Shared Automated Vehicle Toolkit: Policies and Planning Considerations for Implementation (2022)

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35   Implementing MOD and AVs will likely result in changes to rights­of­way access, curb­ space management, and roadway design. This chapter provides information on each of these topic areas. Tools for Rights-of-Way and Curbspace Management Tools included in this chapter: • Potential rights­of­way changes to account for AVs. • Possible curbspace management strategies that include AVs. • Roadway design changes to support AVs. Vehicle automation (in addition to MOD) may require changes in rights­of­way manage­ ment. Increasing vehicle automation for passenger and delivery vehicles (e.g., ADVs, freight delivery) may also increase competition for curbspace. Strategies for curbspace changes that may be needed include • Dedicating curbspace for different uses to address safety concerns (e.g., shared micromobility passenger and delivery loading zones), • Establishing flex zones (i.e., spaces with multifunctional purpose depending on the time of the day, including loading zones for people and goods during the day, parking at night) (Kraw­ czyk 2017), and • Increasing the number and size of passenger and delivery loading zones (Schlecter 2018). Adapting curbspace for other modes, such as MOD and AVs, can help increase goods access and mobility. Figure 8 illustrates an example of an 80­foot­wide street today with its existing uses. Figure 9 illustrates the same 80­foot­wide street with examples of how rights­of­way can be repurposed for multiple modes in conjunction with AVs. The figures demonstrate potential ways to repur­ pose the roadway, including • Replacing off­street parking with infill development, • Repurposing on­street parking and dedicated turn lanes for other uses and modes (e.g., pro­ tected bikeshared micromobility users), • Supporting the use of shared rides through passenger loading zones and high­occupancy vehicle (HOV) lanes, • Dedicating curbspace for shared micromobility parking, • Reducing the number of traffic lanes, and • Implementing flexible loading zones. C H A P T E R 5 Rights-of-Way and Curbspace Management

36 Shared Automated Vehicle Toolkit: Policies and Planning Considerations for Implementation Rights-of-Way Management AVs are being developed to operate under specific operational design domains (ODDs). ODDs are the environments in which an automated system is designed to operate (e.g., roadway types, weather, nighttime). As the levels of automation increase, AVs will be able to operate in all the areas and condi­ tions that human­driven vehicles currently operate. These ODDs include a variety of built environment types from high­density downtowns to outlying rural areas, dif­ ferent weather conditions (e.g., snow, fog), various climates (e.g., humid, rainy), and numerous infrastructure types (e.g., high­speed highways, single lane roads). Developing ODDs to include this range of environments could necessitate changes in the lane distribution on roadways. For example, HOV lanes on highways may need to become SAV­only lanes to mitigate congestion and/or decrease potential conflicts with human­driven vehicles. In addition, the use of bus­only lanes could potentially be shared with multipassenger SAVs. In addition to encouraging high­ occupancy rides, rights­of­way strategies could also help transportation agencies manage demand at peak locations and times (e.g., downtowns, large­scale events). Table 10 provides examples of potential lane classifications that can be applied to different multilane roadways (e.g., highways, local roads) after the introduction of AVs. SOURCE: Streetmix. Figure 9. Potential street and curbspace repurposing. SOURCE: Streetmix. Figure 8. Current rights-of-way use.

Rights-of-Way and Curbspace Management 37   Reclassifying vehicular lanes is not limited to occupancy­based characteristics. Non­ occupancy­based characteristics, such as vehicle purpose (e.g., goods delivery vehicles) could also be considered. Vehicular lanes could also be reclassified by operational characteristics (e.g., human­driven and HAVs). Figure 10 illustrates the current highway lane distribution on a typical urban freeway. Figure 11 and Figure 12 illustrate potential lane distribution strategies based on occupancy and operational characteristics, respectively. Lane assignments could vary based on operational characteristics, time of day (e.g., commute hours), location (e.g., intrastate and interstate roadways), and occupancy [e.g., one lane for zero­occupancy vehicles (ZOVs) and single­occupancy vehicles (SOVs)]. Appendix B: “Sample Policies” includes an example policy to alter the right­of­way to support innovative modes. Occupancy Characteristics Description Zero No driver or passengers in the vehicle. Fully automated vehicle driving to/from a parked location. Single One passenger in the vehicle. One passenger riding in a fully automated vehicle. One driver in the vehicle. One driver operating a non-automated vehicle. Delivery. ADV or freight vehicle carrying goods to be delivered. High- Occupancy Multiple passengers (2+). At least two passengers riding in a fully automatedvehicle; may or may not share destination and origin. Multiple passengers (2+). One driver and one or more passengers in a non-automated vehicle. Bus only. Lane reserved exclusively for use by public transit buses. Table 10. Potential lane classifications. Shared Spaces Program Due to the COVID-19 pandemic, in San Francisco, California, the city and county COVID-19 Economic Recovery Task Force developed the Shared Spaces Program (CBS Bay Area 2020). Shared Spaces allows business to apply for a permit to use a variety of outdoor spaces for business uses. Available outdoor spaces include curbspace sections, parking lanes, roadways, private property, greenspaces, and port areas (e.g., the piers). Each available space has its own requirements (e.g., a 6-foot-wide travel path must be kept available at all times). From May 2020 to August 2020, San Francisco received approximately 1,240 permit requests and approved 66% of these applications. San Francisco granted partial approval on 16% of requests. Twelve percent of these applications are either in review or pending application. Only 6% were denied during the same time period. Shared Spaces has allowed for the repurposing of the curbspace and rights- of-way for a variety of uses including outdoor dining, retail, and services (e.g., fitness classes) (City and County of San Francisco 2020). Curbspace changes, such as those supported by the Shared Spaces Program, could impact MOD and AV operations by reducing parking, changing loading availability, narrowing roadways, etc.

