Each year, roadway departure crashes in the United States result in serious injuries and fatalities. Between 2012-2014, the average number of fatalities per year resulting from roadway departure crashes was 18,355. Of that number, 7,349 fatalities resulted from impacts with fixed objects such as trees, shrubbery, utility poles, luminaire poles, sign supports, and traffic signals—all classified as the most harmful events. (Source: Fatal Analysis Reporting System, NHTSA).
Current guidance directs transportation agencies to remove or avoid placing fixed objects within regions close to the traveled way. However, agencies must often consider numerous competing interests. For example, roadside trees are noted to provide environmental and aesthetic benefits. In addition, discussion of tree removal can become a contentious issue for the general public as well as specific interest groups. Overhead utilities located along the right-of-way provide essential services to residential and commercial customers, but relocation of those utilities is often costly.
As transportation agencies continue to expand the use of data-driven decision-making processes and performance-based design decisions, the need to quantitatively evaluate the safety risks posed by fixed objects located near the traveled way as well as the benefits of implementing various safety treatments within the clear zone is necessary. With recent concepts such as context-sensitive solutions, complete streets, and practical design evolving into more mainstream practices, there are many factors that must be considered and balanced in the development of the roadside environment. Transportation practitioners need a risk-based, technical approach to help mitigate fatal and serious injury crashes with fixed objects with in the right-of-way. This alternative approach will allow engineers to quantitatively and impartially balance safety with other factors as well as better communicate to decision makers and the public the safety risks posed by fixed objects placed in close proximity to the roadway.
Results of this research will enable transportation agencies to set and evaluate their level of safety risk and use quantitative information in the decision-making process. This is consistent with the approach for other guidance being developed for the next version of the AASHTO Roadside Design Guide (RDG).
The objectives of this research are to develop an evaluation methodology and guidance for use by the transportation engineering practitioner to quantify the relative risk of collisions with roadside fixed objects. The research results are intended for inclusion as a new chapter or supplement in a future edition of the Roadside Design Guide.
The results should address a broad range of roadside safety issues considering but not limited to: traffic volume; speed; crash severity; urban and rural land use; horizontal curvature; roadway geometrics; fixed-object type, size, and offset; and fixed-object density. The effectiveness of various mitigation strategies in lieu of removal or relocation should also be considered or evaluated.
A kick-off teleconference of the research team and NCHRP shall be scheduled within 1 month of the contract’s execution. The work plan should be divided into two phases, with each task described in detail. Phase 1 will produce an interim report and consist of, at a minimum, preliminary evaluation methodology developed and an outline or framework of the proposed guidance for inclusion in the Roadside Design Guide, and will identify completed, planned and anticipated pilot studies or verification analysis to validate the methodology. The interim report will describe the work completed in the Phase 1 tasks and provide an updated work plan for the Phase 2 tasks to complete the project objectives.
The updated Phase 2 work plan should address the manner in which the proposer intends to use the information developed in Phase 1 to satisfy the project objective. The Phase 1 interim report and panel meeting should occur after the expenditure of no more than 40 percent of the project budget. Submission of the Phase 1 report will be followed by a face-to-face meeting with NCHRP and the project panel. No work shall be performed on Phase 2 without NCHRP approval.
At the completion of Phase 2, the final deliverables at a minimum shall include:
1. A final report documenting the entire project incorporating all other specified deliverables that also includes an executive summary and the research team’s recommendation of research needs and priorities for related research.
2. A stand-alone comprehensive compilation of materials, evaluation methodology, and guidance intended for incorporation in a format suitable as a new chapter for possible adoption in the next edition RDG.
3. An electronic or PowerPoint presentation describing the project background, objective, research method, findings, and guidelines that summarizes the project and that can be tailored for specific audiences.
4. A webinar on the results of the research and the deliverables.
5. Recommendations for the development or refinement of data-driven tools (e.g., spreadsheets, software, checklists, and/or enhancements to existing electronic tools) for application of the methodology based on the research results, including content, budget, and program requirements.
6. A stand-alone technical memorandum titled “Implementation of Research Findings and Products”.
STATUS: Research in progress.