With increased traffic, multi-lane highways, and complex highway interchanges, highway signs play an important role in the safe operation of the nation’s transportation network. In the past, it was common to see a single large sign supported by a truss structure. In order to improve highway safety and operations, both static signs and dynamic message sign (DMS) must be used to communicate more frequently with drivers. These signs are typically larger and much heavier than the typical highway signs used in the past.
Given that wind is the main load that affects these structures during their lifetime, accurate calculation of the wind loads is essential. The existing specification needs to be updated to incorporate more current and accurate information on how the wind drag coefficient varies with (1) sign geometrical parameters (e.g., sign aspect ratio, ground clearance, and sign thickness), (2) shape of signs, and (3) type of supporting structures (e.g., signs are attached to a bridge superstructure vs. an overhead sign truss).
The objective of this research is to propose revisions to the wind drag coefficients in the AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals (LRFDLTS-1). At a minimum, the research shall develop a methodology and design examples to calculate wind drag coefficients for signs and supporting structure members that are included in the LRFDLTS-1.
Accomplishment of the project objective will require at least the following 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 contract 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.
Task 1. Conduct a literature review of relevant domestic and international research with consideration of the latest developments in accounting for wind drag coefficients and wind loads on highway signs and support structures. The review shall include research conducted through the NCHRP; FHWA; and other national, state, industry, and pooled-fund sponsored research.
Task 2. Synthesize the literature review to identify the knowledge gaps in calculation of wind drag coefficient for highway signs and support structures. Discuss the data required for the wind load calculation of highway signs and support structures. These gaps should be addressed in the final product as budget permits or in the recommended future research.
Task 3. Propose a methodology and a testing program, to be executed in Phase II, to achieve the project objective. At a minimum, the methodology shall include all the parameters that affect drag coefficient calculations for different highway signs including DMS and the unshielded and shielded members of support structures.
Task 4. Identify areas of the LRFDLTS-1 that will be revised and propose design examples using signs and support structures from DOTs inventories to illustrate the application of the new proposed revisions versus the current specifications.
Task 5. Prepare Interim Report No. 1 that documents the results of Tasks 1 through 4 and provides an updated work plan for the remainder of the project. This report is due no later than 4 months after the contract award. The updated plan must describe the process and rationale for the work proposed for Phases II and III.
Note: Following a 1-month review of Interim Report No. 1 by the NCHRP, the research team will be required to meet with the project panel to discuss the interim report. Work on Phases II and III of the project will not begin until authorized by the NCHRP. Phase I shall be limited to $35,000.
PHASE II—Plan Execution
Task 6. Develop the proposed methodology and conduct the testing program according to the approved Interim Report No.1.
Task 7. Develop the draft proposed AASHTO revisions, design examples, and the ballot item to submit with the proposed revisions to the AASHTO Committee on Bridges and Structures based on the research results and according to the approved Interim Report No.1.
Task 8. Prepare Interim Report No. 2 that documents the results of Tasks 6 and 7 and provides an updated work plan for the remainder of the project. This report is due no later than 15 months after approval of Phase I. The updated plan must describe the work proposed for Phase III
Note: Following a 1-month review of Interim Report No. 2 by the NCHRP, the research team will be required to meet in person with the project panel to discuss the interim report. Work on Phase III of the project will not begin until authorized by the NCHRP. Phase II shall be limited to $215,000.
PHASE III—Final Products
Task 9. Prepare final deliverables including: (1) the proposed AASHTO revisions, design examples, and ballot item that reflect consideration of the panel’s review comments; (2) a final report that documents the entire research effort; and (3) a stand-alone technical memorandum titled “Implementation of Research Findings and Products.” See Special Note D for additional information.
Note: Phase III shall be limited to $50,000. Following receipt of the draft final report, the remaining 3 months shall be for NCHRP review and comment and for research agency preparation of the revised final report.
A. During the research, the research team should anticipate making presentations to appropriate technical committees at two annual meetings of the AASHTO Committee on Bridges and Structures.
B. To ensure that data produced under this project are accessible, a data archiving and sharing plan shall be prepared by the agency performing the research. The plan must be submitted with Task 5 and shall include a description of expected activities, schedules, limitations, milestones, and required resources. Researchers should describe briefly the expected schedule for data production and archiving in the NCHRP permanent repository, the format of the final dataset, the documentation to be provided, and whether or not any analytic tools and/or results also will be provided. The plan must include a description of actions planned to ensure quality. Moreover, the plan must specify the resources required to archive and distribute the data expected to be obtained in the course of performing the research. In general, public release of data will not occur before full review and approval by the NCHRP project panel.
The data archiving and sharing plan must include the following sections:
C. Proposals should include a task-by-task breakdown of labor hours for each staff member as shown in Figure 4 in the brochure, "Information and Instructions for Preparing Proposals" (http://onlinepubs.trb.org/onlinepubs/crp/docs/ProposalPrep.pdf). 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.
D. The NCHRP is a practical, applied research program that produces implementable products addressing problems faced by transportation practitioners and managers. The benefits of NCHRP research are realized only when the results are implemented in state DOTs and other agencies. Implementation of the research product must be considered throughout the process, from problem statement development to research contract and beyond completion of the research. Item 4(c), "Anticipated Research Results," must include the following: (a) the "product" expected from the research, (b) the audience or "market" for this product, (c) a realistic assessment of impediments to successful implementation, and (d) the institutions and individuals who might take leadership in deploying the research product. The project panel will develop and maintain an implementation plan throughout the life of the project. 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_ActiveImlementation.pdf.
E. Item 5 in the proposal, "Qualifications of the Research Team," must include a section labeled "Disclosure." Information relevant to the NCHRP's need to ensure objectivity and to be aware of possible sources of significant financial or organizational conflict of interest in conducting the research must be presented in this section of the proposal. For example, under certain conditions, ownership of the proposing agency, other organizational relationships, or proprietary rights and interests could be perceived as jeopardizing an objective approach to the research effort, and proposers are asked to disclose any such circumstances and to explain how they will be accounted for in this study. If there are no issues related to objectivity, this should be stated.
F. Proposals are evaluated by the NCHRP staff and project panels consisting of individuals collectively very knowledgeable in the problem area. Selection of an agency is made by the project panel 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) the proposer's plan for participation by Disadvantaged Business Enterprises--small firms owned and controlled by minorities or women; and (6) the adequacy of the facilities.
Note: The proposer's plan for participation by Disadvantaged Business Enterprises should be incorporated in Item 12 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 Academies of Sciences, Engineering, and Medicine. 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 Academies of Sciences, Engineering, and Medicine. 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.