The North Carolina Department of Transportation (NCDOT) is the largest state DOT in the United States, responsible for over 77,000 miles of state roads and bridges. As a result, NCDOT has one of the nation's most comprehensive transportation improvement plans. For the period 1996-2004 the NCDOT has scheduled over 2,500 highway and bridge improvement projects. North Carolina also has an abundance of environmentally sensitive wetlands along its expansive coast and coastal plains area. Until recently, the NCDOT Environmental Permits and Wetland Mitigation Unit had no systematic way of predicting the impact of these highway improvements on wetlands. In 1995, however, the NCDOT in conjunction with the Institute for Transportation Research and Education (ITRE) conducted a study utilising Geographic Information Systems (GIS) to estimate wetland impacts caused by highway construction projects programmed for 1996-2004 in order to forecast wetland mitigation needs. Wetland impacts were estimated by measuring the overlap of highway improvement projects with wetland areas using two primary data sources: the 1996-2002 Transportation Improvement Program (TIP) and the National Wetland Inventory (NWI). Using geometric and coincidence modelling techniques afforded by GIS, wetland impacts were identified, quantified, summarised, and reported by amount, type, location, and timing.
Abstract