AbstractsTransportation

"Specifications for highway bridges have been modified considerably during the past 15 years. The principal modifications have been the result of the continuous development of motor traffic. The principal changes made have been with reference to live load, impact, and allowable unit stresses. The live load has been changed to conform with the increased weight of modern motor traffic; impact has been included to provide for the effect of heavy fast-moving trucks; and the change in unit stresses has resulted by agreement of engineers. The following specifications, which will be used herein, are practically excerpts from "Specifications for Highway Bridges," issued by the American Association of State Highway Officials" – Introduction, Chapter 1, General Specifications for Designing, page 1.