Proposed New AASHTO Load Rating Provisions for Implements of Husbandry

NCHRP Research Report 951: AASHTO Load Rating Provisions for Implements of Husbandry presents bridge load rating procedures for implements of husbandry (IoH). The procedures are presented as a proposed AASHTO manual, a set of protocols, and examples of bridge load ratings for IoH. Comprehensive weigh-in-motion data collection and analysis were performed to develop the recommended live load factors.  Various bridge spans and vehicle configurations were analyzed in order to develop the new live load distribution factors. This report will be of immediate interest to bridge engineers responsible for bridge rating and ensuring public safety while allowing IoH to safely cross bridges. The size, geometry, and weight of farm equipment known as implements of husbandry (IoH) have increased and changed significantly to meet the needs of the modern agricultural industry. While intended primarily for use on the farm or in the field, IoH frequently travel on roads and bridges. A review of the history of bridge design vehicles, and the evolution of truck size and weight legislation clearly show that the growth of IoH has exceeded legal vehicles.  Bridges are designed based on the AASHTO live loads that are different from IoH. Therefore, research was needed to provide guidance to help bridge owners and engineers load rate bridges for IoH in order to both ensure public safety and preserve bridges. Research was performed under NCHRP Project 12-110 by E&T Consulting Engineers to (1) propose new implements of husbandry (IoH) load rating provisions for the AASHTO Manual for Bridge Evaluation (load factor rating “LFR” and load and resistance factor rating “LRFR”) and related revisions to the AASHTO LRFD Bridge Design Specifications; and (2) develop a set of protocols to evaluate IoH with various configurations for load rating and overload permits.


  • English


  • Status: Completed
  • Funding: $566864
  • Contract Numbers:

    Project 12-110

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway & Transportation Officials (AASHTO)

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Dekelbab, Waseem

  • Performing Organizations:

    E&T Consulting Engineers

    Chicago, IL  United States 
  • Principal Investigators:

    Fu, Gongkang

  • Start Date: 20161021
  • Expected Completion Date: 20191020
  • Actual Completion Date: 0
  • Source Data: RiP Project 40206

Subject/Index Terms

Filing Info

  • Accession Number: 01572393
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 12-110
  • Files: TRB, RiP
  • Created Date: Aug 7 2015 1:01AM