Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections: Supplement to NCHRP Report 613 (2008)

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APPENDIX E

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process Appendix E Prioritizing Treatments E.1 OVERVIEW This Appendix describes the research team’s approach to considering the range of potential treatments, the published effectiveness of the treatments, and the professional judgment on the expected effectiveness of each treatment, independent of the extent of published information that was available. The research team reviewed the literature review results to prioritize those treatments that were documented as having the ability to reduce speeds. Based on the team member’s professional experience and expectation for treatment effectiveness, each member ranked the treatments. During a work session, team members discussed their reasoning and ranking for each treatment. From these discussions, the team developed a consensus ranking of the expected effectiveness of each treatment. This ranking process is detailed in subsequent subsections of this text. Ultimately, the team correlated its consensus ranking with results of the highway agency survey responses to recommend specific treatments for testing in Phase II. This discussion is detailed in the subsequent sub section “Testing Program Approach.” E.2 LITERATURE REVIEW FINDINGS E.2.1 Overall Findings Through the literature review, the research team found a significant amount of information associated with speed characteristics and factors that affect speed. In reviewing this information, it was clear there is little quantifiable data on those factors. Of that information, there is little quantifiable data about measurable speed reduction performance at intersections in general and specifically at high-speed locations. Similarly, there is an extensive amount of information about roadway intersection safety but little direct correlation between safety and speed, especially at intersections. There are a variety of potential speed reduction treatments used domestically and internationally. Unfortunately, there is little quantifiable data about their effectiveness. Where safety considerations or performance of a particular treatment has been documented, the role of the speed reduction of the treatment is often not clear. These apparent gaps in quantifiable information may help in prioritizing potential testing applications It is intuitive that some speed reduction information for segments would have potential applications at intersections. Phase II testing should help identify relationships between segment speeds and intersections and how speed reduction treatments could be applied. The safety affects of speed reduction treatments at high-speed intersections will require a number of years to monitor conditions after the treatments have been implemented. Therefore, Phase II testing results will focus on quantifying speed reduction for specific treatments. Kittelson& Associates, Inc. Page E-1

Appendix E NCHRP 3-74 Selection Process Selection of Speed Reduction Treatments at High-Speed Intersections EE.2.22 Potential Speed Reduction Treatments Considering the variety of potential speed reduction treatments, there are a variety of scenarios that will help guide the research team in developing the guidelines and testing plan. Exhibit E-1 shows a range of potential scenarios and corresponding actions that might guide development of a testing program. Exhibit E-1 Possible Scenarios Scenario Potential Action A treatment has shown to be effective at reducing speeds • Quantify predicted speed reduction • Determine potential side effects • Identify conditions for application A treatment has shown to be ineffective at reducing speeds • Remove from consideration as potential speed reduction treatment recognizing it may be beneficial in other ways, such as wider longitudinal striping improve visibility A treatment lacks documentation on its potential effectiveness • Consider the potential of this treatment to reduce speed • If potential is high, consider for testing An agency intends on implementing a treatment with unknown effectiveness • Consider this agency as a possible testing candidate • Document findings E.2.33 Research Team Treatment Ranking The research team rated and ranked each prospective treatment as a first step in prioritizing treatments for testing in Phase II. Upon clarifying some base assumptions for some of the treatments, the research team created simple, qualitative ranking criteria that included: expected speed reduction effectiveness, ease of implementation, and low side effect potential. Expected speed reduction effectiveness considered anticipated speed reduction and not the expected safety benefits associated with treatments. The ease of implementation criterion was meant to encompass only construction and design efforts of a particular treatment. Low side effect potential included maintenance requirements and negative impacts to safety, multimodal users, or the roadway environment that could result from a particular treatment. The research team recognized the criteria varied in level of importance for these ranking purposes; therefore, weights were applied to the criteria. Expected speed reduction effectiveness received 60 percent of the weight, low side effects received 30 percent of the weight, and ease of implementation received 10 percent of the weight. The team recognized these values were subjective. However considering the lack of published data on the speed reduction of potential treatments, the team prioritized the treatments to test their actual effectiveness at reducing speeds. The research team understood that ease of implementation is an important consideration; however, easy-to-implement treatments such as wider longitudinal striping have little to no published speed reduction qualities. Each team member ranked the treatments, based on his or her professional experience and Page E-2 Kittelson & Associates, Inc.

