Contents of this publication may be copied provided credit is given to Public Roads and the authors. The main factor contributing to a bridge being classified as structurally deficient is a low load rating. A deficient bridge is not necessarily unsafe. That is, not every structurally deficient bridge needs to be replaced. Therefore, the proper evaluation of each bridge s load-carrying capability is essential.
Theoretical calculations tend to be very conservative, underestimating the capacity of a structure.
The only way to determine the actual capacity is to perform a load test on the bridge. This type of test is time-consuming and expensive. As a result, very few load tests are conducted, and this lack of actual testing may lead to an inaccurate count of structurally deficient bridges. The testing of these new technologies was conducted this summer in cooperation with the Alaska Department of Transportation and Public Facilities in Juneau, Alaska. These prototypes were developed under the FHWA Research and Development Program in Nondestructive Evaluation.