The development of natural gas resources in the Marcellus Shale formation has progressed rapidly in the last several years, particularly in the Commonwealth of Pennsylvania. These activities require many heavy truck trips for equipment and materials, which can damage state and local roads that were not designed for high volumes of heavy truck traffic. For state transportation agencies, one measure of costs of shale gas development is the potential degradation of roadways resulting from shale gas development. This technical note provides a first-order estimate of roadway consumptive use costs of additional heavy truck traffic on Pennsylvania statemaintained roadways from Marcellus Shale natural gas development in 2011, estimated at about 13,000−23,000 per well for all state roadway types, or 5,000−10,000 per well if state roads with the lowest traffic volumes are excluded. This initial estimate of costs is based on data on the distribution of well activity and roadway type in Pennsylvania, estimates for the number of heavy truck trips to construct and operate a single well, the corresponding equivalent single-axle loadings, and estimates of roadway life and reconstruction costs by roadway maintenance class in Pennsylvania.</p