A proof-load test is often necessary to accurately measure the field behavior of a bridge structure before opening service. The cables are typically in two planes separated by the width of the roadway. However, numerous bridges have been built with a central plane of stays between the two opposing lanes of traffic, designed in Vietnam recently. Almost all the extradosed bridges are concrete box girders. Engineers performed proof load tests before opening the structure to evaluate its load-carrying capacity and deck deflection. This paper presents several aspects of load testing and evaluation of bridge structures under static and dynamic loads. The study reveals that the tested bridge has an elastic behavior, a high capacity, and adequate dynamic performance.