BACKGROUND

The Overhead Contact System (OCS) is a foundational component of rail transit electrification, delivering power to vehicles via a suspended system of contact and messenger wires. These wires are supported by poles, cantilevers, portals, and related infrastructure that must meet rigorous structural demands under varying environmental, mechanical, and operational conditions.

Despite the widespread use of the OCS across U.S. transit systems, there is currently no nationally adopted structural design specification, standard, or code for OCS poles and foundations. Designers currently rely on a mix of partially applicable documents, including:

• IEEE 1630-2012, IEEE Standard for Supporting Structures for Overhead Contact Systems for Transit Systems, which provides general structural support guidelines but lacks prescriptive design load definitions or serviceability criteria;
• ASCE 48, Design of Steel Transmission Pole Structures, which offers useful structural insights but is not tailored to transit OCS systems; and
• IEEE C2-2023, 2023 National Electric Safety Code(R) (NESC(R)), which is commonly referenced for load calculations but primarily developed for electric utility transmission and distribution, not for rail OCS.

This fragmented approach leads to inconsistency across transit agencies and among engineering professionals in how structural design specifications, standards, or codes are interpreted and applied. The absence of consistent standards becomes even more critical as agencies pursue system expansions, high-speed rail corridors, and unconventional OCS configurations in constrained and urban environments.

Research is needed to develop a comprehensive structural design guide for OCS poles and foundations that consolidates best practices, defines consistent load and serviceability criteria, and establishes a framework for applying U.S. structural design specifications to OCS systems.

OBJECTIVE

The objective of this research is to develop a structural design guide for OCS poles and foundations applicable across standard and nonstandard transit environments. At a minimum, the research should:

1. Define and quantify the full spectrum of loads acting on OCS structures and foundations, including mechanical, dynamic, thermal, and environmental effects;
2. Describe various OCS system arrangements, including conventional and unconventional layouts, and provide structural guidance tailored to each arrangement;
3. Develop recommended load combinations for strength and serviceability design, following principles aligned with the American Association of State Highway and Transportation Officials (AASHTO) and American Society of Civil Engineers (ASCE) specifications and codes;
4. Establish serviceability limits for OCS structures, such as operating and nonoperating deflections, vibration thresholds, and wire geometry constraints; and
5. Guidance for integrating OCS-specific loads and behaviors into existing U.S. structural standards.

RESEARCH PLAN

The TCRP is seeking proposals on how best to achieve the research objective. Proposers are expected to present a research plan 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.

Note: Proposers shall include the schedule for each task in their research plans.

PHASE I - PLANNING

Task 1. Conduct a literature review and industry survey.

• Review existing standards and technical literature related to OCS structural design (e.g., IEEE, ASCE, ACI, AASHTO, EN 50119, and so forth).
• Conduct a survey of transit agencies, engineers, and manufacturers to identify current practices, challenges, and knowledge gaps.  
• Synthesize the results of the literature review and survey to identify the knowledge gaps related to the research objective. These gaps should be addressed in the final product or the recommended future research as the budget permits.

Task 2. Propose the research plan to be executed in Phase II to achieve the research objective. At a minimum, the research plan shall include:

A. Load Characterization

• Define all relevant loads acting on OCS poles and foundations, including:
  • Vertical (e.g., dead, ice) or horizontal (e.g., wind, wire tension),
  • Longitudinal (e.g., braking/traction),
  • Dynamic (e.g., pantograph interaction, vibration), and
  • Thermal effects.
• Develop load calculation methods and sample load tables for different OCS types and environmental conditions.

B. System Arrangement Typologies

• Describe the structural implications of standard OCS types (e.g., simple catenary, single wire, rigid conductor rail, trolley bus, fixed tension, auto tension, and so forth).
• Describe unconventional setups (e.g., building attachments, bridge/tunnel supports, temporary supports, and so forth).

C. Load Combination and Development of Limit States

• Recommend load combinations for strength and serviceability.
• Identify critical limit states and acceptable performance thresholds (e.g., pole deflection, wire uplift, foundation movement).

D. Structural Design Guide Outline

• Develop an annotated outline of the proposed guide. 

Task 3. Prepare the Interim Report.

• Document Tasks 1 and 2.
• Provide an updated and refined work plan for the remainder of the research. The updated plan must describe the process and rationale for the work proposed for Phase II.

Note: Following a 1-month review of Interim Report No. 1 by the TCRP, the research team will meet with the project panel to discuss the Interim Report. Work on Phase II of the project will not begin until authorized by the TCRP.

PHASE II - GUIDE DEVELOPMENT

Task 4. Develop the Structural Design Guide. 

• Develop the Structural Design Guide according to the approved Interim Report. The Structural Design Guide shall include:
  • Clearly defined load categories and standardized calculation methods,
  • Design flowcharts and examples,
  • Structural details and performance benchmarks,
  • References to applicable codes and standards, and
  • Installation guidance and standard details and diagrams.

Task 5. Submit the final deliverables, including:

1. A final report documenting the entire research effort,
2. The Structural Design Guide for OCS poles and foundations,
3. A presentation slide deck summarizing key research findings for transit agencies and design professionals to use, and
4. A technical memorandum titled “Implementation of Research Findings and Products” (see Special Note J) for agencies and code authorities to adopt the guide or incorporate into future code editions. The technical memo should detail how OCS-specific loads and behaviors can be incorporated into current AASHTO and/or ASCE codes and include proposed language for consideration as updates.

Note: Following receipt of the draft final deliverables, the remaining 3 months shall be for TCRP review and comment and for research agency preparation of the final deliverables.

SPECIAL NOTES

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

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 IV 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 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. 

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 here. 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 TCRP 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. 

G. 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.

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 Subawardees 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 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.

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.

K. 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.

L. 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.