devices in Temporary Traffic Control Zones” (IA-4R) (Caltrans, 2006). Ambient mobile or other radio transmissions or adverse weather conditions should not affect operation of the system when in use. In addition, the unit should not violate FCC regulations, and the radio frequencies utilized should be appropriate for AFAD-type applications (NCDOT 2009). Pilot testing of AFAD units enables informed decision-making and technology adoption. The pilot testing should be performed on work zones that are representative of its future use. For example, Caltrans employees interviewed indicated that Caltrans experimented with a traditional style AFAD system where the stop/slow paddle rotates around its length with both red and yellow lenses and an audible alert system. Where lane closures on two-lane conventional highways with reversible traffic control systems are implemented, the AFAD provided immediate effective use on the Caltrans projects when used in accordance with the latest AFAD guidelines to enhance work zone safety. Pre-planning and Implementation Plan Technology use commonly involves some type of pre-planning prior to the work operation and the development of an implementation plan for the technology. This documentation is included in project documents, contracts, and communications. In its effort to identify prospective AFADs, Caltrans employees interviewed indicated that Caltrans decided to develop specifications for a specific style of AFAD to be used on its projects. An AFAD was to be used on a project depending upon the number of road users or advance detail plans (ADP) level. In the future, the goal was to provide an AFAD system to each and every crew. Strategic placement of the AFAD system was based on crew data. Evenly distributing the AFADs throughout the large numbers of crews is seen as an action plan. Use of the AFAD is based on the safety data and/or depending type of work (e.g., paving a 5-mile section of roadway). On current projects, when the contractor submits a request for the use of AFADs with flagging operations, the resident engineers along with project managers and district traffic manager will review and approve AFADs immediately where feasible. On the projects that are currently in the design phase, the constructability review serves a basis where the design engineers call for the use of AFADs when viable. This process includes the addition of AFADs in bids and plans,

136 specifications and estimate (PS&E) packages. An exception to using an AFAD on a qualified project would be approved by the district director and is documented in the project files. Training and personnel resources are commonly required in support of AFAD implementation. In Caltrans, for example, as per the California MUTCD, AFAD operators need to be trained as a flagger in order to step in and take control manually when the AFAD fails or malfunctions. AFAD operator are qualified flagger who have been trained and approved by the manufacturer to operate the specific device (NCDOT 2009). The focus of the training includes proper installation, remote control operation, central control systems and maintenance of the AFAD device. The training should take place off the project site where training conditions are removed from live traffic. Records of the training should be created that include the names of the authorized trainer, the trainees, the device on which they have been trained and the date of the training. There should be no deployment of the AFAD until the operator has received the certification and documentation (NCDOT 2009). To ensure that the AFAD system’s wireless communication links are working properly, the operator should continuously monitor and verify proper transmission and reception of data used to monitor and control each AFAD. When the AFAD is not in use, it should be removed from the roadway. If possible, the AFAD unit should be stored offsite or behind a barrier or guardrail, or moved to an area at least 15 feet away from the shoulder lane edge of the roadway. Ownership and operating costs should be considered as part of technology adoption. For the AFAD system consisting of two AFAD units, cost estimates have been developed for rental of the units for a period of 90 days (NCDOT 2009). The cost of each unit was determined for their operation at any time during the life of the project. No estimate was made for the operator or operation, relocation, maintenance, removal, or use of flaggers during the times when the AFAD was inoperative as these items are considered incidental to furnishing, installing, and operating the AFADs. Payment for AFAD systems was made on the following schedule (NCDOT 2009): • 25% of the unit bid upon placing the system in service • 50% of the unit bid when the project is 50% complete • 25% of the unit bid when the project is 90% complete Observed Technology Impacts and Effectiveness The AF-100 offers unique opportunities for enhancing project performance and outcomes, including: labor savings, higher visibility, removal of humans from the roadway, and reduction in the possibility for human error liability (Ullman et al., 2010). According to Caltrans employees interviewed, an AFAD performs better than a traditional flagger system as it is motorist compliant. The confusion whether the motorist should either stop or proceed ahead is eliminated when the red/yellow lens AFAD system is used. In comparisons with human flaggers, motorists were found to be distressed when the traditional flagger with slow/stop

137 paddle was used. This feeling was eliminated with the use of the red-yellow style lens with gate arm. Those Caltrans employees interviewed also indicated that AFADs are easy to move around when two AFADs are attached to a single pickup truck. The slow/stop paddle was eliminated and replaced with red/yellow lenses which are familiar to a large section of the population from all over the world; this feature enables motorists to understand the stop/slow functions. The traditional flagger unit was operated manually by a worker or a dedicated operator. Since the use of an AFAD system, the whole unit can be operated from a remote location which is in the line of sight of the AFAD unit. In tests of the AFAD units, minor incidents and close calls were experienced, and those incidents have been the focus for improving worker safety. The Caltrans employees interviewed stated that some AFADs have been hit by vehicles, either the gate arm or the central unit, when the vehicles were trying to go around the work zone. In these cases, the automated flaggers were replaced by human flaggers and/or traditional flagger units, which were kept as a backup option just in case the AFAD was inoperable. Apart from using the AFAD, potential countermeasures have been suggested in several work zone areas associated with one-way flagging operations, such as the advanced warning area, at the flagging position, and in the active work area. The following potential countermeasures at the flagging location can be adopted in the advanced warning area where the approaching driver fails to recognize stopped or slowed traffic (Andrew and Bryden, 2013): • Use of temporary transverse rumble strips to produce audible and tactile warnings. The researchers found that over 8 mph reduction in speeds occurred 600 ft upstream of the flagger when four sets of temporary transverse rumble strips were applied between 500 and 1,500 ft upstream of the flagger. • Use of advance warning messages on PCMSs used to warn drivers of an upcoming work zone and slow or stopped traffic. • Use of DSD trailers to inform drivers of the need to slow down and allow them to compare their speed to anticipated speeds of vehicles in front of them. • Provide enforcement (real enforcement agency car along with police officers) in conjunction with these devices or by itself may also reduce the occurrence of intrusions at flagging operations. In addition to enforcement and temporary rumble strips, the following methods may be employed to reduce work zone intrusions at the flagger station (Andrew and Bryden, 2013): • Use closer-spaced or continual traffic control devices along with the transverse traffic control devices/LCDs to improve delineation of the lane closure and prohibit drivers from entering the closed lane. These devices can also be used to block off access to the shoulder to discourage drivers from going around the closed lane through the shoulder. • Provide advance notice of work activity on the PCMSs allows drivers to avoid the work zone, if desired.

138 • Limiting length of lane closures to avoid blocking driveways may reduce delays and thus decrease the potential for drivers to get impatient and try to go around the flagger. To provide further improvement, uniformed officers may be present to guide the traffic flow. • Replace flagger with police officer. • Use AFADs that are portable traffic control systems designed to be operated by a flagger located off the roadway. There are two types: one, uses a STOP/SLOW sign to control the right-of-way, while the other uses red and yellow lenses. Barriers to Use and Limitations to Effectiveness In an interview regarding use in practice, Caltrans employees felt that the traditional flagger unit was heavy and difficult to move around by a worker. An AFAD is highly mobile and can be moved easily via a pickup truck. Hence, the use of an AFAD is considered to be easier. The setup and removal of the AFAD system from one grid to another is accompanied by significant worker exposure to the traffic and is seen as a disadvantage. Those interviewed also indicated that the red-yellow lens light on the AFAD can be difficult to move around by the worker as it is heavy and hence, the use of a pickup trucks was deemed necessary. For a work zone activity such as a crack sealing where the operations are mobile in nature, compatibility of the AFAD to easily move around the work zone without the use of a pickup truck would be seen as a plus point as the AFAD is heavy and difficult to push. In some cases when an AFAD system is used, it may not have an intrusion alarm system to automatically warn workers and motorists of an intrusion. In this case, Caltrans employees interviewed felt that the drawback is that the AFAD remote operator has to push a button manually on the remote controller to sound the alarm. Attaching two AFADs together allows both units to act as one unit so they are easy to move around by hooking them up to a single pickup truck. According to Caltrans employees interviewed, this ability eliminates the need for multiple pickup trucks and/or avoids double the number of trips by a single pickup truck. Caltrans working professionals interviewed recommended an AFAD with wheels which would allow the AFAD to be moved around by a worker alone within the work zone operation. This feature would be something that DOTs would be interested in as it decreases the unit weight and makes it easier to maneuver the AFAD. Recommendations for Use As an enhancement to the AFAD, those employees at Caltrans who were interviewed recommended that other technologies should be used in conjunction with the AFAD. For example, smart cameras can detect vehicle intrusions and any damage to the AFAD. Second, an automated scanning device with LiDAR can keep track of the physical condition of the AFAD and the LiDAR device can project rays of beams along the work zone boundary tip off the alarm when a vehicle breaks the line of sight of beams. Third, use of infrastructure- or pavement-mounted intrusion alert devices (e.g., SonoBlaster, Intellicone, or WAS) which are placed strategically between the AFAD

139 systems is expected to increase safety for the motorists and decrease the number of intrusions that lead to worker injuries and fatalities. The downside of this form of setup that it may prove to be costly and the locations of the work zone intrusion alert devices should be monitored continuously. Portable traffic signals are traffic signals mounted on trailers that can be used to control the right- of-way in a temporary work zone. Communications between signals are bound by hard wiring, a radio frequency transceiver, or by preset timing. This feature proves to be an opportunity to replace the automated flaggers by removing them and protecting them from direct exposure to the oncoming traffic flow and allowing flaggers to operate other critical tasks. The exact timings are necessary for the success of the portable traffic lights. Portable traffic signals are suitable for long- term and short-term work zones as well. The typical applications include: long-term bridge construction, short-term pavement repair, and short-term bridge maintenance (Andrews and Bryden 2013).