38 Shared Automated Vehicle Toolkit: Policies and Planning Considerations for Implementation Adapted from Madrona Venture Group (Stewart 2017). Figure 10. Current highway rights-of-way management. Adapted from Madrona Venture Group (Stewart 2017). Figure 11. Occupancy-based highway rights-of-way management.

Rights-of-Way and Curbspace Management 39   Road Design Changes Road design has been the focus of recent efforts to enable existing transportation infrastructure to support AVs. AVs will need to be able to recognize and understand elements of road design to operate and gain access to areas including road­ ways and curbspace (e.g., highway on­ramp markings, yellow­ colored curbs for passenger loading). Ensuring that roads are universally designed or adhere to similar standards can help with AV integration and safe operations. For example, the U.S. DOT publishes and updates the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) to define the standards road managers use when designing and installing devices on different roadways (e.g., highways, bike lanes, pedestrian walkways). However, states can choose to adopt the MUTCD with state variations. Uniformly designing roads to limit regional or state­ by­state variations and ensure that jurisdictions adhere to standards, such as those outlined in the MUTCD, can support AV integration. AVs will also need to connect to and communicate with each other and other infrastructure elements to safely access these spaces. For example, AVs will need to communicate with other AVs as well as human­driven vehicles that are merging from an on­ramp onto a highway. The development of AVs as connected vehicles (i.e., vehicles that can communicate with outside infrastructure elements and other vehicles) will require supportive infrastructure on roadways and other built environment features. Supportive elements could include road­ way sensors, internet connections, and databases to store and process communication data. In addition to facilitating the safe and efficient movement of and communication between AVs, updated road design practices will help facilitate rights­of­way management and further support multiple road users on the road. Elements such as pavement markings, signage, and pavement condition and configuration can encourage multiple users to safely share the roadway; these elements need to be considered when designing roadways for both the present day and Figure 12. Operational-based highway rights-of-way management. Adapted from Madrona Venture Group (Stewart 2017). The deceleration lane is separated from the travel lanes by a dotted and then a broken white line. These lane markings can help keep AVs from mistakenly drifting into the deceleration lane (FHWA 2017).

40 Shared Automated Vehicle Toolkit: Policies and Planning Considerations for Implementation the future. Other elements that ought to be considered include traffic signals, work zone traffic control devices, and special consideration for bridges and other weight­constrained facilities. Many organizations, such as the National Cooperative Highway Research Program (NCHRP), the American Association of State Highway and Transportation Officials (AASHTO), and the National Committee on Uniform Traffic Control Devices focus on the interaction of these ele­ ments and their relationship with AVs. These organizations are in part charged with improving the state of the practice by ensuring that the transportation system remains safe and efficient while also considering changing technologies. This includes providing the correct signage and markings across facility types and maintaining the correct sight distances for horizontal and ver­ tical curvatures as well as higher elevations as AVs enter the vehicle mix. The following sections summarize key considerations for these and other organizations and the future of road design and land use to support AV operations. Elements that must be considered include • Pavement markings, • Signage, • Traffic signals, • Work zone (traffic control devices), • Roadway pavement and configurations, and • Bridges. In addition to these design considerations, maintaining pavement markings (e.g., consistent lane marking reflectivity, maintenance, and brightness), painting crosswalks with black shadow paint to appear to be multidimensional, and marking road endings (e.g., shoulders of the road) can be helpful for AV operations. Pavement markings: Proper pavement markings are critical to the safe operation of trans­ portation facilities. The needs of AVs will differ from the current vehicle mix and make these markings even more important. Pavement markings are critical for AV onboard sensors that detect the markings to support lane awareness. These markings are also critical for AVs navi­ gating roadway changes when approaching a pickup/drop­off point or on­/off­ramps (see Fig­ ure 13). This is an area of ongoing research as the use cases of AVs and their impacts on land use are still being devised, and the existing standards for pavement markings are extended to include condition and maintenance best practices. Signage: The ability of AVs to read and interpret traffic signs is an important factor for their implementation into the existing transportation system. While there are efforts toward increas­ ing the role of in­vehicle data and mapping to mitigate the need for machine­readable signage, the fact that these signs need to be readable by human drivers needs to remain at the forefront of future roadway design—especially when land use has changed to account for AV operations. In addition, to support AV operations and signage reading, consistent signage will likely need to be developed and implemented across a variety of jurisdictions. Signage developments will also need to be maintained over time. Figure 13. Freeway off-ramp.

