目前全国各地公路上交通量日益增加,重型车也日渐增多,这样就加重了桥梁的负担。简支梁木桥原设计载重能力有限,如全面进行加固,提高载重标准,很难实现;即使在个别路线上进行,人力、财力、物力也感困难。因此,有些养路单位就按照设计的载重标准,在桥两头竖起载重限制牌,禁止超过限制载重的车辆通行。这样就约束了运输潜力的发挥,阻碍了重型车辆的通行。相反有的养路单位则放任自流, At present, the traffic volume around the country is increasing day by day, and heavy-duty vehicles are increasing day by day, which adds to the burden on the bridge. The original design of simply supported beam wooden bridge has limited load capacity. If it is fully reinforced and the standard of load is increased, it will be very difficult to realize. Even on individual routes, human, financial and material resources will be difficult. Therefore, some maintenance units in accordance with the design of the load standards, erected at both ends of the bridge load limit card, prohibit the passage of vehicles over the limit load. This constrains the development of transport potential and hinders the passage of heavy vehicles. On the contrary, some road maintenance units are laissez-faire,