140 2. MOBILE BARRIER Technology Description and Functions A mobile barrier is a mobile traffic barrier system used to provide positive protection between passing vehicles and the work area. Mobile barriers serve to prevent intrusions into a work area and therefore protect the workers from vehicle intrusions. Mobile barriers are easy to set up and remove in and around short-term work zones during peak traffic hours. Mobile barriers are useful during both the daytime and nighttime. Some mobile barriers have lighting systems to illuminate the work area and a dynamic message sign attached. A crash attenuator may or may not be attached to provide a cushion against the impact of vehicles from the rear end of the truck. For example, the MBT-1®, developed and manufactured by Mobile Barriers, provides 42 to 102 feet (12 to 31 m) of highly mobile positive barrier protection with minimal deflection (https://www.mobilebarriers.com/media/docs/Mobile%20Barriers%20Products%20and%20Opti ons%20-%200618.pdf). It can be used with any standard semi-tractor with 60 inches (1.5 m) of swing clearance. The barrier can be transported fully set up at freeway speed from site-to-site. It is commonly used with a cabover or day cab tractor. Configured at 62 feet (18.9 m) using one wall section, the MBT-1® drives similar to a semi-trailer. The MBT-1® can be easily reconfigured to the right or left lane closure configuration depending on the end to which the tractor is attached. The MBT-1® features lockable and on-deck storage and can be ordered with integrated electrical power, lights, signage, TMA, crane, and other features. An MBT-1® is available for sale, lease, or rent (https://www.mobilebarriers.com/resources-drivability.html). Technology Applications, Set Up, and Use Mobile Barriers MBT-1® was developed to help improve work zone conditions for workers and the public (https://www.mobilebarriers.com/features-tapered-wall-and-mbt1s.html). It is in essence a portable, self-contained, work zone that simply drives in place much like a semi-truck, and then can be transported off the site as quickly when the work is done. The MBT-1® is designed to provide a safer, better work environment for workers, minimize disruption, improve traffic flows, and allow for reopening lanes more quickly for the public. The MBT-1S®, a shortened version of the highly mobile MBT-1®, is especially suited for the tapered wall sections. The tapered wall sections provide access for the workers to the full lane with only 6 inches of incursion on the adjoining lane. The sections can be used with new and existing barriers. Mobile barrier use is seen especially for highway construction, maintenance operations, utility work zones, and very short-term work zones where fast-flowing traffic is present and the workers have very little to no protection available. The work zone configurations may be setup for long- term or short-term durations. Protection is especially important in transition areas. In Oregon, 40% of the work zone intrusions and crashes occur in transition zone prior to the active work area. These crashes result in driver and worker fatalities, along with impact on social and emotional aspects of the next of kin (Gambatese and Tymvios, 2013).

141 In order to provide protection to work zones, additional barriers are provided between the fast- flowing traffic and the work crew. Positive barriers such as a mobile barrier can provide this additional guard. The MBT-1® provides a wall of steel adjacent to the work area that prevents vehicle intrusions into the work area (Gambatese and Tymvios, 2013). The MBT-1® provides the functions and related specifications listed in Table E2.1 (https://www.mobilebarriers.com/resources-specifications.html). Table E2.1. Details of MBT-1® Configured to 62 ft (18.9 m) With One Wall Section (https://www.mobilebarriers.com/resources-specifications.html) Functions Specifications Modular Configuration • 21ft (6.4m) Platforms: Lockable & on-deck storage, tie-downs, ballast boxes, stands, & hardware. • 20ft (6m) Wall Section: Zero to three wall sections can be used. • Caboose: Movable rear axle assembly (fixed or steerable). Reconfiguration Reconfigurable to protect right or left side of road. Tractor and caboose attach at either end. Accepted/Federal Aid Eligible Accepted/Federal Aid Eligible under NCHRP 350 & MASH for TL-2 and TL-3 for use on the National Highway System. Integrated Power 10K generator with 120/240V power outlets throughout barrier. 12/24V batteries and solar. Work Lighting Long-lasting, high lumen work lights for night operations. Signage Matrix board (with radar) or arrow board. Hydraulic lift. Solar, battery pack, & generator power. TMA TL-2 or TL-3. Examples of mobile barrier application and use are available in a variety of situations. For example, ODOT employees interviewed indicated that, in Oregon, two mobile barriers were used by a bridge crew on a highway road project. The crew worked on two joints at a time and figured out a way to use two mobile barriers, one at the active work area and the other in an efficient place nearby. The second mobile barrier was used around high-risk curved roads located before the bridge. Use of the MBT-1® is recommended in a variety of roadway settings by the manufacturer (https://www.mobilebarriers.com/resources-mutcd-drawings-guidance.html). The recommended settings allow the mobile barrier to be used in work zones within a particular state’s Design Standard Indexes. The application notes are as follows (https://www.mobilebarriers.com/resources-mutcd-drawings-guidance.html): • The MBT-1® is located at the beginning of and/or within the work area and the channelizing devices adjacent to the MBT-1® are not required.

142 • The traffic face of the MBT-1® maybe flush with the edge of the adjacent travel lane. • The MBT-1® proceeds or is relocated downstream within the designated work area, channelizing devices shall be placed at the required spacing from the end of the tape in advance of the designated work area along the appropriate longitudinal line to the MBT- 1®. • The MBT-1® may replace the advanced warning (AW) vehicle when the work area is on the shoulder. • The MBT-1® may replace the shadow (S) vehicle when the work area is in the travel way. • The MBT-1® may replace the shadow (S) vehicle located in the lane where the work is occurring. • The MBT-1® may not be placed in a closed lane between two open lanes. The non-barrier side shall be adjacent to a closed lane(s), shoulder or median. States have used mobile barriers for different types of work operations. In Minnesota, according to the MnDOT employees interviewed, mobile barriers have been used on an approach panel type work zone activity. Maintenance crews participate in a number of activities that vary greatly in type of work performed, duration, crew composition, and equipment used. In Oregon, a mobile barrier has been used for work zone activities that involve surface, drainage, traffic services and structural operations. The following list indicates the general maintenance activities for which ODOT prefers to use a mobile barrier (Gambatese and Tymvios, 2013). • Surface – minor and major road surface repair, deep base repair, pavement sealing, concrete repair and crack sealing • Shoulder – shoulder rebuilding/blading and erosion repair, and sweeping/flushing • Drainage – ditch cleaning and reshaping, culvert and inlet cleaning/repair, channel maintenance, water quality facilities, and horizontal/vertical drains • Roadside and Vegetation – mowing, spraying, brush mowing/cutting, litter pickup, and landscape maintenance • Traffic Services – stripping, pavement legend marking, sign installation and maintenance, traffic signal/illumination/flasher/beacon/delineator/attenuatormaintenance, incident cleanup and repair, guardrail/barrier maintenance/repair • Structures – bridge maintenance/repair, structure painting, drawbridge operations, and graffiti removal • Snow and Ice – snow removal, sanding, winter road patrol, anti-icing, and de-icing • Extraordinary Maintenance – emergency maintenance, slide and rock fall, sinks and settlements • Other Direct Maintenance – snow-pack maintenance, road patrol, contract maintenance • Non-Direct – agreements, training, etc. • Operations and Other Special Programs Table E2.2 lists the work operations and types of work activities for which ODOT anticipates using the mobile barrier in the future (Gambatese and Tymvios, 2013).

143 Table E2.2. Anticipated ODOT work activities for mobile barrier implementation Work Operation Type of Work Surface • Minor/Major Surface Repair • Deep Base Repair • Concrete Repair • Crack Sealing Drainage • Minor Culvert and Inlet Cleaning • Minor Culvert and Inlet Repair Traffic Services • Pavement Legend Marking • Major/Minor Sign Installation Maintenance • Traffic Signal Maintenance • Illumination Maintenance • Flasher/Beacon Maintenance • Guardrail/Barrier Maintenance/Repair/Clean • Attenuator Maintenance Structures • Bridge Maintenance • Bridge Repair • Structure Painting ODOT and MnDOT employees indicated that, since a mobile barrier is a trailer, the DOT needs to provide a semi-truck cab to transport the mobile barrier to the work area. For the MBT-1®, the manufacturer sells the mobile barrier alone. In addition to the traditional equipment and tools that the crews are equipped with, and that are required by the standards and guidelines, ODOT currently owns and operates a Quickchange Movable Barrier System that uses CRTS blocks. Use of the additional equipment shows promising results as per the projects in the Portland, Oregon area (Gambatese and Tymvios, 2013). Technology Adoption For ODOT, those ODOT employees interviewed mentioned that cost and the time constraints were important critical decisive factors of concern when the budget available to be spent on work zone technologies was considered. Cost and time are also considered when determining whether to deploy a mobile barrier on a project. When deciding whether to adopt and use a mobile barrier, the following decision criteria and concerns are suggested by the manufacturer based on Material Development by ATSSA for the FHWA Work Zone Safety Grant Program (https://www.mobilebarriers.com/resources-mutcd- drawings-guidance.html): • There is limited time as it relates to work hour restrictions, setup and removal, productivity, work area access, transportation routes, and removal and storage of the device. There are limited escape areas, such as in tunnels and on bridges. • There is a need for positive protection for exposed work hazards or during night work.

144 • Where deflection can be accommodated – steel barrier deflects over 5 feet if anchored at the ends only, and minimal deflection can be achieved for at least one type of system where the steel barrier is anchored approximately every 33 feet. Generally, deflection may occur in the range of 6 to 8 feet when impacted by a full-size pickup truck. Steel barrier is more practical for short-term projects than for short-duration work zones. Highly mobile barriers typically experience minimal deflection. Caltrans has developed and patented a mobile barrier is calls the Balsi Beam (https://www.workzonesafety.org/files/documents/database_documents/balsi_beam.pdf). The Balsi Beam the mobile barrier system uses hydraulics to alter the length of the barrier and switch the barrier from one side to the other (left/right) (http://highways.dot.ca.gov/mobile_work_zone_barr/index.htm). Crash testing of the MBT-1® was conducted by the vendor where the MBT-1® was crash tested with head-on collisions by a Ford F110. During the test, the barrier moved just inches away from its initial location as a result of the impact (Gambatese and Tymvios, 2013). The MBT-1® meets the following crash test standards (https://www.mobilebarriers.com/resources-mutcd-drawings- guidance.html): • NCHRP Report 350 and MASH Test Level 3. • Equipped with an Energy Attenuator that meets the requirements of NCHRP Report 350 or MASH Test level 3. Prior to adoption on its projects, ODOT conducted a series of tests of a mobile barrier to evaluate its performance in different construction and maintenance project/activities. The mobile barrier was evaluated based on the following performance metrics (Gambatese and Tymvios, 2013): • Time required to set up during the start of the use and takedown the system by the end of the routine • Limitations/enhancements to work operations by the MBT-1® trailer • Worker safety and Safety perception observed by the ODOT staff • Worker productivity while the MBT-1® was present during the work activity • Motorist safety and safety perception by the road users • MBT-1® system performance based on project/site attributes • Transportation to/from work zone. In the ODOT study, data was collected through interviewing workers, observing and timing worker movements, recording worksite conditions and attributes, recording work activities undertaken, observing motorist behaviors, measuring motorist speeds through the work zone, and recording and timing movements and performance levels. Similar evaluations were conducted on project sites where a similar fashion of traditional countermeasures was undertaken. To solicit input from motorists, the researchers planned to work with ODOT to set up a webpage or distribute emails to ODOT staff to provide input regarding perceived effectiveness while using the mobile barrier. Due to a low number of participants, an evaluation of the mobile barrier was conducted in the laboratory using a driving simulator depicting a typical work zone set up with a mobile barrier (Gambatese and Tymvios, 2013).

