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The National Academies

TCRP D-27 [Anticipated]

Establishing Design Loads, Load Combinations, and Structural Design Methodology for OCS Poles and Foundations

  Project Data
Funds: 280000
Staff Responsibility: Mariela Garcia-Colberg
Comments: In development
Fiscal Year: 2025

This project has been tentatively selected and a project statement (request for proposals) is expected to be available on this website. The problem statement below will be the starting point for a panel of experts to develop the project statement.

The Overhead Contact System (OCS) is a key method for powering rail transit, especially in urban and non-exclusive corridors like light rail and streetcars. It consists of powered electrical wires suspended from poles spaced 100 to 150 feet apart. In the U.S., there is no standardized code for the structural design of these poles and foundations. While IEEE Std 1630-2012 and ASCE 48 provide some guidance, they do not fully address OCS-specific requirements like loads and serviceability criteria. The NCES C2-2023 standard is often used for load calculations but is geared toward transmission lines, not OCS.


There is a need for comprehensive guidelines that cover the structural design of OCS poles, including load definitions, load combinations, design philosophy, and requirements for poles that carry additional structures like street signs or traffic signals.


The research aims to:

  1. Define the loads on OCS wires and poles.
  2. Describe various OCS arrangements and provide guidance for unconventional setups.
  3. Define load combinations for strength and serviceability design.
  4. Establish serviceability limits for OCS structures.
  5. Recommend an appropriate structural design code for poles and foundations (AASHTO, ACI, ASCE, etc.), with guidance on integrating OCS load combinations into the code.

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