Proposed Modifications to AASHTO Culvert Load Rating Specifications

The choice of load rating method may affect the transportation of goods and services over the nation’s highways by imposing load limits on routes that were previously unrestricted. For culvert load rating, engineers use the load and resistance factor rating (LRFR), load factor rating (LFR), or allowable stress rating (ASR) of highway bridges according to the AASHTO Manual for Bridge Evaluation. However, culverts respond to live loads differently than bridges as a result of surrounding soils. Moreover, the LRFR is calibrated based primarily on bridge response to gross truck weight, while culvert response should be calibrated based on a single axle or a single wheel. As a result, the current specifications may be either overly conservative or inadequate, which may lead to expensive replacements or upgrades, or premature deterioration or failure, respectively. Therefore, there is an immediate need to develop a load rating process for culvert structures to maintain an acceptable level of culvert reliability without unnecessary restrictions on commerce. The TRB National Cooperative Highway Research Program's Web-Only Document 268: Proposed Modifications to AASHTO Culvert Load Rating Specifications proposes modifications to the culvert load rating specifications in the Manual for Bridge Evaluation and revises the AASHTO LRFD Bridge Design Specifications accordingly.


  • English


  • Status: Completed
  • Funding: $500000
  • Contract Numbers:

    Project 15-54

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Performing Organizations:

    Michael Baker, Jr., Inc.

  • Principal Investigators:

    Mlynarski, Mark

  • Start Date: 20150707
  • Expected Completion Date: 20190331
  • Actual Completion Date: 20190331

Subject/Index Terms

Filing Info

  • Accession Number: 01781570
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 15-54
  • Files: TRB, RIP
  • Created Date: Sep 13 2021 3:12PM