BACKGROUND

Turn lanes, one of the Federal Highway Administration’s (FHWA’s) proven safety countermeasures for motor vehicles, are recommended to reduce the risk of collisions involving vehicles turning left across opposing through traffic and rear-end collisions. However, a preliminary analysis of 2017–2024 crash data from Washington State indicated that pedestrian-involved fatal and serious injury crashes occurred more frequently at intersections with left turn lanes, and at intersections with both right and left turn lanes, compared to intersections with no turn lanes.

This raises important questions about how turn lanes influence intersection safety for all road users:

• What effect do turn lanes have on operating speeds at the intersection and along the broader corridor?
• How do turn lanes impact the risk of fatal and serious injury crashes for vulnerable road users (VRUs)?

While turn lanes may improve network efficiency and reduce vehicle conflicts, they may diminish a traffic calming feature that has a wider effect on vehicle operating speeds. Turn lanes also may influence VRUs’ conspicuity and predictability, increasing crossing distances, and creating additional vehicle–VRU conflict points through altered temporal and spatial separation between modes. Research is needed to quantify these effects, evaluate turn lanes (including their effects on crash exposure, likelihood, and severity), and provide actionable recommendations.

OBJECTIVE 

The objective of this research is to quantify impacts of turn lanes on vehicle operating speeds and VRU fatal and serious injury crashes in urban areas. The research shall focus on the following aspects:

1. Evaluate impacts of the presence of turn lanes on:

• Operating speeds of turning vehicles at conflict points with VRUs;
• Operating speeds of vehicles along corridors; and
• Approach speeds of through vehicles adjacent to turn lanes.

2. Investigate correlations between turn lanes and VRU fatal and serious injury crashes to develop crash modification factors (CMFs) for removing turn lanes to potentially reduce VRU fatal and serious injury crashes.

Accomplishment of the project objective will require at least the following tasks.

TASKS 

Task descriptions are intended to provide a framework for conducting the research. The NCHRP is seeking the insights of proposers on how best to achieve the research objective. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and subaward time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objective.

The research shall focus on urban areas with posted speed limit of 45 mph or less. Proposers may also recommend and justify additional or alternative criteria based on their understanding of the research needs.  

PHASE I – PLANNING

Task 1. Conduct a comprehensive literature review of research. The review shall include state and local agencies; the American Association of State Highway and Transportation Officials (AASHTO), the National Association of City Transportation Officials (NACTO), and the Institute of Transportation Engineers (ITE) guidelines and standards; and published and unpublished research conducted through the NCHRP, FHWA, and other national, international, state, and pooled fund sponsored research. High-level policy documents should be considered for this task as appropriate. 

Synthesize findings from the literature review with a focus on how turn lanes affect operating speeds, and fatal and serious injury crashes involving VRUs in urban context. Incorporate documented before-and-after crash evaluations involving turn lane removal or repurposing for traffic calming treatments.

Task 2. Propose research methodology to achieve the research objective (see Special Note A). This methodology will be fully developed in Phase II and shall, at a minimum, include the following components:

• For the first aspect of the objective:
  • Elements, criteria, and scenarios to be considered and prioritized in the research;
  • A comprehensive data collection plan; and
  • A plan for assessing the impact of turn lanes on operating speeds for turning vehicles, through vehicles, and along the corridor.
• For the second aspect of the objective:
  • A revised and expanded data collection plan that builds on the first aspect and focuses on historical crash data;
  • An approach for comparing test sites and comparison sites, with and without turn lanes;
  • A plan for assessing the impact of turn lanes on fatal and serious injury crashes for VRUs; and
  • A plan to develop CMFs with a three-star or higher rating (for left-turn lanes only, right-turn lanes only, and/or combined).

Task 3. Prepare an annotated outline for the research report.

Task 4. Prepare Interim Report No.1 documenting the results of Tasks 1 through 3 and provide an updated plan for the remainder of the research no later than 4 months after subaward. The updated plan must describe the process and rationale for the work proposed for Phases II.

Note: Following a 1-month review of Interim Report No. 1 by the NCHRP, the research team will be required to meet with the NCHRP project panel in-person in Washington, DC to discuss the interim report. Work on Phase II of the project will not begin until authorized by the NCHRP. Phase I budget shall not exceed $50,000. 

