According to the National Bridge Inventory, the most common type of short-to-medium span highway bridge in the US is the reinforced concrete (RC) slab-on-steel girder bridge with RC abutments and piers, comprising approximately half of Ohio's inventory. For these bridges AASHTO currently offers a number of rating methods each of which is based solely on theoretical and design calculations. These methods are known to result in subjective/conservative ratings, not calibrated against field measurements, and hence possibly not objectively reflecting the realities and impacts of individual bridge condition as well as design details. Visual inspections provide at best qualitative and subjective information on bridge condition which is hard to incorporate into the rating process. One result of this approach is the potentially inefficient management and maintenance practices based on conservative/subjective ratings and inspection reports. In addition, there is the need to understand the true impact design and construction practices have on serviceability and safety of the bridge inventory, something which cannot be explored based on the current approaches.