Type of traffic on the bridge

[KOKONIS36]

Basically the type of traffic on a bridge consist of 3 elements:Vehicles,Trucks and Buses.My question is:How much in percentage terms % should be the Truck traffic on average ? Is there any limit (percentage of trucks)beyond which a bridge is probably overloaded ?

 

[Qshake]

Unless you are redefining the codes or developing a specific code for use in a particular structure, codes such as AASHTO already specify the "live load" that is to be used in designing bridges. In the US, this is the HS-20 for most applications and for interstate applications many states are opting for the HS-25 (HS-20 Modified) to reflect heavier loads in shipping routes. I'm sure that the British Standard have some equivilent loading structure.

Noting that the overall weight of the vechicle and axle arrangement mentioned above is shown to be at a comfortable statistical level above most vehicles (all categories) there is no reason to evaluate cars, buses, trucks on an individual basis for normal design. However, once the bridge is designed, there is some inherent overcapacity, and the structure is rated in comparision to more realistic vehicles. Thus for individual overloaded vehicles it is important that they obtain a permit to travel across the bridges enroute to their destination. This, however, doesn't happen frequently at all for new designs and the permitting process remains as a safety check for older, well traveled structures.