145 Pre-planning and Implementation Plan Several planning issues have been identified by those DOT personnel who have used a mobile barrier. Based on input from the MnDOT employees interviewed, the following factors and recommendations should be taken into consideration when deciding when and where to utilize the mobile barrier: • The overhanging beam in the mobile barrier may require the workers to close two lanes instead of one lane if the lanes are narrow. • The TMA is used as a supplement along with static lane closure as a means of positive protection to prevent a head-on collision with the vehicle. • A mobile barrier plus cones may be used depending upon the project work. • The TMA along with the mobile barrier is placed partially on the road and in the shoulder. • When equipped with an arrow board, the arrow board allows drivers to know that a lane change is required. One of the aims of the ODOT research study was to identify the use of mobile barriers by other state DOTs through an online survey of all the 50 state DOTs across the U.S., plus the Canadian Provinces, and Washington DC DOT. The survey results are tabulated in Table E2.3 and respondent locations are depicted in a map of the U.S. in Figure E2.1 (Gambatese and Tymvios, 2013). Table E2.3. Survey responses – Barrier types used by U.S. state DOTs (Gambatese and Tymvios, 2013) Is the barrier system used? Blasi Beam MBT -1® Armor Guard Barrier Guard Vulcan Barrier CRT S SRT S K- Rail Water Filled Yes 1 0 0 1 0 2 1 5 9 Uncertain 2 3 3 4 4 3 4 4 2 No 13 12 12 10 11 10 9 4 4 Total (# of responses) 16 15 15 15 15 15 14 13 15

146 Figure E2.1. State DOTs that responded to survey (Gambatese and Tymvios, 2013) When asked about the amount of time, equipment, and personnel needed for each activity, ODOT managers reported that the type of work they perform is “highly reactionary,” and that the amount of equipment and personnel needed differs depending on the level of repair or work needed (Gambatese and Tymvios, 2013). A mobile barrier takes up a lot of space and also provides less space for the employees to work. The trailer needs a housing/storage place with dimensions of at least 102 feet long by 8.33 feet wide, plus 5 feet as a buffer space to move around the mobile barrier (https://www.mobilebarriers.com/resources-mutcd-drawings-guidance.html). The costs of a mobile barrier are not inconsequential. If impacted by a vehicle, the Balsi Beam has high maintenance and repair costs. A rough estimate for the ownership costs of the trailer, according to MnDOT employees interviewed, is approximately $330,000, excluding taxes. However, one of the research findings related to the MBT-1® trailer was that the cost-benefit was found to be $1.9 million per year, per barrier (https://www.mobilebarriers.com/media/docs/Cost%20Benefit%20Analysis%20w%20FEMA- DHS%20Justification%20re%20Mobile%20Barriers%20MBT-1%20rev%20170605.pdf). Observed Technology Impacts and Effectiveness An ongoing project in California illustrates even greater potential savings on projects and benefits for the public as a result of the use of a mobile barrier (https://www.workzonebarriers.com/). Highly mobile barriers are saving an estimated 1-2 hours per night on setup/removal (a 10-20% savings in time and potential project duration). In one closed lane, they are using two barriers to work at different spots along that lane. On a three-year, $150-200 million project, that savings amounts to substantial reduction in project duration and cost. For the public, benefits are increased even further by shifting lanes around the work zone using movable concrete barrier. Used together, the highly mobile and movable barriers better maintain traffic flows and reduce overall project duration (https://www.workzonebarriers.com/). The following observations were recorded and documented as part of ODOT’s study of mobile barriers (Gambatese and Tymvios, 2013):

147 • The MBT-1® is seen as a guard barrier between the work zone area and flowing traffic which provides a higher level of comfort for the workers, but sometimes it is perceived as a false sense of security. This comfort and protection eliminate the need for a worker to act as a spotter for possible hazards that they might be exposed to from the passing vehicles. • While using barrels along with the mobile barrier, this type of system layout takes up extra space and makes it difficult for passing vehicles to pass by the work area. • In one of the use case scenarios, the mobile barrier was struck by a passing vehicle due to a narrowing of the passageway between the lane markers and guard rail. • In one instance the mobile barrier when was positioned along the lane line, the cab got side swiped by a passing vehicle due to a sudden shift from the wider open lane to a narrower lane resulting from the presence of the mobile barrier. • Noise from the adjacent traffic is significantly reduced while using the mobile barrier. Most of the workers remarked that they could carry on a conversation with a co-worker in a normal voice when standing behind the mobile barrier. Without the barrier, the workers have to speak louder in order to give instructions and coordinate their work. • The MBT-1® facilitates the installation of additional lighting and the work zone can be illuminated to a very comfortable level, reducing the need for additional lighting equipment. Eliminating the need for additional light equipment allows the work site to be less crowded. Placing the lights on the MBT-1® also facilitates providing light right at the work area that does not create disabling glare for the passing motorists. • The mobile barrier has a separate compartment that serves as a toolkit and eliminates the need of an additional vehicle. • The observed vehicle speeds through the work area were faster when the mobile barrier was present, and a positive impact on motorist behavior was also experienced (less distracted driving due to the inability to see the ongoing work and workers behind the tall mobile barrier). One MnDOT employee interviewed commented that a sense of complete protection is felt by workers on some projects. If the manufacturer adds additional safety components, the DOT will buy the mobile barrier trailer. In terms of productivity, the mobile barrier was found to limit productivity in different locations, especially in small spaces. The use is functional for a small area for long-term duration, and also is compatible with the bridge crew, as indicated by the ODOT employees interviewed. The workers did not feel comfortable reconfiguring the mobile barrier (changing the barrier from one side to the other side) during the same work day. The ODOT personnel interviewed indicated that several physical limitations of the barrier were encountered by the bridge crew due to the mobile barrier’s size and the process for reconfiguring the barrier. The experience of the ODOT bridge crew includes: o Movement of mobile barrier in the presence of live traffic was difficult. o A need for pre-planning is required in order to close a lane during the work zone duration. The truck had to be reconfigured to protect the side of the road which was exposed, and in some cases the trailer had to be relocated in order to do so.

148 Barriers to Use and Limitations to Effectiveness For the MBT-1®, space is needed to switch out the axle connections and reconfigure the barrier to the other side. For planning such an operation, according to MnDOT personnel interviewed, the crew can use the mobile barrier on one side of the work zone and finish that part of work first. Then, at the end of the day, the direction is switched from left to right or vice-versa, and then work is continued for other side in the work zone. In some cases, a mobile barrier is used in combination with barriers and/or cones for TTC. When using both the mobile barrier and cones/barrels, ODOT employees interviewed recommend providing extra space as the barrier extend may from the working lane into the adjacent through lane. The functionality of the MBT-1® barrier was demonstrated by its serving as a toolbox for the Illinois Tollway to maintain a steady traffic flow and provide protection to the workers (https://www.mobilebarriers.com/media/docs/Inside%20the%20Tollway%20- %20Illinois%20Tollway.pdf). The barrier provided more protection to the workers compared with other traffic control measures and provided space for work along the sides of the work zone while the traffic was open. The Tollway recently welcomed counterparts from the Indiana Toll Road to demonstrate the use of the work zone barrier to promote work zone safety and awareness. The Illinois Tollway’s two mobile barrier units provide flexible protection and can be deployed alongside a work zone, or in a rapid response scenario to adapt to changing conditions. Each unit comes fully equipped with features to ensure comprehensive on-site logistics, including power, lights, rear-facing barriers (i.e., TMAs), modular capabilities, and signage to direct the flow of traffic. The units are designed to provide 42-102 feet of work zone protection with minimal vehicle deflection and have been crash tested under industry standards (https://www.mobilebarriers.com/media/docs/Inside%20the%20Tollway%20- %20Illinois%20Tollway.pdf). The Washington State Department of Transportation (WSDOT) implemented an MBT-1® on one of their work sites on Interstate 5 in Washington (https://www.mobilebarriers.com/media/docs/WA%20WSDOT%20Mobile%20Barrier%20Hit% 20-%20Helping%20Save%20Lives.pdf). During the course of the work, the mobile barrier helped successfully prevent the vehicle intrusion by an out-of-control car. The vehicle crashed into the mobile barrier and not the crew. The MBT-1® served its purpose and no worker was harmed.

149 3. ATMA Technology Description and Functions TMA, also referred to as an impact attenuator and crash attenuator, is a device mounted to a truck that is designed to reduce the damage resulting from an errant motor vehicle collision into the truck. TMAs are commonly used for protection of workers during many different types of roadway construction operations. An ATMA is an autonomous truck with a TMA. As an autonomous vehicle, the ATMA uses advance object detection and communications to allow it to follow a lead vehicle autonomously, i.e., without a driver. This capability removes a worker from being exposed to potential crashes while still providing protection to the lead vehicle. Kratos Defense, along with Royal Truck and Equipment pioneered the field of “Highly Automated Work Zone” vehicles, by deploying the world’s first ATMA, also known as an AIPV (Kratos Defense, n.d.). The unmanned ATMA/AIPV concept was leveraged from systems Kratos Defense developed for the U.S. Military to reduce warfighter support of dangerous missions by converting human-driven convoy vehicles into unmanned systems (Kratos Defense, n.d.). Some state DOTs, like Caltrans and CDOT, are utilizing ATMAs in their construction and maintenance operations. In an interview with Caltrans employees, the interviewees stressed the recent developments in the technology, and expressed that the ATMA is still being developed. Manufacturers are making adjustments to the systems used by Caltrans, with upgrades according to issues raised by Caltrans. The ATMA technology used by Caltrans and other similar systems have a variety of capabilities. Kratos Defense, for example, has automated fleet vehicles using a multi-platform applique kit (M- PAK) to enable the self-drive feature in multi-vehicle leader/follower operations with a human- driven highway maintenance vehicle (i.e., line striping or road sweeper vehicle). In the leader/follower configuration system, the maintenance (lead) vehicle transmits navigation data via encrypted vehicle-to-vehicle (V2V) communications to the ATMA (follower). The trailing vehicle uses the data to follow behind the lead vehicle. The following vehicle is completely unmanned and follows along the route taken by the lead vehicle. The ATMA system features component redundancy, an active safety system, high accuracy GPS/GPS-Denied navigation, encrypted V2V communications, front and side view obstacle detection, and a robust user interface which provides system feedback, situational awareness, multi-camera view, and operator control (Kratos, n.d.) Lane closures on multi-lane roads requires drivers to transition safely to an open lane before passing the work zone. To reduce worker and driver injury risk, TMAs are often used before the transition section of the work zone to prevent vehicle work zone intrusions and reduce the severity of collisions. To maximize the efficiency and effectiveness of TMA use, consideration should be given to how and when TMAs are deployed as well as the best supporting measures (Blackman et al., 2020). TMAs are frequently used along the work zone to provide positive protection for working crew members on high-speed roads, such as highways and freeways, and located on the roadsides. TMAs are present to serve as a barrier between the buffer area/transition zone and the workers, and can also reduce the severity of injuries to motorists and passenger vehicles that fail to respond

150 to traffic controls and associated guidance by absorbing the impact of collisions (Blackman et al., 2020). In a study of how shadow vehicles such as TMAs affect driver behavior (Blackman et al., 2020), the tail vehicles were equipped with variable message signs (VMSs) depicting arrows and lane closure symbols combined with static “Reduce Speed” and “60” speed limit signs. The TMA vehicle was equipped with top-mounted arrow lights, a VMS depicting a “roadworker” symbol and speed limit, and directional red/white retroreflective rear markings. Both the TMA and tail vehicles were equipped with amber rotating beacons. The above devices attached to the ATMA informed the road user of a work zone coming up ahead (Blackman et al., 2020). The design of ATMAs is such that it operates on its own based on the features and functionality of the technology and so that there is no need for a human behind the wheel (Kratos, n.d.). The study incorporated three traffic management plans (TMPs) differing by the number of tail vehicles deployed and the presence/absence of a police vehicle with flashing lights stationed in the work area (Blackman et al., 2020). Figure E3.1 shows the TMPs included in the study. (Note: The study was conducted at a location where driving is on the left side of a roadway, as depicted in Figure E3.1.) The responses from the drivers were captured through a camera. The TMP configuration for the three sites was as follows: TMP1 had two tail vehicles (baseline), TMP2 had three tail vehicles, and TMP3 had two tail vehicles plus a police vehicle. In addition, three work sites were included in the study. Sites 1 and 3 had two lanes open to traffic before the lane closure, compared with three open lanes in Site 2. The speed reduction sequence was consistent across all three sites and TMPs (Blackman et al., 2020).