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process expectation for treatment effectiveness, based on the literature review results. During a work session, team members discussed their reasoning and rankings for each treatment. From these discussions, the team developed a consensus ranking of the expected effectiveness, ease of implementation, and side effects of each treatment. Exhibits E-2, E-3, and E-4 present research team consensus ranking and a summary of team comments. Kittelson& Associates, Inc. Page E-3

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process Exhibit E-2 Research Team Consensus Ranking Weight: 6 1 3 Number Treatment Expected Speed Reduction Effectiveness Ease of Implementation Low Side Effect Potential Un-weighted Total Weighted Total 1 Roundabouts (uncontrolled) 5 1 4 3.3 4.3 2 Speed tables (uncontrolled) 5 3 3 3.7 4.2 3 Approach reverse curvature (uncontrolled) 5 2 3 3.3 4.1 4 Rumble strips (stop) 4 4 4 4.0 4.0 5 Transverse pavement markings (stop) 3 4 4 3.7 3.4 6 Dynamic warning signs-speed (uncon.) 3 4 4 3.7 3.4 7 Splitter islands (stop) 3 3 4 3.3 3.3 8 Dynamic warning signs-conflict (uncon.) 3 3 4 3.3 3.3 9 Gateways (stop) 3 3 3 3.0 3.0 10 Dynamic warning signs-speed (stop) 2 4 4 3.3 2.8 11 Reduced lane width (uncontrolled) 3 3 2 2.7 2.7 12 Visible shoulder treatments (stop) 2 3 4 3.0 2.7 13 Visible shoulder treatments (uncontrolled) 2 3 4 3.0 2.7 14 Landscaping (uncontrolled) 2 3 4 3.0 2.7 15 Dynamic warning signs-conflict (stop) 2 3 4 3.0 2.7 16 Wider longitudinal markings (stop) 1 5 5 3.7 2.6 17 Wider longitudinal markings (uncontrolled) 1 5 5 3.7 2.6 18 Reduced lane width (stop) 2 3 3 2.7 2.4 19 Roadside design features (stop) 2 3 3 2.7 2.4 20 Roadside design features (uncontrolled) 2 3 3 2.7 2.4 21 Landscaping (stop) 1 3 4 2.7 2.1 Rating (5=best, 1=worst) Kittelson& Associates, Inc. Page E-4

