关键词: |
Bridges, Speeding, Dynamic Interaction between Vehicles and Infrastructure, Entrance conditions, Field test program, Bridge loads, Speed limits, Impact factor, Iowa Department of Transportation (Iowa DOT) |
摘要: |
The dynamic interaction of vehicles and bridges results in live loads being induced into bridges that are greater than the vehicle’s static weight. Consideration of this phenomena has been included in the American Association of State Highway Transportation Official (AASHTO) Bridge Design Specifications for many years. While the specifications have been modified over the years, questions remain about how much of an effect dynamic interaction plays. In recognition of this interaction, the Iowa Department of Transportation (DOT) currently requires that, in some instances, permitted trucks slow to five miles per hour and span the roadway centerline when crossing a bridge. Such a slowing is consistent with current specifications, which indicate that a lower dynamic impact factor may then be used for permitted vehicles. The positive effect of this is that larger loads may be allowed to cross Iowa’s bridges. However, this practice has other negative consequences. For example, the reduction in speed increases the potential for crashes, uses additional fuel, and, in some cases, may be downright impractical for bridges with high traffic volumes. In addition, the reduction in speed can have an impact on the orderly flow of traffic. |