151 Figure E3.1. TMPs 1–3 and camera placement (drive on left) (Blackman et al., 2020) The testing was done for a period of 1 hour for each traffic management plan, on three consecutive weeknights from July to August, 2018. Progressing through each site, drivers would pass through an advance warning area consisting of, in order of occurrence: (1) tail vehicle 3 with arrow board and “60 Ahead” static sign (TMP2 only); (2) tail vehicle 2 with “Reduce Speed” and “60 Ahead” signs; and (3) tail vehicle 1 with VMS showing lane closure symbol and “Reduce Speed” and “60” signs. For TMP3, a police car with red and blue lights flashing was stationed in the closed lane 40m (130 ft) downstream of the TMA (buffer area). While a nominal spacing of 300 m between traffic management vehicles was preferred for this study, some variation was required as isolated roadside characteristics prevented consistency across sites. Spacing between tail vehicles and the TMA, and between tail vehicles themselves, varied by up to 100 m (330 ft). This spacing resulted

152 in overall site lengths of between 950 m and 1,100 m (0.59–0.68 mi) from tail vehicle 3 (where present in TMP2) to the TMA (Blackman et al., 2020). Due to the short-term work zones used in the study, the data collection needed to be rapid and accurate (Blackman et al., 2020). To meet the above conditions, rapid installation and removal of equipment is required. For safety reasons, entrance to the live traffic lane was closed off and this condition did not allow the research team enough time to install and place the equipment. Customized cameras were needed to record traffic movements, with images later processed to extract the vehicle speed, lane position and point of capture. Postprocessing accuracy of speed measurement averaged +/- 2 km/h using specialized software. Figure E3.2 shows the use of camera tripod placed at a location beyond the work zone area (Blackman et al., 2020). Figure E3.2. Camera tripod placed beyond work zone area (Blackman et al., 2020) In a recent research study (Kohls, 2020), the results suggest that an ATMA provides the primary benefit of enhanced operational safety through not having a driver present in the TMA truck, and the ATMA system is designed to maintain the buffer distance to the lead vehicle at a greater accuracy than a human driver. The leader vehicle system relays the signals about its position, speed, and route to the ATMA vehicle through sequential vehicle-to-vehicle (V2V) “e-Crumb” electronic crumb messages. The ATMA uses the self-drive feature based on the electronic crumb messages and follows the leader vehicle path at a fixed distance (Kohls, 2020). Technology Adoption Work utilizing ATMAs is often performed at night. Nighttime work zone activities have been the focus of concern due to work zone intrusions, and research and development related to nighttime work zones has increased. Highway construction and maintenance is often performed throughout the night to minimize traffic delays during high-volume times during the day. Factors contributing to nighttime work zone facilities are listed in Table E3.1. The developed ATMA helps to mitigate

153 all of these factors, and can be used on roads to reduce the number of fatalities (Hallowell et al., 2010). Table E3.1. Factors contributing to nighttime work zone fatalities (Hallowell et al., 2010) Factors Contributing to Nighttime Work Zone Fatalities % of fatalities attributed Fatigue or impairment of vehicle operators 64% Poor lighting conditions 43% Workers not wearing safety garments 14% Unfavorable weather 8% Poor performance of safety garments 7% Other 32% According to Caltrans employees interviewed, Caltrans plans to deploy ATMAs instead of using driver-operated TMAs. California’s State Law prohibits the use of AVs as the weight surpasses the limitation of 10,000 pounds. Caltrans has been communicating with the California Department of Motor Vehicles to find an exemption to use ATMAs during the work zone operations. Those Caltrans employees interviewed stated that closed course testing of an ATMA has been conducted by Caltrans and issues and suggestions noted by Caltrans are being resolved by the ATMA manufacturer. A concern related to an ATMA swerving in the lane during operation is being taken care of by the ATMA manufacturer through internal testing, and Caltrans expects an update by the end of September 2021. A paint striping operation under the project titled “RoadX – Accelerating Technology” was carried out for roads with annual average daily traffic of less than 5,000 vehicles per day on long flat, rural roadways. The primary benefits observed using energy absorbing TMAs were to prevent rear-end crashes, and removal of drivers from harm’s way, including potential death or lifelong injury The presence of remote operation of the TMA vehicle ensures that the purpose of the crash stays true as human drivers usually tend to drive away from nearby crashes and the TMA vehicle promotes a layer of protection for the leader vehicle. The major concern was that the ATMA systems were operating on a flat roadway which had a more responsive gap control, and the systems are most suitable for mainline maintenance operations in the work zone, such as sweeping and lane striping operations (Kohls, 2020). Pre-planning and Implementation Plan The ATMA vehicle should be able to withstand the impact of vehicles on high-speed roadways which have speed limits ranging from 65 mph to 75 mph, such as a state highway or interstate freeway. The impact of a vehicle collision with the ATMA vehicle is much more dramatic on roads having speed limits up to 75 mph as compared to auxiliary and secondary roads having a speed limit of 35 mph. The Caltrans employees interviewed stated that the ATMA vendor provides detailed extensive training and system checks for two days where the system components are tested and validated. A training manual is provided and issues can be raised regarding safety and operation. The training consists of in-cab training. Two specific features are of focus in the training: E-Stop and A-Stop.

154 E-Stop, or emergency stop, is a button that the lead vehicle driver can press when an obstacle is encountered that could not be crossed over or during emergency events When the E-Stop button is pressed, the system simultaneously sends a signal to the following ATMA vehicle to stop. The A-Stop feature is for “automated stop” where the vehicle system detects obstacles in the vehicle’s path and, when the sensors pick up an obstacle that is very large in which the lead vehicle cannot pass over or by, the lead vehicle communicates with the trailing ATMA vehicle to stop. According to Caltrans employees interviewed, the drawback of the E-Stop feature is that the system has to re- boot manually while the ATMA vehicles remain stationary until the operations system was functional. In 2020, there was a major update to the ATMA software systems and the hardware was updated with new sensors. Caltrans employees interviewed said that new tests will be conducted to verify that the identified issues have be fixed. For example, with respect to the issue associated with loss of connection when passing under a bridge, the issue was deemed resolved when the ATMA system passed in 12 out of 15 tests. These tests indicated the system is functional. Following the new upgrade, the underpass test can be avoided or an additional five tests could be run as the ATMA system has already been tested successfully during the previous round of tests. Maintenance of the operating system will be reduced as ATMA vendors upgrade their models. Caltrans has successfully tested a third version, and is waiting to receive the fourth version. Conversely, maintenance of the hardware will be an issue and, according to the Caltrans employees interviewed, could be worked out as an agreement with the manufacturer or a partner company. Other rigorous tests have been conducted to evaluate the effectiveness of the ATMA in the U.S. and England, specifically pertaining to paint striping in slow-moving operations. The first test was performed on a closed course performance airstrip of 4,000 ft in length, and the next test occurred on a public, open roadway with a human driver in the ATMA for safety precautions. Following the tests, significant upgrades to the software and hardware were made. In between these tests, the issues and updates were documented to form a manual for the users. Along with tests, several DOT organizations followed closely with the tests and collaborated with the vendors to point out and resolve issues. A collaborative research study was conducted to improve the safety, efficiency, and quality of work in the field of autonomous vehicle technologies. The following scope of research work was included in the research and development efforts: improvements in existing ATMA/AIPV platforms, expansion of the use of ATMA/AIPV platforms beyond striping, refining policy and operational procedures for AVs through collaborative government agencies efforts, and investigating additional applications for AVs in maintenance operations (Kohls, 2020; Kratos Defense, n.d.). Pilot testing of the ATMA occurred in 2019 at locations selected based on roadway characteristics that present challenging topographical and geometric conditions. For safety concerns, a driver was present in the TMA vehicle at all times. A detailed list of the tests conducted and the results are presented in Table E3.2. Data of the path of the vehicles were extracted and layered on Google Earth maps. Other data were presented in the form of scattered charts. The green cells shown in Table E3.2 represent those tests in which the results of the tests were successful, while the red cells indicate the results of the tests that had some failures or other issues (Kohls, 2020).

