Excuse me for it is difficult for me to input Chinese in office.
1. Judging by the picture, there should be only one truck on the bridge at the time of accident. Therefore, 160 tons on the bridge brought it down.
2. Judging by the picture, the bridge have space for about 10 trucks if you want.
3. Therefore, 10 trucks at 46 ton rating will be 460 tons. There are about 4 supports and each one should be able to stand for 120 tons or so. Or the bridge surface between two supports should be able to deal with 120 tons or so.
4. There should be enough safety redundancy for public work. 5:1 might be a good ratio and more preferable 10:1. Therefore, each section should be able to deal with at least 600 tons or so.
5. Now 160 tons in one section brought the bridge down. And brought all sections of the bridge down. Now you tell me how they rated the bridge to be 46 tons max per vehicle.
