Load effects caused by permit and illegally overloaded vehicles

Many existing bridges in the US have signs of stru ctural deterioration, such as fatigue cracks, corrosion of the structural steel elements and rein forcing bars. Thus, they are no longer able to carr y the load they were originally designed for. Deteriorati on and failure of existing bridges can be prevented by providing the adequate safety margin in the design. This requires the knowledge of the actual live loa d. The illegally overweight vehicles create significan t damage to the roads and shorten the bridge servic e life. The control of truck traffic violating the pe rmit requirements, as well as, evaluation of the ha rmful effect caused by these vehicles is a complex issue. For the recent years, a considerable amount of wei ghin-motion(WIM) records has been collected by FHWA a nd most of the State DOTs. The database of permits regularly issued by State DOTs became avail able. These data used as a major source for analysi s of the permit and illegal live load statistical par ameters. A preliminary study of the WIM data indica tes that live loads have changed with regard to traffic volume over the years, mix, and weight.