To determine how best to address a known or potential safety concern, it is necessary to properly assess the factors contributing to the crashes in order to be able to then determine appropriate countermeasures that can reduce the potential risk. As the field of quantitative safety analysis has developed, many of the procedures using the results of the quantitative analyses have also evolved. The next phase in the growth of this field should support the tasks of analyzing crash data to completely understand or diagnose a particular situation and aid in selecting countermeasures. Development of a document that provides best practices and recommendations on procedures for practitioners to use will further promote use of data-driven, quantitative approaches to consideration of safety in project decisions.
With ever-increasing recognition of the need to more fully assess countermeasures from an engineering, enforcement, emergency medical service, and education perspective, the research proposes guidance for evaluating, analyzing, and diagnosing crash data and potential countermeasures. The research will develop a tool for practitioners to assess the nature of reported crashes, overrepresentation of the contributing circumstances, manner of collision and other factors necessary to determine appropriate countermeasures using more recently developed analysis and decision methods. This includes, but is not limited to, enhancements to the use of collision diagramming and analysis, analytical visualization, gathering supporting documentation and making field based assessments as a means to supplement decision-making within safety programs and projects. The research will should assess how NCHRP Report 600 (2012), Human Factors Guidelines for Road Systems, and other supporting documents related to diagnosing safety concerns are relevant and can be used to assist the practitioner in countermeasure identification and selection.
This research will be summarized and provided to the greater highway safety community, the TRB Highway Safety Performance Committee and other related TRB Committees, AASHTO Standing Committee on Highway Traffic Safety and AASHTO Highway Safety Manual Task Force for consideration and dissemination to practitioners for use with safety assessments. This research also provides a valuable supplement to work completed under NCHRP 501: Integrated Safety Management Process, the AASHTO Highway Safety Manual, AASHTO SafetyAnalyst and road safety audits. This effort is directly linked to the AASHTO SCOHTS Strategic Plan Part 6: Management: Improving Information and Decision Support Systems, and the Towards Zero Deaths: a National Strategy on Highway Safety.
The objective of this research is to assess the state of the practice, make recommendations on methods and procedures to complete diagnostic assessments of crashes at the project and program level, and to show appropriate cases studies to complete this activity.
It is expected that the research will include the following tasks.
Task 1. Review related data-driven best practices within the highway safety field and emerging approaches in areas such as public health and big data analytics.
Task 2. Develop information on the best approaches for:
- Data management and citation during analysis to support repeatability of the analysis, and knowledge management.
- Compliance and support of the national open data initiative to promote access to data and tools (refer to www.data.gov for more information).
- Quality control on datasets and analysis results.
- Data linkage to support diagnostics (linkage of crash, roadway, traffic operation, asset management, and other datasets).
- Selection of appropriate graphics for diagnostics and reporting. For example, appropriate graph types for representing particular information, usability from a visual perspective, accessibility requirements, and information processing (human factors).
- The use of geographical information systems (GIS) for diagnostics and reporting.
Task 3. Develop case studies that guide safety professionals through recommended analysis procedures for use with the Highway Safety Manual, design exceptions and planning assessments, etc. The case studies should highlight and demonstrate specific statistical analysis necessary to support consistency and reliability of results.
Task 4. Develop a report that describes recommended methods and procedures, as well as case studies using these procedures.