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process Exhibit E-3 Research Team Consensus Ranking for Stop-Controlled Approaches Treatment Research Team Rank Category Research Team Comments Rumble Strips 1 Physical • Potential Side Effects o Noise pollution o Maintenance issues in snow areas, such as snow plowing. o Maintenance issues with debris collection Transverse Pavement Markings 2 Visual • Potential Side Effects o Similar maintenance issues as conventional pavement marking, such as paint breaking up. o Potentially more maintenance needs than wider longitudinal pavement marking or other markings because these are actually being driven over by vehicles. o Can create a slick surface for motorcycles or bikes Splitter Islands 3 Visual, Physical • Purpose is to cause horizontal deflection Gateways 4 Visual, Physical, Operational • More effective if used to give the illusion of a physically constrained roadway. o Limiting the sight distance • Does this give a driver a message to slow down (signing) or does it actually scare the driver into reducing their speeds? • Possible assumptions o Physical change o Environmental change o Aesthetics o Applied to other treatments • Potential Side Effects o Narrowing roadway may be seen as a safety hazard by some agencies. o Potential distractions for drivers o Roadside safety concerns • At a stop-controlled approach the driver will already be slowing down to complete a stop, will a gateway really affect the speed profile at which they approach? Dynamic Warning Signs – Speed 5 Visual, Operational • If placed at the intersection, it may be too late to be effective. Therefore, advanced placement may be more effective. • Possibly used in conjunction with other treatments • Warning may only appear if certain maximum speed thresholds are exceeded • Signs that appear at specific threshold speeds would be more effective than signs that stay on continuously. • Ease of Implementation o Requires power supply for sign, radar, loop detectors o Increase in maintenance of loop detectors or other detectors. Visible Shoulder Treatments 6 Visual • Drivers would be less likely to notice visible shoulder treatments on higher speed facilities. • Shoulder treatments could be used to alert drivers of a change in cross section. • At a stop-controlled approach the driver will already be slowing down to complete a stop, will shoulder treatments really affect the speed profile at which they approach? • Potential Side Effects o Different colors may have different freezing and thawing effects o Potential hazard for bikes o If lane width is reduced, may be tracked by trucks and buses • Ease of Implementation o Can consist of a wide variety of projects, such as colored pavement, texture, vegetation, and rumble strips. Dynamic Warning Signs – Conflict 7 Visual, Operational • If a driver is already going to stop at the approach, is this treatment really necessary? • If drivers see that there are no conflicting cars present, this may encourage them to violate the stop control. • Ease of Implementation o Requires power supply for sign, radar, loop detectors o More complicated than speed monitoring signs because of loop detectors or other vehicle detectors. o Increase in maintenance of loop detectors or other detectors. Wider Longitudinal Pavement Markings 8 Visual • There may be other reasons that this treatment is used beyond speed reduction, such as increased visibility in general and older drivers specifically. • At a stop-controlled approach the driver will already be slowing down to complete a stop, will pavement markings really affect the speed profile at which they approach? • Potential Side Effects o Similar maintenance issues as conventional pavement marking, such as paint breaking up. Reduced Lane Width 9 Visual, Physical, Operational • Does this treatment provide a visual illusion of a constrained roadway or does this physically constrain the roadway? • Difference in effectiveness between major road vs. minor road • The effective width and length of reduced lane width has not been determined. • Potential Side Effects o Narrowing roadway may be seen as a safety hazard by some agencies. o Less severe at stop control approaches because the driver is already slowing down. • Ease of Implementation o Depends on the type of lane narrowing. Re-striping would be easy, but physical reduction in cross section would be more difficult. o What is easy may not be the most effective. Roadside Design Features 10 Visual • Assumes drivers are complying with stop control o Not as effective at stop control approach, because the driver is already slowing down to stop. o Would a driver really notice roadside features when they are concentrating on stopping? • If there are problems with control violation, this treatment could encourage compliance. • Roadside features give an overall message to the driver. • Potential Side Effects o Fixed object hazard Landscaping 11 Visual • At a stop-controlled approach the driver will already be slowing down to complete a stop, will landscaping really affect the speed profile at which they approach? • Potential Side Effects o Maintenance o Fixed object hazard Kittelson& Associates, Inc. Page E-5

