SUMMARY

Implementation of Federal Highway Administration Proven Safety Countermeasures

State departments of transportation (DOTs) consider and implement various safety countermeasures on their transportation networks to improve transportation safety. The Federal Highway Administration (FHWA) Office of Safety provides a list of and resources for 28 proven safety countermeasures (PSCs) and suggests their use for state DOTs and other agencies, as these PSCs have been shown through research to help reduce fatalities and serious injuries on the nation’s roadways (https://highways.dot.gov/safety/proven-safety-countermeasures). FHWA groups these PSCs into five categories: speed management, pedestrian/bicyclist, roadway departure, intersections, and crosscutting. As the number of FHWA PSCs has grown from nine to 28, there is a need for a greater understanding of DOTs’ practices for their use.

This synthesis seeks to address the need for more knowledge regarding the practices of state DOTs for FHWA PSCs. The objective of the synthesis was to review and document state DOT practices regarding the implementation of the FHWA PSCs. The synthesis scope included

• FHWA PSCs piloted, implemented, or adopted as policy or procedures by DOTs;
• The extent, scale, and frequency to which each FHWA PSC has been implemented;
• Factors affecting different implementation approaches within a given state;
• DOTs’ evaluation of the FHWA PSCs after implementation;
• Barriers to the implementation of the FHWA PSCs and DOTs’ modifications and strategies to overcome those barriers; and
• Future research needs.

Attainment of the synthesis objectives involved three major tasks: a literature review, a survey of DOTs, and the development of case examples through follow-up interviews. Various sources such as guides, evaluation studies, websites, DOT policies and standards, and other resources were reviewed and compiled. An online survey questionnaire was distributed to all 50 DOTs and the District of Columbia DOT. Survey responses were received from 49 DOTs for a response rate of 96%. The survey included 14 questions and asked DOTs to categorize their implementation of each FHWA PSC according to five levels: Not Implemented, Development Stage, Demonstration Stage, Assessment Stage, and Institutionalized. After completion of the survey, follow-up interviews to develop case examples were conducted with the California, Minnesota, Nebraska, Nevada, Ohio, and Vermont state DOTs. In consultation with the topic panel, the criteria considered as a basis for choosing the DOTs for the case examples included

• Diversity of geography, level of experience, number and type of FHWA PSCs implemented, stages of implementation, customizations, and implementation challenges;

• Some preference for states with topic panel members; and
• Willingness to participate in a case example, as indicated in the survey (24 DOTs).

The literature review and survey identified various resources for FHWA PSCs. FHWA’s general webpage for FHWA PSCs (https://highways.dot.gov/safety/proven-safety-countermeasures) includes links to webpages for individual PSCs that provide information such as a general overview of the PSC, safety benefits, and related links. FHWA’s PSC resources are often consulted by DOTs during the development of safety projects. General information on FHWA PSCs is also available from some DOTs, such as California (https://dot.ca.gov/programs/safety-programs/proven-safety-countermeasures/countermeasures) and Florida (https://www.fdot.gov/Safety/safetyengineering/countermeasures).

DOTs have developed a wide range of resources, such as guidelines, standard drawings, implementation policies, selection charts or decision matrices, concept of operations, report templates, and public outreach materials for FHWA PSCs. Twenty-eight responding DOTs have developed policies, processes, procedures, or tools that consider and prioritize FHWA PSCs for implementation. Regarding PSC-specific resources for PSCs categorized as at Assessment Stage or Institutionalized by each DOT in the survey responses, responding DOTs have most frequently developed policies, standards, guidelines, or training materials for the following FHWA PSCs: implementation of longitudinal rumble strips and stripes on two-lane roads, SafetyEdge, and median barriers. Speed safety cameras (SSCs) and variable speed limits (VSLs) are the PSCs least frequently noted by responding DOTs as having resources developed.

DOTs have also conducted evaluation studies for FHWA PSCs and have discussed initiatives related to FHWA PSCs in their Strategic Highway Safety Plan (SHSP) and Highway Safety Improvement Program (HSIP) reports. Responding DOTs have most frequently conducted evaluation studies for the following FHWA PSCs: roundabouts, longitudinal rumble strips and stripes on two-lane roads, road diets, median barriers, and pavement friction management. As noted in the survey responses, no responding DOTs have completed evaluation studies for leading pedestrian interval (LPI), walkways or local road safety plans (LRSPs). DOTs often include pedestrians and bicyclists as an emphasis area in their SHSP reports, while other emphasis areas related to the FHWA PSCs include speeding, roadway departure crashes, and intersections.

