BACKGROUND
The applicability of the 85th percentile speed for determining posted speed limits is a complex and controversial issue of concern to state departments of transportation (DOTs). The 85th percentile is the speed at or below which 85 percent of free-flowing traffic travels. It is sometimes used to provide an indication of the free-flow operating speed on the roadway for determining traffic control device applications. It has been used for decades as the basis for setting speed limits.
In recent years, calls have been made to eliminate the 85th percentile speed as the basis for setting speed limits, especially in urban areas. Proponents of the 85th percentile speed argue that (1) it is a good measure of the speed at which drivers feel safe and comfortable on a given road; (2) it is a relevant data point that can indicate whether other modifications or speed management strategies might be needed to achieve compliance or some level of a self-enforcing road design; (3) and setting speed limits at or near the 85th percentile speed can reduce speed variance and improve safety. Conversely, critics argue that (1) the 85th percentile speed is not a reliable measure of safe driving; (2) it can be influenced by many factors, such as traffic volume, road conditions, and drivers’ perception of law enforcement activity; and (3) setting speed limits at or near the 85th percentile speed can encourage drivers to travel at higher speeds. Therefore, critics argue that the 85th percentile speed should be removed as a factor and that the Safe System approach should be required instead.
Recent research and reasoning for moving away from the 85th percentile speed on urban arterials and residential streets do not address speed limits on freeways, expressways, and rural highways. Therefore, research is needed to examine the applicability of the 85th percentile speed for setting speed limits on freeways, expressways, or rural highways.
OBJECTIVES
The objectives of this project are to (1) examine the applicability of the 85th percentile speed as a factor in setting speed limits on freeways, expressways, and rural highways and (2) prepare a guide for state DOTs and other agencies with the authority to set speed limits on freeways, expressways, and rural highways that includes, at a minimum, implementation considerations, an application framework, and outreach materials for communication with policymakers.
RESEARCH PLAN
The NCHRP is seeking the insights of proposers on how best to achieve the research objectives. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must represent the proposers’ current thinking described in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach in meeting the research objectives. The research plan should not include surveys.
The work proposed must be divided into tasks and/or phases. Proposers must describe the work proposed in each phase and task in detail. The research plan should build in appropriate checkpoints with the NCHRP project panel, including, at a minimum, (1) a kick-off teleconference meeting to be held within 1 month of the contract’s execution date and (2) one in-person interim deliverable review meeting. An annotated outline for the guide shall be included with the interim report. The draft guide is due no later than 6 months before the contract end date.
The research plan shall include a workshop with at least 15 diverse representatives of state DOTs to (1) demonstrate the draft guide and (2) collect and use participant feedback to revise and finalize the guide. At a minimum, workshop preparations shall include issuing invitations to NCHRP-approved participants and preparing a final list of attendees; providing travel support for workshop attendees; providing catering services for all participants, including panel members; preparing name tags for all participants; and preparing workshop materials, including PowerPoint presentations and any handouts.
Note: The costs for the workshop, including invitational travel for at least 15 attendees (not including members of the research team), should be included in the detailed budget for the research. For the purpose of estimating these costs, assume that the workshop will be held at a TRB facility (Keck Center in Washington, DC, or the Beckman Center in Irvine, CA). NCHRP will cover costs associated with NCHRP panel member travel. Catering services for all participants, including panel members, should be included in the detailed budget for the research.
The final deliverables will include at a minimum:
1. A guide.
2. A final report that includes:
- a summary of the research findings;
- documentation of the entire project;
- an executive summary; and
- recommendations of needs and priorities for additional related research.
3. A PowerPoint presentation with presenter’s notes summarizing the research findings.
4. A stand-alone technical memorandum titled “Implementation of Research Findings and Products” (see Special Note J for additional information).
Note: Following receipt of the draft final deliverables, the remaining 3 months shall be for NCHRP review and comment and for research agency preparation of the final deliverables.
SPECIAL NOTES
A. The Information and Instructions for Preparing Proposals for the Transportation Research Board’s Cooperative Research Programs were revised in May 2023. Please take note of the new and revised text which is highlighted in yellow.
B. Proposals must be submitted as a single PDF file with a maximum file size of 10 MB. The PDF must be formatted for standard 8 ½” X 11” paper, and the entire proposal must not exceed 60 pages (according to the page count displayed in the PDF). Proposals that do not meet these requirements will be rejected. For other requirements, refer to chapter V of the instructions.
C. The Information and Instructions for Preparing Proposals for the Transportation Research Board’s Cooperative Research Programs have been modified to include a revised policy and instructions for disclosing Investigator Conflict of Interest. For more information, refer to chapter IV of the instructions. A detailed definition and examples can be found in the CRP Conflict of Interest Policy for Contractors. The proposer recommended by the project panel will be required to submit an Investigator Conflict of Interest and Disclosure Form as a prerequisite for contract negotiations.
D. Proposals will be rejected if any of the proposed research team members work for organizations represented on the project panel. The panel roster for this project can be found at https://www.mytrb.org/OnlineDirectory/Committee/Details/7079. Proposers may not contact panel members directly; this roster is provided solely for the purpose of avoiding potential conflicts of interest.
