National Academies Press: OpenBook

Systemic Pedestrian Safety Analysis (2018)

Chapter:Chapter 13 - Conclusion: Considerations and Limitations

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Page 74
Suggested Citation:"Chapter 13 - Conclusion: Considerations and Limitations." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.
Page 75
Suggested Citation:"Chapter 13 - Conclusion: Considerations and Limitations." National Academies of Sciences, Engineering, and Medicine. 2018. Systemic Pedestrian Safety Analysis. Washington, DC: The National Academies Press. doi: 10.17226/25255.

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74 A robust process has been outlined in this guidebook, one in which agencies can put to use high quality data to analyze pedestrian safety risks, identify the types of locations most associated with those problems, and select appropriate countermeasures for systemic implementation. The anticipation is that the guidebook can provide concrete guidance, real-world examples, and links to key additional references to help motivate and support agencies to gather the minimum level of data and technical expertise needed to perform the steps in a systemic process. Other steps may involve putting partnerships in place (e.g., with data stakeholders or other state and/or local staff) to support the communication and collaboration that surrounds the analytic steps. The reality is that many agencies will need to continue to work to develop the data, skills, and methods for a systemic pedestrian safety process. This work will likely require strong inter- jurisdictional collaboration, particularly for processes led by state DOTs. For example, different agencies may manage roadway inventories according to ownership, and many of the data types needed for a robust systemic pedestrian safety analysis may be lacking or be in the purview of others. The quality and completeness of pedestrian facilities—and the rate at which improve- ments are made—vary largely by community, and some agencies may fail to document in a timely manner when changes are made. Establishing processes both at the state and at the local level for project documentation and inventories will benefit many aspects of safety and system management. Another key consideration is whether an agency has in place a sound strategy to collect pedes- trian counts at representative locations and develop accurate volume estimates for use in risk analy- sis as described in Step 3. Traffic volume data improvements may also be needed. For example, some localities collect traffic volume data only on arterial streets, making it difficult to account for the relationship between traffic volume and pedestrian crashes across the entire network. An additional limitation is that states typically standardize crash-reporting elements that may omit important crash type information when pedestrians are involved. State agencies com- pile crash data statewide, but the quality and availability of complete and accurate data depend on timely and accurate reporting from local law enforcement agencies. In most states, police- reported crash data are rarely linked to medical data. Linking these data could further enhance analyses to understand risks associated with pedestrian injury severity. The preceding types of challenges are unlikely to become less pronounced over time (although there is a potential for improving knowledge regarding the use of surrogate risk measures), and many of these issues are relevant to prioritizing projects in all types of multi-modal safety programs. While the guidebook offers some ways to address or work around these challenges, additional coordination and funding may be needed to enhance the data quality and com- pleteness that underlie a truly data-driven systemic process for identifying focus crash types, C H A P T E R 1 3 Conclusion: Considerations and Limitations

Conclusion: Considerations and Limitations 75 analyzing risks, prioritizing locations, and identifying appropriate types of systemic pedestrian safety improvements. Consider whether it makes sense to begin now to collaborate to enhance the processes for acquiring the needed types of data and develop the structures, spatial linkages (ideally ones in which demographic and land use data can be aggregated), and partnerships across agencies to accomplish safety objectives. In the meantime, beginning the systemic process with existing data should prove quite infor- mative of needs for improvements to data and process, if the experiences of some of the early adopters (see case examples) are an indication. Continuing Research Needs The case examples outline four systemic or quasi-systemic approaches that state and local agencies have begun, using different levels of data, risk screening methods, and philosophical approaches toward prioritizing locations and countermeasures. However, the application of a systemic approach to pedestrian safety is still in its infancy, and it will be important to monitor the success of these different types of applications of the process as these efforts mature through the later steps of implementation and evaluation. Follow-up research on this guidance and process is important. Specifically, there is a need to conduct additional implementation assessment to determine which types of systemic methods are adopted, what the continuing barriers to adoption are, and which processes work best for agencies. A data-driven process and use of reliable safety performance metrics are desirable and thought to be most effective for spending safety funds wisely. But questions remain on whether there is a point of diminishing return, and if it is possible to achieve similar safety results taking a more pragmatic approach based on risk principles, land use types, and sound engineering judg- ment. This may be a particular concern in smaller communities or in others in which data quality (or quantity) is less than ideal and data shortcuts or surrogate measures are not reliable alterna- tives. Chapter 8 in the technical report provides further discussion of data and research needs. Implementation Agencies that are implementing systemic processes and treatments have a role to play in advancing research, particularly around project evaluation. There is a possibility that crash reductions at systemically treated sites may be different from those expected. These differences may be based on CMFs that may have been developed using actual higher crash sites rather than predicted high crash risk sites. There is also concern about some treatments—such as signs, which are low cost and easily implemented into a systemic process—being overused, diminish- ing their overall effectiveness. Evaluation of systemic projects is ideally something that each jurisdiction implementing a systemic approach will do, but there may be a need for collabora- tion, pooled funds, or pooled data across state and local agencies to perform robust evaluations. Such collaborations could enhance all types of safety programs and not only systemic programs. As more studies are conducted, there may also be a need to consider how factors that increase the severity of a crash, in addition to the likelihood of a crash, can be measured and best be incor- porated into systemic analyses. For example, how can travel speeds be measured in meaningful ways to assess pedestrian (and other road user) safety risk across the network or at different times, and how can such measures be incorporated into analyses to identify and prioritize risks by location? These and other issues provide fertile grounds for continuing research around systemic pedes- trian safety practices and outcomes that could enhance future practices.

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TRB's National Cooperative Highway Research Program (NCHRP) Research Report 893: Systemic Pedestrian Safety Analysis provides a safety analysis method that can be used to proactively identify sites for potential safety improvements based on specific risk factors for pedestrians. A systemic approach, as opposed to a “hot-spot” approach, enables transportation agencies to identify, prioritize, and select appropriate countermeasures for locations with a high risk of pedestrian-related crashes, even when crash occurrence data are sparse. The guidebook also provides important insights for the improvement of data collection and data management to better support systemic safety analyses.

The Contractor's Final Technical Report and a PowerPoint presentation summarizing the project accompany the report.

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