Appendix E NCHRP 3-74 Selection Process Selection of Speed Reduction Treatments at High-Speed Intersections Exhibit E-4 Research Team Consensus Ranking for Uncontrolled and Yield Control Approaches Treatment Research Team Rank Category Research Team Comments Roundabouts1 1 Physical, Operational • Placing an object in the middle of the intersection would have a greater effect. • Where is the speed reduction taking place? Start of splitter island, R0, or R1? • Potential Side Effects o Requires a lot of right-of-way to implement o Expensive Speed Tables 2 Visual, Physical • No speed table applications have been found for high-speed facilities. • European example: Plateau combined with yield control. No information on effectiveness or applications. • Speed tables dictate a maximum speed due to the vertical deflection. What is the appropriate maximum speed to design for? • Potential Side Effects o Lower emergency response o Increase travel time of buses o Maintenance – drainage • Ease of Implementation o May require maintenance of traffic, such as diverting or re-routing traffic during construction. Approach Reverse Curvature 3 Physical, Operational • Potential Side Effects o Over tracking into the bike lane or shoulder o General safety concerns of introducing a curve into the roadway Dynamic Warning Signs – Speed 4 Visual, Operational • If placed at the intersection, it may be too late to be effective. Therefore, advanced placement may be more effective. • Possibly used in conjunction with other treatments • Warning may only appear if certain maximum speed thresholds are exceeded • Signs that appear at specific thresholds would be more effective than signs that stay on continuously. • Ease of Implementation o Requires power supply for sign, radar, and loop detectors o Increase in maintenance of loop detectors or other detectors. Dynamic Warning Signs – Conflict 5 Visual, Operational • More effective at this type of approach because it would actually caution drivers to reduce their speeds if they saw a conflicting car was present. • Ease of Implementation o Requires power supply for sign, radar, loop detectors o More complicated than speed monitoring signs o Increase in maintenance of loop detectors or other detectors. Reduced Lane Width 6 Visual, Physical, Operational • More effective if there is a change in roadway width at a particular roadway location, versus a continuous narrowing roadway. • More effective if the reduced lane width includes physical reduction in width, versus re-striping a narrower lane. • The effective width and length of reduced lane width has not been determined. • Potential Side Effects o Narrowing roadway may be seen as a safety hazard by some agencies. o More severe at uncontrolled approaches than stop-controlled intersections. • Ease of Implementation o Depends on the type of lane narrowing. Re-striping would be easy, but physical reduction in cross section would be more difficult. o What is easy may not be the most effective. Visible Shoulder Treatments 7 Visual • More effective if there is a change in roadway width at a particular roadway location, versus a continuous narrowing roadway. • Does this give a visual illusion of a constrained roadway or does this physically constrain the roadway? • Visual vs. Physical • Potential Side Effects o Different colors may have different freezing and thawing effects o Potential hazard for bikes o If lane width is reduced, may be tracked by trucks and buses Landscaping 8 Visual • More effective if there is a change in roadway width at a particular roadway location, versus continuous landscaping along the entire roadway. • Potential Side Effects o Maintenance o Fixed object hazard Wider Longitudinal Pavement Markings 9 Visual • More effective at this type of approach because there would be more time and distance to notice the striping. • There may be other reasons beyond speed reduction that this treatment is used for. Such as, increase visibility, older drivers. • Potential Side Effects o Similar maintenance issues as conventional pavement marking, such as paint breaking up. Roadside Design Features 10 Visual • Roadside features give an overall message to the driver. • More effective at this type of approach because the driver would have more time to become effected by the environment. • Does the size of treatment affect the effectiveness? • What are the distinguishing features between roadside features and landscaping? • Urban vs. rural environment • At what distance from the roadway are these treatments placed? o Are roadside design features as effective as shoulder treatments, when they are farther away from the roadway? • Potential Side Effects o Fixed object hazard 1 Approaches to roundabouts are yield control. Page E-6 Kittelson& Associates, Inc.

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process E.2.4 Integrating State Survey Results Cooperation with state agencies will be a critical means of implementing a successful testing program of speed reduction treatments. States that are considering testing programs can help leverage Phase II testing funding, assuming the agencies implement the treatments. The results of the survey are presented in Chapter 2. The survey results indicated a number of states have an expressed interest in participating in studying the effectiveness of potential treatments. Question 7 of the state agency survey allowed state agencies to share their input about what speed reduction treatments they felt were most important to be evaluated to determine a level of effectiveness. Question 11 investigated the number of states that would be interested in participating in an effectiveness evaluation of speed reduction treatments at intersection approaches to be installed in 2005. The research team integrated the information gathered from the state agency survey to determine the relationship between the interest of the states and the research team treatment ranking. Determining the actual treatments to be tested would require ongoing coordination with the agencies. In some cases, the research team has a high interest in treatments that are of low priority to the states. Similarly, the states are interested in testing treatments that are a lower priority to the research team. The value and logic of testing treatments each group rates of high value and interest is obvious; but there can be value in considering those areas where the priority or interest is different. In situations were states are interested in testing a treatment that is a lower priority than the research team, potential testing may validate the speed reduction effectiveness of a treatment. Similarly, testing treatments that are of interest of the research team (and not the states) could provide insights about countermeasures with which the states had little experience. Exhibit E- 5 shows the various testing objectives that may help direct the testing of potential treatments. Exhibit E-5 Testing Objectives Organization Priority/interest Testing Objectives State Agency High Research Team Low Validate effectiveness of current state agency program. State Agency High Research Team High Determine and quantify effectiveness. State Agency Low Research Team High Validate treatments that states may not have considered. In Phase II, further activities would focus on confirming what types of treatments agencies plan on testing and when they plan to implement these treatments. Further coordination will help determine the number of potential test sites for each type of treatment. Depending on the number of potential test sites, the team can determine the confidence level of the results for each treatment test. Kittelson& Associates, Inc. Page E-7