DOTs implement a wide range of FHWA PSCs to various degrees, and all 49 of the DOTs that responded to the survey utilize FHWA PSCs to some extent. The number of Institutionalized FHWA PSCs per responding DOT varies from one to 27, and the FHWA PSCs that are most frequently Institutionalized by responding DOTs are longitudinal rumble strips and stripes on two-lane roads, median barriers, enhanced delineation for horizontal curves, and roundabouts. The most prevalent FHWA PSCs for the other implementation stages presented in the survey include

• Not Implemented: SSCs and VSLs;
• Development Stage: appropriate speed limits for all users and reduced left-turn conflict intersections;
• Demonstration Stage: LPI and corridor access management; and
• Assessment Stage: systemic application of multiple low-cost countermeasures at stop-controlled intersections and medians and pedestrian refuge islands in urban and suburban areas.

Overall implementation levels (based on averaging across all five implementation stages for each FHWA PSC) are the highest for longitudinal rumble strips and stripes on two-lane roads, roundabouts, and dedicated left- and right-turn lanes at intersections and lowest

for appropriate speed limits for all road users, VSLs, and SSCs. Responding DOTs deploy an average of 13.5 FHWA PSCs as standard practice. The FHWA PSCs that are most frequently implemented as standard practice by responding DOTs are longitudinal rumble strips and stripes on two-lane roads, backplates with retroreflective borders, yellow change intervals, and SafetyEdge. The most frequently considered FHWA PSCs that are institutionalized (but not standard practice for a given responding DOT) for use on projects are enhanced delineation for horizontal curves, roundabouts, and crosswalk visibility enhancements.

DOTs incorporate different approaches and strategies to implement and assess FHWA PSCs. Approaches used to implement FHWA PSCs include assessing cost effectiveness and achieving the highest reductions in crash fatalities and serious injuries, selecting treatment types instead of specific locations or specific projects, and analyses performed at a project-by-project specific level using HSIP application scoring criteria. Pilot projects are sometimes used when first implementing an FHWA PSC to evaluate its effectiveness and to assess state-specific implementation considerations such as public perception and design criteria. Approaches to implementation of FHWA PSCs differ based on different regions or areas of the state for 21 of the responding DOTs. Example practices used to assess the safety performance of FHWA PSCs include before-after studies, an ongoing contract in place to assess various traffic safety countermeasures, and informal observational data.

As part of their efforts to implement FHWA PSCs, DOTs utilize different types of funding mechanisms and pursue partnerships with local agencies for FHWA PSCs. Funding sources, which sometimes depend on the implementation stage of the PSC, include HSIP funds, state funds (pilot projects), maintenance funds, and project funds (FHWA PSCs that are standard practice). DOT partnerships with local agencies in implementing FHWA PSCs are pursued in various ways, such as providing them with resources, including them as stakeholders, assisting with LRSP development, promoting them through Local Technical Assistance Program (LTAP), and providing funding for local safety projects.

The synthesis also sought information regarding general and PSC-specific challenges faced by DOTs in their implementation of FHWA PSCs. Some of the general challenges noted by DOTs include staffing or funding constraints, getting buy-in for the safety research, pushback from internal staff and local agencies, outreach and education, public perception (especially for newer concepts such as reduced left-turn conflict intersections, bike lanes, and road diets), finding pilot projects, shifting to a proactive approach to safety, maintenance concerns, regulatory barriers, funding needs, the need for complementary PSCs to improve safety performance, and the lack of crash data on tribal lands. In general, implementation concerns are perceived by responding DOTs as the greatest challenge to the use of FHWA PSCs.

Regarding challenges to the use of specific FHWA PSCs, SSCs, VSLs, and appropriate speed limits for all road users were cited most frequently in the survey responses for having factors that hinder efforts to implement FHWA PSCs, while longitudinal rumble strips and stripes on two-lane roads and roundabouts were cited least frequently. Examples of challenges to the use of specific FHWA PSCs include

• SSCs and VSLs: implementation concerns and regulatory barriers (e.g., speed limits for VSLs being only advisory);
• Pedestrian Hybrid Beacons (PHBs): lack of public acceptance and understanding;
• Pavement friction management: experience with delamination and the need for additional information on safety benefits;
• Wider edge lines: paint shortages that led to higher costs for wider edge lines and inventory and tracking issues;

• Longitudinal rumble strips and stripes on two-lane roads: need for proper installation equipment;
• Backplates with retroreflective borders: not realizing safety benefits (possibly because of the standardization of signal equipment and features);
• Rectangular rapid flashing beacons (RRFBs), enhanced delineation for horizontal curves, systemic application of multiple low-cost countermeasures at stop-controlled intersections, and SSCs: performance of solar-powered traffic control devices in cloudy weather;
• Lighting: existing right-of-way constraints (e.g., sidewalks, utility poles); and
• Road Safety Audits (RSAs): implementing findings.

