Study of the Impacts of Implements of Husbandry on Iowa Bridges

Project status


Start date: 01/25/10
End date: 09/30/17


Principal investigators:

Co-principal investigators:

About the research

The objectives of this study were to develop guidance for engineers on how implements of husbandry loads are resisted by traditional bridges, with a specific focus on bridges commonly found on the secondary road system; provide recommendations for accurately analyzing bridges for these loading effects; and make suggestions for the rating and posting of these bridges.

To achieve the objectives, the distribution of live load and dynamic impact effects for different types of farm vehicles on three general bridge types—steel-concrete, steel-timber, and timber-timber—were investigated through load testing and analytical modeling. The types of vehicles studied included, but were not limited to, grain wagons/grain carts, manure tank wagons, agriculture fertilizer applicators, and tractors.

Once the effects of these vehicles had been determined, a parametric study was carried out to develop live load distribution factor (LLDF) equations that account for the effect of husbandry vehicle loads. Similarly, recommendations for dynamic effects were also developed.

Finally, suggestions on the analysis, rating, and posting of bridges for husbandry implements were developed.

The third volume of the report contains six appendices that include the 19 mini-reports for field tested and analytically modeled steel-concrete, steel-timber, and timber-timber bridges, the farm implement and bridge inventories for the project, and survey responses.



Related publications:



  • Federal Highway Administration Transportation Pooled Fund
  • Iowa Department of Transportation
  • Iowa Highway Research Board