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process E.2.5 Comparing Treatment Priorities Selecting potential treatments for testing considers the research team and state agency priorities and interests for implementing a treatment. The research team consensus ranking was categorized as “high” (ranked 1-4), “medium” (ranked 5-8), and “low” (ranked 9-21). These categories were developed looking at natural breaks in the weighted values for each treatment. Similarly, the research team reviewed the number of state responses for interest and priorities for implementing treatments in 2005. The state responses for a particular treatment were categorized as “high” (9-6 states), “medium” (5-4 states), and “low” (3-0 states). These categories were established by considering natural breaks in the state responses. This exercise was not a direct comparison and served as a means of correlating the differing information to aid in prioritizing treatments. The research team considered and evaluated potential treatment rankings for their expected effectiveness at uncontrolled and stop/signal-controlled intersection approaches. The states did not make this distinction; however, the concept provides helpful guidance in recommending treatments for testing. Because of this difference in considering treatments, the dynamic warning signs fell into more than one “high”, “medium”, or “low” category. The research team ranked dynamic warning signs activated by speed and conflicting vehicles a low ranking at stop/signal-controlled approaches and a medium ranking at uncontrolled approaches Exhibit E-6 compares the treatment type, its rating category, comments, and recommendations for testing. Page E-8 Kittelson & Associates, Inc.

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process Exhibit E-6 Comparing Agency and Research Team Treatment Priorities Treatment State Agency Usage Research Team Estimated Effectiveness for Speed Reduction Research Team Comments Rumble Strips HIGH HIGH • Consider testing this treatment because of the high interest by state agencies? • Considerable past research on the effectiveness of this treatment. Is this information sufficient to preclude testing? • Are states implementing this because of policy guidelines or because they want to determine their effectiveness? Wider Longitudinal Pavement Markings HIGH LOW • This treatment was ranked very low by the research team, but many states are interested in implementing this treatment. • States are using this treatment with little knowledge about its effectiveness. Therefore, testing could determine if it really is effective. • Are states implementing this treatment to reduce speeds or for other reasons, such as increasing the visibility of markings. Reduced Lane Width MEDIUM LOW • States have shown interest in implementing this treatment, but this treatment was not ranked very high by the research team. • Type of lane reduction • Re-striping • Physical change in cross section Roundabouts MEDIUM HIGH • Should roundabouts be a central focus of our study? • Roundabout projects are large and long term • Requires coordination with NCHRP 3-65 or other research. • Opportunities to coordinate with state agency contacts • Washington, Maryland, Kansas, Iowa, Arizona? Roadside Environment MEDIUM LOW • No discussion Transverse Pavement Markings MEDIUM MEDIUM • Transverse pavement markings could be applied to the shoulder or on the traveled way. • These are good treatments to test because it matches our lack of knowledge with the interest of the states Dynamic Warning Signs activated by speed of vehicle MEDIUM MEDIUM* • These are good treatments to test because it matches our lack of knowledge with the interest of the states Visible Shoulder Treatments MEDIUM LOW • No discussion Dynamic Warning Signs activated by conflicting vehicle LOW MEDIUM* • These are good treatments to test because it matches our lack of knowledge with the interest of the states Approach Reverse Curvature LOW MEDIUM • This treatment can consist of horizontal curvature on the approach or reverse horizontal curvature on the approach. • This treatment may be appropriate to test the effectiveness of applying roundabout-like treatments to conventional intersections. • This treatment may become the focus for a longer term, larger scale testing Speed Tables LOW HIGH • No states reported any plans for implementing this treatment in 2005. • This treatment was ranked high by the research team. Splitter Islands LOW MEDIUM • No states reported any plans for implementing this treatment in 2005. • This may not have been considered by states as a speed reduction treatment. • This treatment may have been categorized by states as a roundabout-like treatment. *The research team ranked dynamic warning signs activated by speed and conflicting vehicles a LOW ranking at stop-controlled approaches and a MEDIUM ranking at uncontrolled approaches Kittelson& Associates, Inc. Page E-9

