随着交通运输量大幅度增长,行车密度及车辆载重越来越大,现有道路中部分中小桥梁或由于当初设计标准低,经过一段时间的交通发展,荷载标准或桥上、桥下的净空不能满足新交通的需要,或结构陈旧老化、破损影响到它原有设计能力而危及运行的,严重影响了交通运输的发展。 With the substantial increase in traffic volume, traffic density and vehicle load are increasing. Some of the existing small and medium-sized bridges in roads or due to the original low design standards, after a period of traffic development, load standards or bridge, bridge clearance Failure to meet the needs of new transportation, aging of structures, or damage to their original design capabilities endangers operation, seriously affecting the development of transportation.