The size, geometry, and weight of farm equipment known as implements of husbandry (IoH) have increased and changed significantly to meet the needs of the modern agricultural industry. While intended primarily for use on the farm or in the field, frequently IoH travel on roads and bridges. Through a review of the history of bridge design vehicles as well as the evolution of truck size and weight legislation, it is clear that the growth of IoH has far out-paced legal vehicles. Bridges are designed based on the AASHTO live loads that are different from IoH. Therefore, research is needed to provide guidance to help bridge owners and engineers load rate bridges for IoH in order to ensure public safety and preserve bridges.
The objectives of this research were to (1) propose new implements of husbandry (IoH) load rating provisions for the AASHTO Manual for Bridge Evaluation (load factor rating “LFR” and load and resistance factor rating “LRFR”) and related revisions to the AASHTO LRFD Bridge Design Specifications; and (2) develop a set of protocols to evaluate IoH with various configurations for load rating and overload permits.