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process E.2.6 Selecting Treatments for Testing The state highway agency interest for treatment implementation in 2005 and agency opinions of treatment evaluation importance was balanced with the research team judgment to develop three testing priority groupings. Table 7 illustrates the primary, secondary, and alternative treatments that were considered for testing. The primary list includes research team and state agency “high” rankings, as depicted previously in Table 6. The secondary list includes those treatments that were ranked “medium” by the research team and state agencies. Alternatives treatments are those receiving a “low” and “medium” by either the research team or state agency. Exhibit E-7 Priority Groupings of Treatments Treatment State Agency Usage Research Team Estimated Effectiveness for Speed Reduction Consider For Testing Rumble strips HIGH HIGH X Roundabouts MEDIUM HIGH X Speed tables LOW HIGH X Approach reverse curvature LOW HIGH X Primary Wider longitudinal pavement markings HIGH LOW X Transverse pavement markings MEDIUM MEDIUM X Secondary Dynamic warning signs – speed MEDIUM MEDIUM X Reduced lane width MEDIUM LOW Visible shoulder treatments MEDIUM LOW Roadside Environment MEDIUM LOW Splitter islands LOW MEDIUM Alternative Dynamic warning signs - conflicting vehicles LOW MEDIUM Priority grouping is the starting point, but final recommendations are based on additional consideration including state testing programs and state importance rankings. Finally, the research team applied its judgment to consider factors such as coordination with other research activities or prior experience. The following discussion presents considerations for primary and secondary treatments. E.2.6.1 Rumble Strips According to state highway agencies, rumble strips are one of the most important treatments to be evaluated for speed reduction effectiveness. The state agency survey also indicated there are nine states that have interest in implementing rumble strips for testing in 2005. The research team has a strong interest in testing this treatment based on the apparent expected performance of this treatment documented in the literature review. Therefore, the research team recommends this treatment for testing in Phase II. Kittelson& Associates, Inc. Page E-10