Twenty-nine responding DOTs indicated that they have not stopped using any FHWA PSCs. The following FHWA PSCs are no longer utilized by at least one responding DOT: appropriate speed limits for all users, SSCs, VSLs, PHBs, SafetyEdge, backplates with retroreflective borders, and pavement friction management. Responding DOTs noted stakeholder concerns as a factor in their decision to stop using each of these seven FHWA PSCs except for SafetyEdge. Other reasons cited include

• Appropriate speed limits for all users: results similar to current DOT processes;
• SSCs: the need for legislation;
• VSLs: increased emphasis on other safety countermeasures (SCs) or initiatives, cost to implement;
• PHBs: potential for driver confusion;
• SafetyEdge: lack of adequate pavement thickness, cost to implement;
• Backplates with retroreflective borders: increased emphasis on other SCs or initiatives, cost to implement, and need for more research regarding safety outcomes; and
• Pavement friction treatment: cost to implement, delamination issues, and adverse effects on pavement life cycle.

To address these challenges and overcome barriers to implementation, DOTs pursue various types of modifications or alternative strategies when implementing FHWA PSCs. The FHWA PSCs with the highest number of responding DOTs that have implemented modifications or alternative strategies are roundabouts and road diets. The most prevalent FHWA PSCs for each type of modification or alternative strategy are

• Physical changes: roundabouts;
• Change in approach or method to implement: appropriate speed limits for all road users, bicycle lanes, and backplates with retroreflective borders;
• Alternative delivery mechanisms or funding sources: systemic application of multiple low-cost countermeasures at stop-controlled intersections, enhanced delineation for horizontal curves, and backplates with retroreflective borders;
• Pilot projects: RRFBs, SSCs, VSLs, and road diets;
• Change in approach to public outreach: roundabouts, reduced left-turn conflict intersections, corridor access management, and road diets; and
• None: yellow change intervals, RSAs, and dedicated left- and right-turn lanes at intersections.

Strategies used to overcome implementation challenges for FHWA PSCs include, but are not limited to, involving maintenance personnel as stakeholders, enhancing public involvement efforts to get more engagement from stakeholders in the decision-making process, providing outreach and training, and being selective in the use of FHWA PSCs to help ensure success and avoid implementation challenges that could hinder future efforts. Example modifications to specific FHWA PSCs include revising standards for rumble strips and SafetyEdge, limiting the installation of rumble strips to new pavement, developing installation specifications for rumble strips, increasing the gap for centerline rumble strips

to avoid pavement joints, including gaps in rumble strips to accommodate bicyclists, modular roundabouts, sinusoidal rumble strips to address noise concerns, and bundling multiple locations for lighting improvements.

The synthesis also explored opportunities for the enhancement of practices for FHWA PSCs. As noted in DOT interviews, examples of ways DOTs are working toward enhancing their use of FHWA PSCs in the future include developing state-specific crash modification factors (CMFs), creating guidance for all 28 FHWA PSCs in one document, updating guidance for corridor access management to make it more prescriptive, providing local agencies with additional guidance on implementation, incorporating FHWA PSCs earlier in the project development process, implementing risk-based analyses, augmenting methods for regular assessment, finding ways to utilize pilot projects, increasing the use of PSCs at intersections, developing a pedestrian level lighting standard, expanding use of LPIs and developing guidelines for their use, and conducting a pilot study for a target speed program.

Opportunities suggested by these DOTs to enhance FHWA’s PSC initiative include providing additional information on average benefit-cost ratios for PSCs to help DOTs prioritize them based on level of impact, posting tables or data for all PSCs regarding CMFs and crash severity that are easily distinguishable and comparable for each PSC, adding information on conditions that may not be suitable for the use of specific PSCs, creating short informational videos on PSCs, and developing additional guidance for design and implementation of FHWA PSCs (including actionable steps). DOTs are also interested in learning about other state DOTs’ experiences with FHWA PSCs.

Finally, this synthesis has identified some gaps in existing knowledge and future research needs to enhance practices for the use of FHWA PSCs in the United States. Suggestions for future research include the following:

• Additional research studies could evaluate the safety performance of FHWA PSCs, especially for those PSCs with a limited number of existing evaluation studies or outdated evaluation studies (e.g., LPI, walkways, roadside design improvements at curves, lighting, and LRSPs).
• The development of a guidebook would provide direction and actionable steps for the implementation of FHWA PSCs. Potential topics for the guidebook could include implementation guidance, maintenance considerations, public outreach, funding, modifications or alternative strategies, and case studies.
• Additional tools and resources (e.g., benefit-cost assessment tools, maintenance guidance, technical assistance) to help support PSC implementation could be developed.
• Outreach materials for FHWA PSCs, especially those that incorporate newer concepts and may potentially encounter resistance from stakeholders (e.g., reduced left-turn conflict intersections) could be created.
• Enhanced guidance for FHWA PSCs related to speed management (appropriate speed limits for all users, SSCs, and VSLs) could be developed to provide strategies on how to overcome challenges such as regulatory barriers.
• A clearinghouse could be implemented that includes DOT and FHWA resources, evaluations, tables or data for all PSCs regarding CMFs and crash severity to facilitate comparisons, information on conditions that may not be suitable for the use of specific PSCs, short informational videos on PSCs, and examples of modifications or alternative strategies for FHWA PSCs to facilitate the sharing of knowledge among DOTs, metropolitan planning organizations, and local agencies.