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Response-Based Load Rating of Steel Bridges

Project Information

Project ID: 
Project Status: 
Start Date: 
Monday, April 11, 2011
End Date: 
Tuesday, June 4, 2013
FHWA Program: 
FHWA Subprogram: 
TRT Terms: 
Investigation of Structure; Measurement; Inspection; Testing Equipment; Live Loads; Load Factor; Traffic Control; Infrastructure; Bridges; Steel Bridges; Load Rating
FHWA Discipline: 
Subject Area: 
Bridges and other structures

Contact Information

First Name: 
Last Name: 
(202) 493-3064
Email Address: 
Infrastructure Analysis and Construction Team
Office of Infrastructure Research and Development
Office Code: 

Project Details

Project Description: 

The project will develop a tentative technical approach identifying what, how, when, where, and for how long data need to be collected, as well as how it might be used to produce ratings. The statistical and reliability theories employed by the Load and Resistance Factor Rating (LRFR) Specifications shall be reviewed for requirements and restrictions applicable to processes or procedures for the actual collection of data when developing this plan. After the plan has been approved by the Contracting Officer Technical Representative (COTR), the contractor shall conduct market research on sensors and data gathering technologies to determine if there are commercially available systems that will collect long-term field measurements of bridge data (strains and possibly deflections) under regular highway/roadway traffic. These sensors and data collection systems shall have the capability of gathering the data without having to impede traffic with lane closures or other forms of work zone traffic control. Rating equations and possible algorithms shall be developed. The equations and algorithms shall also utilize the statistical and reliability theory employed by the LRFR Specifications to produce reliability-based load ratings. Laboratory tests will be performed for validation of the equipment for use in the field without impact to traffic. After laboratory validation of the sensors and data collection systems and tools, field measurements will be taken with actual bridge traffic; however, consideration will be given to a heavy moving test load mixed with traffic, without interruption to traffic and without lane closures. A final report will document the entire research effort, including an American Association of State Highway and Transportation Officials(AASHTO) ballot item to be presented to AASHTO T-18 for consideration and possible incorporation into the AASHTO Bridge Evaluation Manual.


The key project objective is to produce Load and Resistance Factor Rating (LRFR) procedures and tools for converting field measurements into load ratings for bridges that have calculated load ratings requiring them to be posted.