155 Table E3.2. ATMA tests conducted and results (Kohls, 2020) ATMA Testing Results Test Scenario # Test Category Description Location Results 1 Safety Automatic Stop (A-Stop) – Leader Vehicle Internal Button I-840 2 Safety Emergency Stop (E-Stop) – Leader Vehicle Internal Button I-840 3 Safety Emergency Stop (E-Stop) – ATMA External Button I-840 4 Safety Emergency Stop (E-Stop) – ATMA Internal Button I-840 5 Following Accuracy Following Accuracy on Straight Line I-840 CTE GAP 6 Following Accuracy Following Accuracy on Slalom Course I-840 CTE GAP 7 Following Accuracy Following Accuracy on Lane Change I-840 CTE GAP 8 Following Accuracy Adjusting Following Distance I-840 9 Typical Applications Trash Pick Up I-840 10 Typical Applications Herbicide Application I-840 11 Typical Applications Pothole Patching I-840 Detection GAP 12 Detection Obstacle Detection – FRONT I-840 13 Detection Vehicle Intrusion I-840 14 Detection Sensitivity to Passing Vehicles I-840 15 Detection Object Recognition TDSTC / TIM 16 Detection Headlights TDSTC / TIM 17 Detection Cone Detection TDSTC / TIM 18 Miscellaneous Speed Test I-840 19 Miscellaneous Braking – Leader Vehicle I-840 20 Miscellaneous Bump Test TDSTC / TIM 21 Miscellaneous Leader Reverse TDSTC / TIM 22 Miscellaneous Turning at I-840 I-840 23 Miscellaneous Tight Turn Radius TDSTC / TIM 24 Communication Loss of Communication TDSTC / TIM Observed Technology Impacts and Effectiveness Users of the ATMA system indicate that there is better lateral control accuracy and the ATMA exceeds expectations with respect to its designed uses. During one of the ATMA tests on a closed section off the highway, Caltrans employees interviewed stated that an ATMA vehicle lost the connection to the leader vehicle when passing underneath a bridge. The interrupted connection was due to a loss of connection with the GPS, and the inertial navigation was activated. However, the ATMA swerved pretty dramatically as it got reconnected with the lead vehicle via GPS. In such instances, the ATMA system uses gyros and/or wheel encoders in combination and the system integrates a forward projection as a solution. The forward projection is precise for a short distance and time, but will tend to drift off in the long run. The ATMA vendor company has taken into account the curvature of the road not being detected by the ATMA. According to Caltrans employees interviewed, the identified issue has been resolved and the ATMA has been updated with a new radar-LiDAR hardware component in the front of the vehicle which takes into account obstacle detection with a FOV of 180 degrees. The ATMA control system used for positioning, navigation, and communication requires re- booting in various circumstances. In some cases, the wait time for re-booting the system can be lengthy. However, with recent system upgrades, the wait time is significantly reduced from five minutes to 15 to 20 seconds. Similarly, an issue with alignment during the system re-boot is being

156 fixed with upcoming system updates. The cost-benefit trade off can be seen as a concern, but the features and application can be justified for the cost. Caltrans addressed a concern that if there is an incident in which the lead vehicle is involved in a crash, the workers and drivers will be out of work for a period of time. Worker union issues are also a factor that should be considered. A driver has to be employed specifically to take care of the ATMA while it is operational in the work zone boundaries and to drive the ATMA to and from the work zone operation site. California State laws do not allow the use of “AVs,” however this regulation is not stressed right now as the ATMA is still in its research and development stage. Those Caltrans employees interviewed indicated that the base purchase cost of the ATMA was projected to be approximately around $330,000, which increased to $410,000 with the upgrades. Several connection issues arose between the lead vehicle and the ATMA vehicle such as a loss of GPS during a test on a flat rural roadway (Kohls, 2020). Another setback experienced was a connection issue when the ATMA went under an underpass and the ATMA vehicle swerved dramatically. In another instance, various tests were conducted to evaluate the automated stopping function, the emergency stop feature, lane changing capability, and accuracy in terms of speed and distance. A test also involved the case where a vehicle intrudes between the lead vehicle and following ATMA vehicle in urban and rural environmental settings. The results of the test were not available (Kohls, 2020). Recommendations for Use Use of the ATMA is recommended by Caltrans employees interviewed for paint striping where the ATMA vehicle follows the paint truck (lead vehicle) at a projected speed of 10 to 20 mph. However, moving forward with using the ATMA in this way at this time requires resolving operational issues through system updates or installing new hardware components. Apart from paint striping, maintenance personnel have indicated that the ATMA also shows excellent potential application for pot hole filling operations. Though many tests have been conducted, the functional use of an ATMA was impactful due to the features provided (Kohls, 2020). At this point unresolved issues are present that need to be taken care of before actual use on a public roadway. On the bright side, the tests revealed that an ATMA is useful for long-term continuous movement for retracing or installing pavement markings and for roadway sweeping (Kohls, 2020).

157 4. SMART WORK ZONE (QUEUE WARNING SYTEM, DMS, AND SPEED ENFORCEMENT) Technology Description and Functions A smart work zone, also known as an intelligent work zone, is a site-specific configuration of traffic control technology installed within a roadway work zone to improve construction worker safety, give “real-time” travel information to the road users, and efficiently route vehicles through a work zone. Examples of smart work zones are QWS, truck warning systems, and DMS. QWSs give warnings to the vehicle drivers about oncoming traffic queues by using PCMSs. QWSs provide warnings to the drivers at the upstream location of work zone. Another QWS functionality is that it displays messages to the vehicle drivers to slow down due to the traffic ahead or take a detour to save time before the starting point of the traffic queue. This technology is used in traffic environments where backend/rear incidents of the vehicles occur in high frequency around work zones. DMSs have been employed in highway work zones as an innovative TTC device in the United States for many years. Their development as seen through the past years has proven to be effective at decreasing vehicle mean speed before the work zone by implementing numerous sign changes such as a moving animation displayed instead of a text-based message, radar attached to the message sign that allows for notifying the drivers of their speed, and changing the rate of flashes per minute to socially influence the vehicle drivers. Figure E4.1 shows a DMS along a roadway at the entrance to a work zone. Figure E4.1: DMS in use around highway work zone (https://www.fhwa.dot.gov/publications/publicroads/18summer/01.cfm) Technology Applications, Set Up, and Use

158 QWS contain sensors, a portable variable message sign (PVMS) board, a communication system and operating system. The PVMS boards are spaced out in equal intervals starting from a point upstream and then through the work zone. When slow or stopped traffic is detected by the sensors, a warning message is triggered on the PVMS board (Waldman, 2020b). The CDOT Region 1 Traffic and Safety division worked in coordination on the I-25 Gap Project to deploy smart work zone (SWZ) technologies that included QWS, truck entry systems, and portable variable speed limit (PVSL) systems. The length of the construction zone was approximately 20 miles and stretched from Monument to Castle Rock with construction activity divided into three separate sections that occur simultaneously. The project is expected to be completed in 2022. Due to the construction timing as well as frequent instances of traffic flow being interrupted by construction vehicles and equipment, the work resulted in long queues and delays along with increases in the number of vehicle crashes around work zones. SWZ technologies are deployed in practice, with mainly QWSs used due to the substantial benefits described in the documentation of the device vendors. The speed sensors used are either “Doppler sensors” or “Microwave Radar Detection Sensors” that are connected to a PVMS placed in the transition phase of the work zone. Messages are displayed to vehicles containing information on the vehicles ahead, as follows: • To the slower traffic: “Slow down ahead please watch,” and “drive slowly” • To the stopped traffic: “Stopped vehicle ahead,” and “stopped traffic ahead” QWS are easily incorporated into the project needs and specifications. Furthermore, analysis is required to determine approximate length of queue so that the appropriate number and locations of traffic sensors and PVMSs can be identified through the project plans prior to construction. Example Applications An example setup of a QWS is shown in Figure E4.2 where the Doppler sensors and MVDRs are present along the curved length of the road that enables the operating system to recognize the traffic flow (Waldman, 2020b).

159 Figure E4.2. Location of SWZ devices (Waldman, 2020b) The QWS are set up around the curved sections of roads right before the work zone starts on the project. The technology is used on highway and interstate roadway projects where the topographical features contain mountainous regions having curved roads and different elevations along the road length. The connected devices provided a source of data collection and public information throughout the project extent. Figure E4.3 shows another QWS setup for the CDOT project on I25 (Waldman, 2020b). The QWS setup was to provide automated warning messages to travelers when slow or stopped traffic is expected at the upstream side of the work zone (PCMS 4 location) based on the real-time speed and travel time information collected by the Bluetooth and Doppler sensors.

160 Figure E4.3. Queue warning system layout on I-25 (Waldman, 2020b) CDOT developed “rules” to guide travelers through the dynamic messages displayed on board. Table E4.1 shows the rules, which are specific to the southbound 1-25 Gap Queue Warning System setup. Table E4.1. Rules for QWS setup (CDOT) No. Speed Limit Traffic Flow Condition Travel Time Status of Message Board 1 Greater than 45 mph Free flow of traffic is observed <15 minutes Inactive 2 45 mph > Speed > 20 mph Slow traffic >15 minutes Caution slow traffic; prepare to stop 3 Speed dropped below 20 mph Stopped traffic message >20 minutes Stopped traffic ahead; prepare to stop 4 Not Applicable Not Applicable Displayed continuously on PCMS 4 Tomah Road/Larkspur 9-miles/11-miles XX minutes/XX minutes Pre-planning and Implementation Plan For CDOT, the operations plans are developed in concurrence with the SWZ design details. All SWZ design details, project specifications, and the operations plan are provided to the CDOT Project Manager prior to 90% design stage in order to evaluate the Final Office Review (FOR) plans, specifications, and estimate package.

161 Along with a discussion of integration and testing aspects of the SWZ, the introduction of the SWZ operation plan is seen at the Final Office Review meeting. This collaboration enables the designers, construction members, DOT agencies, and other stakeholders to discuss the roles and responsibilities for the construction phase. This meeting enables the stakeholders to refine the plans and details of the SWZ operations while time is still available. An operation plan is provided in the form of a SWZ logic diagram, which is drafted to identify the equipment needed for the SWZ system. The details furnished after the draft plan is written are as follows: • Brief description of SWZ system and project name • Description of devices being used • Location and direction of each device • Message strategy for the PVMSs • Traffic conditions / thresholds for altering messages The SWZ system integration, testing procedure, and frequency of the tests for the project development are carried out by the contractor responsible for the CDOT project. Accuracy is guaranteed if optimal setup conditions are met. This process is seen as labor-intensive and can be achieved through training for the contractors, which is important. As expressed by CDOT employees, the initial cost and maintenance cost of the QWS are very high. If possible, the vendor may be contacted for making field adjustments and this process can be useful to develop a training report or guide. The following measures were needed on a weekly basis to ensure the QWS was operating as it was specified: Visual inspection in the field: The placement of sensors and message boards should be reviewed. Sensors should be placed at the specified locations and the message boards should be visible and in the line of sight of the travelers. Data Verification: • Data collected by the devices should be downloaded and reviewed for inconsistent data measures and if the devices are operational. • Validation and data export should be done through a common software program, such as Microsoft Excel, by the vendors, and the Government agencies. • Field Adjustments: If necessary, the vendor must be contacted for field adjustments to the devices. • Verification: Along with visual inspections, review of data, and field adjustments, verification may be accompanied to ensure the entire process is completed as per the standard. Data validation was monitored monthly to ensure that the sensors and automated messages were operational. The QWS data was downloaded using 1-minute intervals to collect the data with high granularity, and was compared with the available data collected by the sensors used by CDOT.