Appendix E NCHRP 3-74 Selection Process Selection of Speed Reduction Treatments at High-Speed Intersections E.2.6.2 Roundabouts Because of other ongoing research on roundabouts, the research team recommends focusing the proposed research on conventional at-grade intersections. NCHRP 3-65 Applying Roundabouts in the United States will provide a comprehensive summary of roundabout operations and safety performance. NCHRP 3-65 has collected spot speed data at existing roundabout locations throughout the nation. The data has been collected for locations 200 feet before the entrance of the roundabout, at the entrance, and at the exits of the roundabouts. Due to the other on-going research activities the research team does not recommend testing roundabouts in Phase II. However, future research could evaluate NCHRP 3-65 speed data for opportunities to evaluate speed performance. E.2.6.3 Speed Tables There is extensive information and interest about speed tables and their impact on safety and speed. However, much of the information relates to segment, roadway volumes, or roadways with operating speeds less than 45 mph. There is has been no published research or testing results for speed table applications on high-speed facilities or specifically at intersection approaches. Therefore, the research team recommends future studies to explore speed table applications on lower speed facilities. With and understanding of applications on low speed facilities, future testing could consider a broader application to facilities with higher speeds. E.2.6.4 Approach Reverse Curvature Approach reverse curvature was not ranked high by the states as far as interest in implementation or importance for testing. However, the research team observed that many of the speed reduction principles used to design modern roundabouts (deflected paths) could be applicable to conventional intersection approaches. The FHWA publication Roundabouts: An Informational Guide highlighted concepts of introducing curvature to reduce approach speeds at roundabouts. These concepts could form the basis for applications at conventional intersections. Therefore, the research team recommends this treatment for testing in Phase II. E.2.6.5 Wider Longitudinal Pavement Markings The research team consensus ranking revealed a low interest in testing wider longitudinal pavement markings. However, six state agencies have expressed interest in implementing this type of speed reduction treatment for testing in 2005. Wider longitudinal pavement markings could have benefit in increasing the visibility of the roadway segment and intersection striping. However, there is no indication that wider markings reduce speed. Therefore, the research team does not recommend this treatment for testing in Phase II. E.2.6.6 Transverse Pavement Markings Transverse pavement markings were ranked high by the states as far as importance for testing this treatment. In addition, five states have expressed plans for implementing this treatment in 2005. The research team consensus ranking revealed a medium interest in testing. However, Page E-11Kittelson & Associates, Inc.

NCHRP 3-74 Appendix E Selection of Speed Reduction Treatments at High-Speed Intersections Selection Process because of the high interest by the states, plans for implementing this treatment in 2005, and the results of the literature review, the research team recommends this treatment for testing in Phase II. E.2.6.7 Dynamic Warning Signs – Speed Dynamic warning signs activated by vehicle speed received the highest ranking by states in terms of importance and five states have expressed plans for implementing this treatment in 2005. The research team consensus revealed a medium interest in testing. Because of the high state interest and results of the literature review, the research team recommends this treatment for testing in Phase II. E.2.7 Number of Treatments Determining the number of treatments relies on balancing the number of potential treatments and the number of test sites per treatment. If too few treatments were tested, there would be limited quantifiable data on a variety of treatments. If too many treatments are selected, there could be insufficient resources to conduct an adequate testing plan. The number of test sites per treatment affects the validity of the testing results and the testing costs. Increasing the number of test sites per treatment increased the confidence of the test results but raises the testing budget. Testing conducted in cooperation with agency treatment implementation plans creates the best opportunity to leverage NCHRP and agency funding. Exhibit E-8 provides a means of considering the number of treatments that can be tested within the present NCHRP funding for Phase II. The table allows a variety of “what-if” scenarios to be considered depending on the types of treatment being implemented, their relative proximity for efficient data collection, and the number of treatments selected and the number of sites tested. This planning level tool can be modified to consider the need to testing budget reserves should a supplemental testing contingency be desired to review or retest specific treatment types. After considering the potential budget issues, it appears that three to five treatments might be able to be tested in Phase II. These numbers would be refined upon consultation with the Panel and further coordination with the state agencies implementing projects in the next year. Kittelson& Associates, Inc. Page E-12

Appendix E NCHRP 3-74 Selection Process Selection of Speed Reduction Treatments at High-Speed Intersections Exhibit E-8 Sample Testing Budget TREATMENT TESTING BUDGET Cost Per Test Activity Time (hours) Cost ($/hr) Total Cost ($) Coordination with State Agencies 24 100 $2,400 Testing Set-up 80 100 $8,000 Conduct Testing 80 100 $8,000 Summarize Testing Results 40 100 $4,000 Final Coordination and Final Report 8 100 $800 Additional Miscellaneous Expenses $3,000 Total Cost Per Test $26,200 Number of Treatments Tested: 4 Number of Test Sites per Treatment: 3 Total Cost for Testing Plan $314,400 Guidelines Preparation $50,000 Finalize Testing Plan $15,000 Total Cost of Phase II $379,400 Estimated Budget for Phase II $392,199 Page E-13 Kittelson & Associates, Inc.