The TRB Testing and Evaluation of Transportation Structures committee consists of members from infrastructure owners, practicing engineers, nondestructive testing providers, and researchers. This committee is concerned with condition assessment and evaluation of the performance of transportation structures. The committee addresses the use of testing, monitoring, and nondestructive evaluation methods to assess the load-carrying capacity of structures, detect and quantify defects, and assess condition. The primary focus of the committee has been the transfer of knowledge to promote practical application of research for evaluation of structures for effective asset management. To encourage rapid adoption of the latest technologies and methods, the committee has been pursuing products that demonstrate the successful application of technologies and methods for the condition assessment and performance evaluation of transportation structures. This ECircular is a product of these efforts. Load testing has been one of the recognized methods to evaluate and load rate bridge structures. While advanced calculation methods are available to determine the ultimate capacity of existing structures, timely and accurate in-service data needed for model input and service life prediction is not always forthcoming. 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 E-Circular provides significant updates to the existing documents to reflect the current state of the practice on bridge load testing, and will cover 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.