162 The Bluetooth travel sensor time data was compared with the CDOT COGNOS database and included Device 025N174, Device 025N175, and Device 025N177, which were located at Tomah Road intersection, 1.8 mile north of Tomah Road and 3.8 miles south of Plum Creek Parkway. One of the specifications included was not to repeat static messages, such as “Caution,” on the DMS. The proper abbreviation of commonly used roadway terms, for example, as in direction: Right was shortened to “RT” and left as “LT,” allowed consistency in reading messages by the road users. Another issue experienced was that it was costly when the optimal number of DMSs were used. Observed Technology Impacts and Effectiveness The field observations and the QWS data indicated consistency with available data and the Bluetooth travel time captured by the devices. This test confirms that the QWS performs as it was reported through data by the vendor. There was an abrupt speed reduction when the QWS informed the vehicle drivers through the sign “Slow traffic ahead” and “Stopped traffic ahead.” The results of the average speed measure of effectiveness (MOE) and abrupt speed reduction MOE indicate positive impact of the QWS on the traffic flow. The QWS system was able to reduce abrupt speed reduction and increase the travel speeds occurring through the I-25 project, resulting in smooth traffic conditions for the public roadway users. The reliability of the operation of the QWS device is seen as an issue during early monitoring. The data validation process enabled an opportunity to work successfully with the vendor on pertinent issues within the QWS components. After several months of efficacious collaboration with the smart merchant, data reliability improved significantly. Regular visual inspections and review of detection data along with pay reduction penalty enforced proved to be effective to improve the reliability of the devices. Figure E4.4 represents the period of reliable data from the sensors, i.e., from the period starting in mid- December 2019. Sensor 2 and Sensor 1 showed no speed detected more than 60%. This result remained true until December 2020, where the device reliability shot up to 90%. Figure E4.4. QWS data gap reliability profile (CDOT)

163 The effectiveness of the QWS was evaluated using two MOEs. Both MOEs consist of 1-month period with the QWS and 1-month period with the system. This process was initiated without the message signs being visible to the public. The two MOEs included were: 1. Average speed: This comparison is with the average speed during the warning message activation consisting of spot measurements of average speed at each sensor location during QWS activation time periods. The average speeds are measured during message activations for 1-month period for both visible and non-visible when the vehicles approach the restrained queue. 2. Abrupt speed reduction: A comparison of abrupt speed drop frequencies within 1-minute periods during QWS activation periods when the travelers approach the measured queue. The measure was analyzed by counting the number of 10+ and 15+ speed reductions while the messages were visible for 1 month and the message was not visible for the following 1-month period. Sensors 2 and 4 did not capture the data when the sign was not visible to the vehicle drivers. On the other hand, the data from sensors 1 and 3 depict less unexpected speed reductions while the message was visible. The overall results combined from both MOEs display positive impact by the QWS on the traffic flow by increasing traffic flow and decreasing the unforeseen speed changes. Barriers to Use and Limitations to Effectiveness QWS system updates were required every two months, and the vehicles were susceptible to rear- end crashes when the QWS was updating. Sometimes, drivers did not slow down adjacent curves when they saw the PCMS; this driving behavior would ultimately cause a disruption in the traffic flow. In some cases, the QWS could not be used in bridge work zone operations as the space is limited along the length of the corridors and physical limitations. Reconfiguration of the device was necessary as workers keep moving devices on their way. Practitioners also noted that they had a hard time facing the sign towards the traffic. The system works only if a high level of maintenance is provided. Accuracy is guaranteed, but only in optimal physical conditions exist. The communications systems had some network issues such as signals not being received from the sensor to the VSL. Due to movement of the traffic alignment ramp, the portable system had to be moved a lot, thereby resulting in significant manual labor. Recommendations for Use Based on interviews with CDOT employees, QWS were noted to be useful and applicable in regions where curved sections and different elevations of the roads are found. DMS In addition to their use with a QWS, DMSs can be used in isolation and interviews were conducted with ALDOT employees to obtain user insights in this regard. The results of the interviews are provided below on the basis of the case study interview and previously published studies based on data collected in Missouri (Shaw et al., 2015; Edara et al., 2011).

164 It was observed on a project in Tuscaloosa, AL that the work crew liked the DMS system. The public was aware of the upcoming road conditions and helped to avoid high-speed crashes and prevent traffic congestion. This project was considered for using the DMS as it had detour routes and was a federally funded project. The DMS rerouted the vehicle flow around the work zone. The vehicles rerouted and drove around the work zone which resulted in success. For testing done in Stockton, MO, the lane closure alone without a trailer, reduced the average traffic speed by approximately 5 mph to 5.5 mph. The use of police vehicles with their flashing lights turned on further produced a speed reduction of 3 to 7 mph in the work zone and beyond. Use of a highway patrol car in addition to a speed trailer reduced speeds by approximately 5 to 9 mph. Some of the other speed reductions may be a result of other devices present in the DMS system. A set of questions through a survey were used to examine the effectiveness of DMSs in diverting traffic to a detour route during a full motorway shutdown. The I-57 bridge over the Mississippi River was closed for three days to be repaired. Because of the bridge shutdown, traffic on I-57 between Missouri and Illinois had to divert. Motorist surveys were undertaken in the impacted area to determine whether or not motorists were aware of the bridge closure and detour, as well as how much they depended on DMSs for traveler information. Overall, motorists stated that they were satisfied with the traveler information supplied by the DOT via the DMSs, that they trusted the accuracy and sufficiency of the detour information provided on DMS, and that they followed the advice offered by the DOT to implement the DMSs during the bridge closure project. Truck drivers were happier with the entire information dissemination procedure, providing a higher average rating for each question than private car drivers. Among the notable comments were their high ratings for the level of faith in the advised detours, use of DMS suggestions, and sufficiency of DMS information (Edara et al. 2011). Figure E4.5 shows the road pathway before and after the road closure.

165 Figure E4.5. Road pathway before (left) and after (right) the road closure (Edara et al. 2011) In a study by Shaw et al. (2015), two DMSs that showed messages on the I-55 highway construction project in Missouri successfully warned drivers of the impending work zone. The average speed of cars measured before and after the DMS were used to determine whether or not drivers changed their speeds in response to the displayed message. Speeds fell when the DMSs indicated a positive safety effect message sign at both sites. Speed reductions of 3.64 mph and 1.25 mph were found at the first and second sites, respectively, and were deemed statistically significant. These findings suggest that the DMSs had a favorable influence on driver speeds upstream of the construction zones on rural, non-congested, four-lane interstates.

166 5. IAS Technology Description and Functions IASs with or without networked sensors typically use various types of sensors attached to channelizing devices that can detect intrusions into a work zone. Some systems have alarms attached to the cone or barrel along with the sensor, while other systems use radio waves to facilitate two-way communication between sensors and the alarm unit placed elsewhere. Such systems consist of multiple technologies coupled together that serve as a multifunctional device capable to inform workers prior to or during a work zone intrusion incident. Brief overviews of several IAS technologies are provided below (Sanni, 2019): • Microwave and pneumatic technology systems are two technologies that are integrated into a single system in the WAS device. The system utilizes pneumatic tubes placed perpendicular or along the work zone area boundary. The pneumatic tube is connected to a transmitter which activates the alert mechanisms. Microwave systems consist of a transmitter, receiver, and a siren connected to other alert devices within a specified range. The alert devices are activated through the microwave signals which are sent by the transmitter when the base unit is triggered (the base unit is activated when the vehicle passes over the pneumatic tube). The microwave technology-based alert devices are usually mounted on traffic control devices and/or wearable devices worn by the workers. A typical application is seen in the WAS where the strobe lights and audible alert mechanism are activated when the vehicle passes over the pneumatic tube. • Kinematic energy-based technology is powered by kinematic systems and are activated when the device is struck or turned over by the vehicle. These devices are attached to a traffic control device such as a cone or barrel. The SonoBlaster is an impact-activated work zone intrusion device which, when the cone/barrel that it is attached to is struck by a vehicle, sounds an audible alarm. • Radio wave signal-based technology uses radio waves to communicate between sensors and alarm units. An example is the Intellicone, which uses the sensors to detect an intrusion and communicates with the alert devices. • Radar-based technology, such as the AWARE system, consists of devices which are electronically powered and contain a radar scanner, high-precision differential GPS, accelerometers, gyroscopes, and magnetometers that are used for position and orientation sensing of the vehicles. The AWARE system tracks the vehicle’s speed and location, and determines the likely path of the vehicle to assess if there is going to be a work zone intrusion. If so, the system activates warning lights and an audible alarm to warn workers and motorists in the work zone vicinity. Table E5.1 lists the various systems in this category along with their primary technology components and output warnings produced. Table E5.1. Summary of IAS

167 Intrusion Alert System Type of Sensor Technology Used Audio Alert Visual Alert Vibrational Alert Traffic Guard WAS Microwave and pneumatic tube-based Present Present Present SonoBlaster Kinematic energy Present Not present Not present Intellicone Radio wave signal Present Present Not present AWARE* Radar Present Present Present *The technology is still in its final development stages. Each of the technologies listed in Table E5.11 are described in more detail below. Traffic Guard WAS The WAS is an auditory and visual alarm which is wirelessly triggered when a vehicle passes over the pneumatic tube (https://www.trafficsafetywarehouse.com/). When triggered, the system activates the strobe lights, audible alarm, and a vibrational alert message to the workers. The different components of the WAS are: a PAC with pulsing sound blast and flashing light, a portable trip hose (houses the pneumatic tube) with a pressure sensor and a wireless transmitter, and personal safety devices (PSDs) with audible and vibrating alarms. The WAS features a 12 feet long trip hose with sensors, rechargeable alarm/flashing light, and available heavy-duty carrying case. The cost of the latest WAS is $495 per unit (Traffic Worker Alert System, 2021). WAS installation is done manually by the operator by laying out a pneumatic hose transverse to the flow of traffic and the steps to deploy are as follows. First the trip hose is deployed across the lane and the hose pressure sensor box is powered up by pressing a button. Second, the PAC is attached to a piece of equipment or infrastructure inside the work zone. Third, the workers turn on their PSDs and verify the green LED is visible. Lastly, the pneumatic hose is stepped on to trigger the alarm and test the system for its operability (Traffic Worker Alert System, 2021). The WAS operates or is activated as a vehicle passes over the trip hose when pressurized. The pressure sensor sends a signal wirelessly to the PAC and PSDs ranging up to 1,000 feet away. The PAC triggers the audible alarm and flashing light, alerting those nearby in the work zone at an audio level of 68 decibels (Traffic Worker Alert System, 2021). Employee exposure when laying out the tubes on the roadway was seen as a drawback. In addition, the limited length of pneumatic tube is an issue for long work areas, and vendor must be contacted to get the pneumatic tube of a specific length for use in long roadway closures. Another drawback was that workers needed to be in close vicinity to the WAS components in order to be alerted of the vehicle intrusion and gain reaction time to protect themselves from a vehicle intrusion (Mishra et al., 2021). Gambatese et al. (2017) noted that the WAS technology’s strengths are “ease of use” and “effectiveness of triggering mechanism.” The cost and effectiveness of the device’s alarm, on the other hand, were cited as disadvantages of implementing the WAS technology. The WAS is distinguished by the presence of an audible and vibratory (haptic) alarm generated by the PSD that personnel can carry in their pockets. Wrapping the device around one’s arm or putting it in one’s pocket will cause the vibration to be felt. The WAS alarm speaker location is asymmetrical, with