PHASE II — EXECUTION AND FINAL DELIVERABLES

Task 5. Execute the methodologies outlined in Task 2 in accordance with the approved Interim Report No. 1. Provide monthly data collection updates to NCHRP, and document the effects of turn lanes on speed and the development of CMFs that meet three-star or higher criteria.

Task 6. Develop and submit a draft research report and document(s) that support the CMFs to be considered by the CMF Clearinghouse. 

Task 7. Conduct two in-person presentations of the panel-approved research results to two appropriate AASHTO committees, such as the Technical Committee on Non-motorized Transportation and Subcommittee on Local Road Safety, for comments; propose any revisions to the NCHRP panel. Finalize the draft research report after consideration of practitioners' feedback. 

Task 8. Develop a draft PowerPoint presentation with speaker notes summarizing the revised research report. The presentation slides shall specify the research objective, key findings, research products developed, and benefit or value of the research findings. 

Task 9. Prepare the final deliverables, including:

• A final research report documenting the entire research process and findings;
• Document(s) that support the CMFs to be considered by the CMF Clearinghouse; 
• A final PowerPoint presentation with speaker notes summarizing the revised research report; and 
• A technical memorandum titled “Implementation of Research Findings and Products” (see Special Note K).

Note: The research plan may include additional deliverables and panel meetings via teleconferences. 

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. At a minimum, the following items shall be incorporated into the Task 2 comprehensive data collection plan. Proposers are strongly encouraged to provide additional thoughts in the proposal to demonstrate a clear understanding of data needs and availability in support of successful research outcomes.

• Data types and metrics such as crash history, geometry, intersection type, traffic control type, turn lane type, posted speed limit, presence of pedestrian and bicycle facilities, operating conditions (e.g., annual average daily traffic (AADT), peak hour volumes, speeds, time of day), etc.;
• Data inventory that already exists by source, years, granularity, access status, data restrictions (if applicable), and gaps; agencies or vendors to be contacted, with timing (initial outreach and scheduled follow-ups);
• Data to be collected in the field, in a virtual environment, from agencies, from previous projects, or purchased from third-party providers to fill identified gaps. For each dataset, specify type, spatial/temporal resolution, fields, licensing, contacts, and target completeness;
• Study windows suitable for proposed speed and crash analysis, documenting any excluded anomalous periods;
• Minimum sampling/coverage requirements appropriate to the source;
• Quality assurance and quality control (QA/QC) strategies addressing completeness, data coverage, and cross-source consistency checks, along with standard descriptive statistics for operational data to enable consistent comparisons; and
• Data achieving and sharing plan.

B. Revisions to the Information and Instructions for Preparing Proposals for the Transportation Research Board’s Cooperative Research Programs are highlighted in yellow within that document.

C. 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 IV of the instructions.

D. 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 Subawardees. The proposer recommended by the project panel will be required to submit an Investigator Conflict of Interest and Disclosure Form as a prerequisite for subaward negotiations.

E. 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/7245. Proposers may not contact panel members directly; this roster is provided solely for the purpose of avoiding potential conflicts of interest.

F. 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.

G. 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; and, if relevant, (5) the adequacy of the facilities. A recommendation by the project panel is not a guarantee of a subaward. 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 subaward negotiations continue.

H. Copyrights - All data, written materials, computer software, graphic and photographic images, and other information prepared under the subaward and the copyrights therein shall be owned by the National Academy of Sciences. The subawardee and lower-tier subawardees 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 subawardee and lower-tier subawardees will not be allowed to sell the project material without prior approval by the National Academy of Sciences. By signing a subaward with the National Academy of Sciences, subawardees accept legal responsibility for any copyright infringement that may exist in work done for TRB. Subawardees 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 Subawardees.

I. 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 Subawardees Conducting Research in the Transportation Research Board’s Cooperative Research Program for technical editing standards expected in final deliverables.

J. 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 selected proposers are considered subawards to the National Academy of Sciences, the parent organization of TRB. TRB Cooperative Research Program subawards 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) or audited indirect rates shall be subject to a maximum allowable indirect rate of 15% of Modified Total Direct Costs (de minimis rate). Modified Total Direct Costs include all salaries and wages, applicable fringe benefits, materials and supplies, services, travel, and up to the first $50,000 of each lower-tier subaward. 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 in excess of $50,000.

K. 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

L. If the subawardee 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 subawardee will ensure adequate communication and coordination with their lower-tier subawardees throughout the project.

M. 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.

N. 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.