E. Proprietary Products - If any proprietary products are to be used or tested in the project, please refer to Item 6 in the Information and Instructions for Preparing Proposals.
F. Proposals are evaluated by the NCHRP staff and project panels consisting of individuals collectively knowledgeable in the problem area. The project panel will recommend their first choice proposal considering the following factors: (1) the proposer's demonstrated understanding of the problem; (2) the merit of the proposed research approach and experiment design; (3) the experience, qualifications, and objectivity of the research team in the same or closely related problem area; (4) the plan for ensuring application of results; (5) how the proposer approaches inclusion and diversity in the composition of their team and research approach, including participation by certified Disadvantaged Business Enterprises; and, if relevant, (6) the adequacy of the facilities. A recommendation by the project panel is not a guarantee of a contract. The National Academy of Sciences (NAS - the contracting authority for the National Academies of Sciences, Engineering, and Medicine) will conduct an internal due diligence review and risk assessment of the panel’s recommended proposal before contract negotiations continue.
Note: The proposer's approach to inclusion and diversity as well as participation by Disadvantaged Business Enterprises should be incorporated in Item 11 of the proposal.
G. Copyrights - All data, written materials, computer software, graphic and photographic images, and other information prepared under the contract and the copyrights therein shall be owned by the National Academy of Sciences. The contractor and subcontractors will be able to publish this material for non-commercial purposes, for internal use, or to further academic research or studies with permission from TRB Cooperative Research Programs. The contractor and subcontractors will not be allowed to sell the project material without prior approval by the National Academy of Sciences. By signing a contract with the National Academy of Sciences, contractors accept legal responsibility for any copyright infringement that may exist in work done for TRB. Contractors are therefore responsible for obtaining all necessary permissions for use of copyrighted material in TRB's Cooperative Research Programs publications. For guidance on TRB's policies on using copyrighted material please consult Section 5.4, "Use of Copyrighted Material," in the Procedural Manual for Contractors.
H. The text of the final deliverable is expected to be publication ready when it is submitted. It is strongly recommended that the research team include the expertise of a technical editor as early in the project timeline as possible. See Appendix F of the Procedural Manual for Contractors Conducting Research in the Transportation Research Board’s Cooperative Research Program for technical editing standards expected in final deliverables.
I. Proposals should include a task-by-task breakdown of labor hours for each staff member as shown in Figure 4 in the Information and Instructions for Preparing Proposals. Proposals also should include a breakdown of all costs (e.g., wages, indirect costs, travel, materials, and total) for each task using Figures 5 and 6 in the brochure. Please note that TRB Cooperative Research Program subawards (selected proposers are considered subawards to the National Academy of Sciences, the parent organization of TRB) must comply with 2 CFR 200 – Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards. These requirements include a provision that proposers without a "federally" Negotiated Indirect Costs Rate Agreement (NICRA) shall be subject to a maximum allowable indirect rate of 10% of Modified Total Direct Costs. Modified Total Direct Costs include all salaries and wages, applicable fringe benefits, materials and supplies, services, travel, and up to the first $25,000 of each lower tier subaward and subcontract. Modified Total Direct Costs exclude equipment, capital expenditures, charges for patient care, rental costs, tuition remission, scholarships and fellowships, participant support costs and the portion of each lower tier subaward and subcontract in excess of $25,000.
J. The required technical memorandum titled “Implementation of Research Findings and Products” should (a) provide recommendations on how to best put the research findings/products into practice; (b) identify possible institutions that might take leadership in applying the research findings/products; (c) identify issues affecting potential implementation of the findings/products and recommend possible actions to address these issues; and (d) recommend methods of identifying and measuring the impacts associated with implementation of the findings/products. Implementation of these recommendations is not part of the research project and, if warranted, details of these actions will be developed and implemented in future efforts.
The research team will be expected to provide input to an implementation team consisting of panel members, AASHTO committee members, the NCHRP Implementation Coordinator, and others in order to meet the goals of NCHRP Active Implementation: Moving Research into Practice, available at http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP_ActiveImplementation.pdf
K. If the team proposes a Principal Investigator who is not an employee of the Prime Contractor, or if the Prime Contractor is proposed to conduct less than 50% of the total effort (by time or budget), then section five of the proposal should include: (1) a justification of why this approach is appropriate, and (2) a description of how the Prime Contractor will ensure adequate communication and coordination with their Subcontractors throughout the project.
L. All budget information should be suitable for printing on 8½″ x 11″ paper. If a budget page cannot fit on a single 8½″ x 11″ page, it should be split over multiple pages. Proposers must use the Excel templates provided in the Information and Instructions for Preparing Proposals for the Transportation Research Board’s Cooperative Research Programs.
M. The National Academies have an ethical and legal obligation to provide proper attribution whenever material from other sources is included in its reports, online postings, and other publications and products. TRB will review all Cooperative Research Programs draft final deliverables using the software iThenticate for potential plagiarism. If plagiarized text appears in the draft final deliverable, the research team will be required to make revisions and the opportunity to submit future proposals may be affected.