168 one speaker in the corner. The warning sound is 110 decibels at 0 feet and gradually decreases to around 85 dB at 50 feet. Alarm decibel levels do not fluctuate significantly from around 85 decibels at 50 feet to approximately 65 decibels at 300 feet. The radio wave transmission rate between the sensor and PSA is effective up to 100 percent at 400 feet and 0 percent at 500 feet. Researchers have found that the worker’s maximum median reaction time was roughly 1.22 seconds in response to an alarm with a mean duration of 4.7 seconds when the vehicle contacted the sensors at 30 mph (Mishra et al. 2021). Although the WAS technology may be valuable, it has been suggested that it be used on small scale operations such as city streets or a project with slow traffic rather than a highway project (Gambatese et al., 2017). Workers are alerted by the WAS flashing light and alarm, allowing them to move quickly out of the way of an approaching vehicle. The larger the distance between the pneumatic trip hose and the work area, the greater the pace of traffic (Mishra et al., 2021). A DOT employee interviewed noted that the best use case suggested for the WAS, along with Intellicone and SonoBlaster (described below), is in a ramp closure where the device is placed between barricades and there is low exposure to the worker. SonoBlaster Sonoblaster is a system that emits an audible alert sound which is activated when the cone or barrel to which the mechanism is attached is impacted/struck by a vehicle. The SonoBlaster consists of a CO2 cartridge and an alarm unit. When the cone/barrel is struck, the CO2 escapes from the cartridge and emits an air horn sound. This device can be mounted on traffic cones, drums, delineators, frames, and other type of barricades. The setup is to be done by a worker and the steps of installation are as follows: First, the mounting bracket should be installed at the base of the cone. Second, the SonoBlaster is cocked using a keychain tool. Third, the unit is placed in the work zone in “safe” mode. Lastly, the control knob is rotated from “safe” to “ready” mode, and the unit is active and ready to use. The SonoBlaster is activated when there is impact-tilt contact by the vehicle, and emits an audible alarm sound in the work zone at an audio level of 125 decibels for 15 seconds. The SonoBlaster CO2 cartridge is deemed as one-time-use only (Traffic Worker Alert System, 2021). Use of SonoBlaster is suggested in work zones around low-speed roads (Gambatese et al., 2017). The SonoBlaster has been used during daytime and nighttime projects. The SonoBlaster is relatively cheap and costs $89.95, accessories included (SonoBlaster® Work Zone Intrusion Alarm and Accessories, 2021). Even though the SonoBlaster is not very expensive, there were some issues experienced. Since the cones with the SonoBlaster units attached cannot be stored like regular cones, the setup and removal take more time than anticipated. Some SonoBlasters sound the alarm during setup due to poor supervision and the arming of the unit being difficult (Gambatese et al., 2017). The SonoBlaster was recommended for use in long-term work zones as the issues were considered and the working personnel can be better prepared with solutions. The CO2 cartridges should be tested for their functioning, and if not operational, the crew should have extra CO2 cartridges as a stand by. Research studies have reported false negatives due to the accumulation of ice between the CO2 cartridge and the firing pin, which produces a short burst of sound after the first use (Khan et al., 2019). The Caltrans engineers interviewed expressed the need to replace the CO2 cartridge being hazardous to the worker during the work zone operations and

169 the downsides of having a large number of false positives. The use of a SonoBlaster, Intellicone, and WAS, when placed strategically between AFAD systems, is expected to increase safety for motorists as articulated by Caltrans professionals interviewed. Furthermore, this setup would decrease the number of intrusions. Worker presence is needed to solely monitor the SonoBlaster regarding its functioning, addressing the issues and other problems. It was noted that the cumulative response rates through three SonoBlaster tests were 92% and 85% at 50 and 100 feet, respectively. As observed through the installation and activation processes, results proved to provide technology evaluation as “easy to use.” The alarm went off effectively and lasted around 13 seconds. The researchers also demonstrated to the trainees how the CO2 cartridges were changed and equipped for future usage. A vehicle traveling at roughly 20 mph collided with and successfully activated the SonoBlaster intrusion alarm (Gambatese et al., 2017). The audio levels can be adjusted, which is seen as a positive point by the Caltrans professionals. In another scenario, a SonoBlaster was rendered useless when it was run over by a vehicle and the CO2 cartridge was punctured without sounding the alarm. In other narrow work zone sites, the SonoBlasters were knocked over and false positives were recorded as the vehicles passed by in close proximity with the narrow work zone. Intellicone The Intellicone system is a PSA which is powered by motion sensitive and communications-based technologies. The device utilizes GPRS/GSM communications and GPS sensors. The Intellicone system serves as a communications-mediator between the system units in the field and the central command center. The system also includes a traffic management unit, Intellicone Unipart Dorman light (flashing lights unit), and a Sentry beam (vehicle sensor) ranging up to 3 feet. The system devices can be mounted on a traffic cone or channelizer using bolts. The electronic system can be mounted on cones which transmits the signals when impacted by a vehicle, producing auditory and visual alarms in the work zone. A description of the features of the Intellicone components is given in Table E5.2 (Traffic Worker Alert System, 2021).

170 Table E5.2. Intellicone components and features Component Description Features* Range Battery PSA Portable Site Alarm which connects to cones and TMU 3 tone siren, green and red flashing LEDs; Web portal reporting, Text Message Alerts, GPS location tracking RF: 50- meter range Internal rechargeable battery TMU Traffic Management Unit Web enabled to create large sites with multiple devices connected; Web portal reporting, Text Message Alerts, GPS location tracking RF: 50- meter range Internal rechargeable battery Intellicone Unipart Dorman ConeLITE Cone lamp with sensor which triggers the PSA when pushed, impacted, or tilted Communicates seamlessly with other lamps/sensors and Intellicone PSA; Deploys in any order and works day and night 50 meters max. between lamps Two 6 voltage type 4R25 batteries Intellicone Unipart Dorman SynchroGUIDE Lamp with intelligent wireless impact detection technology Communicates seamlessly with other lamps/sensors and Intellicone PSA; Deploys in any order and works day and night; Sequential flashing lamp 50 meters max. between lamps Two 6 voltage type 4R25 batteries Intellicone Sentry Beam Ultrasonic single ended sensor which triggers alarm when the emitted beam is breached Communicates seamlessly with other sensors and Intellicone PSA 30 meters max. of Intellicone PSA or TMU External 12V battery In one test, the PSA unit of the Intellicone was placed in the test work zone, approximately 50 feet away from the construction equipment. The Intellicone failed to activate after the car collided with the strobe, resulting in a false negative error. The strobes were turned off and on again, and the activity was repeated. The second time the alarm went off when the strobe hit the ground (Gambatese et al., 2017). At a distance of 0 feet, the Intellicone alarm sound is 100 decibels and drops dramatically to around 70 dB at 50 feet. From around 70 decibels at 50 feet to approximately 55 dB at 300 feet, there is no discernible difference in alarm decibel levels. The transmission rate of radio waves between the sensor and PSA is effective up to 100% up to 350 feet, while it is 0% at 450 feet. When the car impacts the sensors at 30 mph, the workers’ maximum median reaction time was roughly 1.22 seconds in response to the alarm, which had a mean duration of 20 seconds (Mishra et al., 2021).

171 AWARE The AWARE system is a radar-based system that can identify a potential work zone intrusion from several vehicles while also warning the errant driver and personnel who may be in danger. The system is comprised of a sensor that includes electronically-scanned radar, high-precision differential GPS, accelerometers, gyroscopes, and magnetometers for position and orientation sensing. To monitor traffic in the area, high-definition video and multiple wireless interfaces are used. When an intrusion is detected, a warning is sent out to the workers in the area (Asphalt Contractor, 2021). The AWARE system is currently being developed in two versions. The first is a lane incursion system that detects work zone intrusions, and the second is the Sentry, which is primarily intended for use by flaggers. The same components are used in both systems. The lane intrusion system, on the other hand, can be put on moving vehicles and equipment, whereas the Sentry is housed in a hard case that is fixed in place. The Sentry is made up of two parts: a sensor/alarm housing unit with a Raven radar sensor, LEDs, and an alarm speaker, and personal alarms called Worktrax (Mishra et al., 2021). AWARE monitors potential work zone invasions and notifies the workers in the work zone. AWARE is currently in the development stage and will not be commercially accessible until the manufacturer conducts additional field tests (Marks et al., 2017). AWARE can be adopted in short-term work zones operations that are less than a day, mobile in nature, and with a taper longer than or equal to 1,500 ft (Marks et al., 2017). A research study conducted by the Texas Transportation Institute evaluated the AWARE system for the manufacturer. The study findings indicate that, in the event of a lane closure, the AWARE system activates warning lights and an auditory alarm in a lane closure, flagging, tangent alignment, and lane closure during a right curve alignment and lane closure in a left curve alignment. When the system is tilted, the activation distances differ. The distance in the right curve is greater than the distance in the left curve. The device has a detection range of 500 feet. When the main alarm system is triggered within a range of 300 feet, Worktrax (the personal body alarm device) reliably produces vibratory and audio notifications. The AWARE’s internal stopping sight distance computations are precise enough to predict the alert’s timing (Theiss et al., 2017). According to MnDOT observations during AWARE testing, the system components were easy to deploy and can be effectively utilized in maintenance operations. The AWARE system is suggested for use in work zone maintenance operations.

172 6. WEARABLE LIGHTS Technology Description and Functions Wearable lights are worn by individual workers to enhance their visibility to oncoming drivers during nighttime work. Lights are available that can be worn on a hardhat, vest, or around a person’s arm or leg. The lights are battery powered, can emit one or multiple different colors (e.g., white, red, amber), and often can be set to either static or different types of flashing modes. A variety of different sizes and styles are currently available for purchase at a relatively low cost. Examples of different wearable lights that are available for use in construction include (Awolusi et al., 2018; Choi et al., 2017; Nnaji et al, 2020): • Guardian Angel, mountable/wearable light (https://www.guardianangeldevices.com/m/roadside-safety-light/) • 4id PowerArmz, lighted arm band (https://www.amazon.com/stores/4ID/page/C9CD471A-D1CA-4F44-865B- 1861FB360E3A?ref_=ast_bln) • VisionVest™, lighted safety vest (https://visionvest.com/) • Night Shift Safety Lights, shoe lights (https://www.nighttechgear.com/products/night- shift) • Halo Light™, hardhat-mounted light (https://illumagear.com/) The Halo Light™ by Illumagear (https://illumagear.com/) is an example of one type of wearable light. Studies have been conducted to evaluate the impact and performance of the Halo Light™, and as a result, it was the focus of this case study. The Halo Light™ is a personal lighting safety system that attaches to most hard hats. Halo Lights™ are hard hat compatible, lightweight, and cord-free task lighting which spread out powerful white light either as a 50-foot spotlight or 360-degree visible light for a quarter mile [2]. The Halo Lights™ are matte black colored compatible with any standard hard hat and is water resistant. For power, the light has a rechargeable battery and a battery charger. The Halo Light™ comes in different variants according to the intended use and are as follows: Halo SL White, Halo SL Amber Brake, and Halo SL Red Brake. The Halo Light SL has the following dimensions: 262 mm wide, 332 mm long, and 28.5 mm thick. The specifications for the Halo Light™ SL are provided in Table E6.1 (Illumagear, n.d.)

