Many Class I railroads across the United States and in Pennsylvania have been adopting a 286,000 pound GVW car as the standard maximum weight car to replace the previous 263,000 pound limit. These large freight carriers have been compelled to increase their productivity in response to competitive pressures and shipper demand. The Class I railroads interline with the short line railroads in order to deliver cars closer to the shippers' destination. Most short line railroads do not have the resources to completely evaluate or upgrade their infrastructure capacity nor do they have the personnel and capital to keep track and bridge structures as well maintained or as well documented as the Class I railroads. Many railroad structures were built in the late 1800's and early 1900's. Assessment of the economic impact on the short line railroad infrastructure is complicated by the fact that railroad structures have been built with different materials and construction techniques. Government agencies concerned with facilitating the transport of goods, and the corresponding economic impact, recognize the dilemma of short line railroads. This study is motivated by economic interests of the commonwealth to evaluate the impact of heavy rail cars on the short line railroad system. The Pennsylvania Department of Transportation (PennDOT) Bureau of Rail Freight and Waterways has undertaken this study to determine the cost of upgrading short line railroads track structure and bridges.