Rights-of-Way and Curbspace Management 41   SAV­only lanes and other use­restriction signage (e.g., no left turns) are critical for AVs and more traditional users. So, while digitizing these signs might be beneficial for AVs, especially in adverse weather conditions, signs need to remain fully readable by human drivers as well. Traffic signals: In the near term, the physical components of traffic signals are not envisioned to drastically change the nearby land use. However, intersections with connected infrastructure will have expanded capabilities to support both safety and mobility. The communication of signal phase and timing data to all users may better enable intersections to safely accommodate multiple transportation modes simultaneously. This form of communication is critical to the implementation and the full realization of the potential of AVs. However, for this level of communication and connectivity to become a reality, infrastructure readiness and consensus on the communication mechanism must be achieved. Placing these enhanced signals at consistent locations (e.g., at the same height over the lanes they correspond to) can be helpful for the operation of AVs and human­operated vehicles. These critical com­ munication and operations elements may also have an impact on land use adjacent to the signals (e.g., signals may need to be located near infrastructure for wireless internet connectivity). Work zone (traffic control devices): Work zone traffic control devices are temporary control measures and therefore have minimal impact on road design. However, as road design practices are updated, there still needs to be special considerations for such temporary traffic control measures. This is especially critical as AVs will be heavily reliant on work zone data and machine recognition of work zone traffic control devices (e.g., human flaggers directing traffic, the need to cross double yellow lines)—all occurring in a potentially changing (land use) environment, being navigated by multiple transportation modes. The U.S. DOT’s Work Zone Data Exchange (WZDx), a platform to unify work zone data exchange, could help provide AVs with informa­ tion about work zones. Today, real­time work zone data, particularly for short­term or mobile work zones, are lim­ ited and inconsistent. Moreover, real­time work zone data lack a common vocabulary and data format. However, efforts are underway in both research and practice to address these challenges and to provide guidance and resources to agencies to further data capture and sharing. As such efforts continue, it is again important that the data are accessible to both AVs and humans. Roadway pavement and configurations: AVs operating on unpaved roadways face a chal­ lenge in using sensors for lane identification and positioning. Unpaved roadways typically lack any physical or marked delineation of the physical roadway edge and centerline or lane lines. While approximately one­third of all roadway miles in the United States are unpaved, paved roadways carry about 99% of VMT in both rural and urban areas. Therefore, the impact that unpaved roads will have on the operation of AVs will be limited. However, the challenge of AVs navigating unpaved roadways disproportionately limits the ability of rural populations to take advantage of these services. Special attention should be paid to these areas, especially in instances where populations are more in need of AV services. Unpaved roadways can also be part of street revitalization efforts and mixed­used develop­ ments, where the roadway may be covered with materials other than asphalt or concrete (e.g., bricks). These revitalization efforts should consider the impact on AVs. Regarding roadway configuration, only 2% of the nation’s roadways are classified as limited access. However, these roadways carry approximately 63% of all VMT in the United States. As such, it is important that AVs can operate on these roadway facilities. However, careful con­ sideration may need to be given as to how best to meet the needs of the traveling public while considering how technologies might operate in different facilities.

42 Shared Automated Vehicle Toolkit: Policies and Planning Considerations for Implementation Bridges: When AVs become ubiquitous, they may enable more vehicles to fit on the roadway due to reduced headway. While this increased capacity may be beneficial as more vehicles can traverse the system, it also may prove problematic for bridges and other weight­constrained components of the roadway system. Key Takeaways • Current curbspace management practices may need to be altered to facilitate multimodal integration and accommodate MOD and AVs by replacing on­street parking with loading zones, reducing the number of traffic lanes, etc. • Rights­of­way access may also need to be altered based on roadway (e.g., location), opera­ tional (e.g., time of day), or vehicle (e.g., SOV) characteristics. • Road design practices (e.g., signage, pavement configurations) will need to be updated to effectively support MOD and AVs, as the transportation system will need to support both human and machine drivers.