Primer on Bridge Load Testing

Load testing of bridges to assess bridge performance has been in practice since at least 1891 in Switzerland. In times when engineering models were not as accurate and available as today, a critical step in the construction of a bridge was to load test prior to opening or during the opening ceremony of the bridge. Several bridges, including ones in Serbia, Switzerland, and France, collapsed during such load tests.

While advanced calculation methods are available to determine the ultimate capacity of existing structures, load testing provides a useful alternative for such cases where current calculation methods, for one reason or another, cannot provide satisfactory answers to performance questions on existing bridges.

AASHTO’s Manual for Bridge Evaluation and the 1998 Manual for Bridge Rating Through Load Testing have been generally used as a guidance to load testing. This TRB E-Circular, TR Circular E-C257: Primer on Bridge Load Testing, provides significant updates to the existing documents to reflect the current state of the practice on bridge load testing. It covers the preparation, execution, and analysis of load tests, including diagnostic and proof tests. If effectively used, these methods can extend the useful life of existing bridges in a cost-effective fashion.