173 Table E6.1. Halo Light™ SL Specifications (https://illumagear.com/wp-content/uploads/2020/05/Specifications-Sheet.pdf) Characteristics Specifications Max. Light 360° mode: 276 lumens Spot Light 406 lumens Task Light 262 lumens Halo Light Weight 10 ounces Battery Weight 1.6 ounces Battery Type Single Lithium Ion 18650 cell; 3.5Ah Battery Life 1.5 - 121+ hours Water Resistant Submersion up to 1 meter for 30 minutes Dielectric Strength 30,000V (min) IP Rating IP 67, Dust proof & Water Resistant Illumination Modes: Halo Mode Hi-Alert Mode Task Mode Dim Mode 276 lumens, 25.64 foot-candle Fluctuating luminosity [The light keeps revolving in circular pattern with different intensity of the light] 259 lumens, 82.4 candela 49 lumens Power 7.2 volts @ 0.6 amps Dielectric strength 9000V minimum Safety Standards UL24, UL1638, UL 8750, IEC/EN 60598-1, IEC/EN 60598- 2-4, IEC/EN 62031, CSA9, CSA C22.2 No.9, CSA C22.2 No.250.13, FCC Part15-b Technology Applications, Set Up, and Use Safety concerns arise when there is a work environment that consists of a low level of lighting such as nighttime work. One common, consistent factor involved is the need to be seen in the nighttime or during low-light conditions to ensure the presence the visibility of workers by making them as visible as possible, and more productive by lighting their personal work space (Purdue ECT Team, 2015). To enhance safety on hazardous construction projects, such as work zones subject to unsafe driving behavior, distinctive topographical features that render poor visibility, and workers not being visible in the nighttime paving work zone areas, adequate lighting is required to prevent injuries and fatalities. Currently, the Halo Light™ falls under the umbrella of the wearable devices to enhance awareness of the worker presence in nighttime work zone activities. To prevent injury incidents, the Halo Light™ radiates light over the surrounding area to indicate the presence of the worker and the worker’s location. Many construction organizations utilize some form of wearable devices in nighttime work zones to conduct maintenance operations. Roadway lighting eases the task of pathway driving for the public road users through illumination of the pavement or use of wearable devices on the workers which helps the drivers to sense the direction of the road and allows them to see the structures along the roadway (Nnaji et al., 2020; ATSSA, 2013).

174 Another scenario where the Halo Light™ was used for the communication of worker presence to road users is during a natural disaster such as a storm, and during heavy rainfall where the workers had to clean up the debris off the road. Apart from the above application, the Halo Light™ has been used in various conditions and operations. One example of its use is during flagging operations using an automated flagging assistance device where there was a narrow (about 20-foot-wide) open road gradually decreasing to a 9-foot-wide lane low-light work zone operation. The workers felt that they were visible to the road users who were driving in the mountainous regions. The Halo Light™ is well-suited to all types of nighttime work zone operations. Technology Adoption Wearable lights are intended for use at night and can be worn in almost any work zone operation. With respect to work zone intrusions, the lights are intended to make drivers aware of the presence of the workers in the instance when an intrusion occurs. The current MUTCD manual offers minimum specifications for general nighttime work zone tasks, but it does not provide necessary information pertaining to the appropriate type, quantity, or configuration of lighting systems to use in work zones. The Halo Light™ is built for construction purposes, and can be installed in seconds on any hard hat. It weighs approximately as much as a typical headlamp and the weight is distributed evenly on the head. The Halo Light™ was made to survive in rough environments (Purdue ECT Team, 2015). Some wearable lights have different settings for different situations. For example, the Halo Light™ can be set to different illumination modes that distribute the light in different patterns. The modes are: halo mode, hi-alert mode, task mode, and dim mode. Halo mode emits the full brightness of the light for 360-degree which helps the worker to see and move around and perform a number of jobs around the site. Hi-alert mode provides a unique visual identifier to maximize the chance of the user being seen through the use of the flashing lights in a 360-degree spin around the light. This mode is useful for flagging operations in order to be visible to passing motorists and construction equipment operators in the work zones. For the task mode, the front third of the Halo Light™ illuminates with maximum brightness to light up the work space or task area in a darkened area. Lastly, dim mode provides a 360-degree ring of light where the user is in close proximity with other workers having a face-to-face conversation. The dim mode is less bright and easier to look at from a close distance than the brighter modes. Pre-Planning and Implementation Plan The following factors and guidelines should be considered when implementing the types of lighting technologies that are or may be suited for work zones, and are pertinent to the wide variety of lighting technologies, including Halo Lights™. 1. Mobile work zones, such as paving operations – As the work zone is mobile in nature, the length varies for the whole work zone activity for a single night, and this feature can serve

175 as input where the lighting system should be mobile in nature. In the case of Halo Lights™, it is mobile and lightweight in nature as well. 2. Stationary work zones – The duration of work zones can also affect the decision-making when selecting a work zone technology. For shorter work zone durations, trailer-mounted technology devices are suggested whereas for longer work zone durations, roadway illumination devices or a mobile lighting system are recommended. The Halo Lights™ serves it purpose for short- and long-term work zones. 3. Glare – Glare from the lighting systems should be at minimum for workers, motorists and vehicle users to attract the attention rather than to distract. For lighting systems that have severe intensity of lighting, glare can be reduced using a see-through sheet or by setting up the lighting system at the lower elevation of the median. 4. Light Trespass – During work zone operations in an urban environment, care should be taken to not illuminate the residential or private areas outside the right-of-way as doing so creates a pathway for road users and disturbs the area dwellers. The area can be shielded or cut off using other technologies, if needed. 5. Cost –Cost can be an intimidating factor depending upon the number of devices and the additional modifications needed to serve its purpose for work zone operations. Observed Technology Impacts and Effectiveness Virginia DOT workers were given a duty bag for use in a work zone that contained a Halo Light™, first-aid kit, EMT, flashlight, neon light arm bands, and additional items. The light bands along with the Halo Light™ magnified the presence of the workers in the work zone areas conducted in a mountainous region. The VDOT workers were happy with the performance of the Halo Light™ and they felt they were more visible in hazardous conditions. The Halo Light™ could be used in hazard situations occurring either in U.S. or other worldwide locations, and adapts to the conditions at hand. In one example, the light was used during a tree removal activity in a work zone, wherein the Halo Light™ made sure the workers were visible to the passing drivers who were far away. Some workers felt that the Halo Light™ is heavier than anticipated and cumbersome to wear as it does not fit on different hardhat styles, such as the task hardhat style. The benefits observed when using the Halo Light™ include: provides visibility at all times in all directions over 1/4th mile away; complete illumination to the task area as per worker’s peripheral vision; multiple rechargeable lithium ion batteries present and can be attached one-by-one to provide over 12 hours of illumination on full power; and the Halo Light™ fits almost on any hard hat. The observed impacts while using different modes of the Halo Light are: The halo mode emits the full brightness of the light for 360-degree which helps the worker to see and move around and perform a number of jobs around the site. Hi-alert mode provides a unique visual identifier to maximize the chance of the user being seen through the use of the flashing lights in a 360-degree spin around the light. This mode is useful for flagging operations in order to be visible to passing motorists and construction equipment operators in the work zones. For the task mode, the front third of the Halo Light™ illuminates with maximum brightness to light up the work space or task area in a darkened area. Lastly, dim mode provides a 360-degree ring of light where the user is in

176 close proximity with other workers having a face-to-face conversation. The dim mode is less bright and easier to look at from a close distance than the brighter modes (Purdue ECT Team, 2015). Based on the results of recent research studies, wearable lighting systems are especially suitable for use during work zone maintenance operations (Nnaji et al., 2020). According to pilot testing done by the researchers (Nnaji et al., 2020), there was high visibility when the Halo Light was turned on 30 meters away from the benchmark point while there were no other sources of lights present. In the presence of the balloon light and tower light 30 meters away from the benchmark point, the researcher was disguised as a worker and there was not much significant differentiation between the lighting systems and the Halo Light™. The results of the pilot test were favorable to the test where the Halo Light™ was visible during low-light conditions (Nnaji et al., 2020). Through another series of tests, in the first case, density technicians were given the Halo Light™ to wear during night shifts and the speed of the passing vehicles were recorded through traffic analyzers. The second case involved the use of sensors located upstream of the paver to record the vehicle speed. The results of the first and second tests depict not much change in the speeds when the Halo Light™ was turned on. There was a significant impact seen when other workers who wore a reflective vest were near a worker with a Halo Light™. In this case, the other workers were more visible to the motorists. The battery charge length varies and it is recommended to have extra batteries in case the Halo Light™ runs out of power (Nnaji et al., 2020). Barriers to Use and Limitations to Effectiveness Changes in weather conditions, such as the presence of fog, mist, and smoky air area contribute to poor visibility of the Halo Light™ and minimizes its visibility. Use during natural disasters such as flooding, snowfall, and heavy rainfall reduces the effectiveness of the Halo Light™ as it is susceptible to wear and tear at a faster rate than specified. When the workers were soaked and saturated by heavy rainfall, the Halo Light™ was not able to withstand the wet weather and gave way to moisture or water. Charging of the Halo Light™ batteries was seen as an issue. The Halo Light™ stays active while the battery is charged and taken care of, and the battery life weakens when not charged or used for a long time. Previous versions of Halo Light™ used a disposal battery, and the battery issue is rectified in the latest versions using rechargeable lithium ion batteries. Suggestion from VDOT employees interviewed included improved battery life, a ring that is more streamlined, and adaptability to fit on different styles of hardhats. VDOT employees felt that use of the Halo Light™ is not compatible when workers work during a storm to put fuel in different vehicles, and while running a chainsaw to remove tree debris. The VDOT staff interviewed recommended the workers use other sources of light, such as a light plant, for these types of operations.

Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research Get This Book
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Work zone intrusion technologies are available that provide an opportunity to prevent and mitigate vehicle intrusions into roadway work zones.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 322: Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research provides a comprehensive synthesis and evaluation of technologies that prevent and/or mitigate intrusions into work zones.

The document is supplemental to NCHRP Research Report 1003: Guide to Alternative Technologiesfor Preventing and Mitigating Vehicle Intrusions into Highway Work Zones.

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