Urban Transportation

Pursuant to a congressional request, GAO reviewed the use of transportation control measures (TCM) to control automobile-source emissions, focusing on: (1) TCM effectiveness in reducing pollution; and (2) whether TCM can be implemented in areas that do not have air quality standards. GAO found that: (1) although traditional TCM are projected to reduce overall emissions by only 5 percent, transportation planners believe that TCM, in conjunction with other pollution reduction programs could help localities achieve greater reductions in air pollution and meet pollution legislation requirements; (2) 56 percent of metropolitan planning organizations stated that TCM would receive strong emphasis in their transportation programs over the next 5 years; (3) market-based TCM that create financial disincentives and attempt to change travel behavior may be more effective than traditional TCM in reducing automobile and carbon monoxide emissions; (4) although the Department of Transportation and the Environmental Protection Agency (EPA) are encouraging states to implement more market-based TCM, such as gasoline taxes or emissions fees, these measures are often costly and economically and politically unpopular; (5) localities that cannot obtain support for market-based TCM can maximize the benefits from traditional TCM by focusing on specific congested corridors and implementing TCM that reduce the number of trips and miles traveled; and (6) more TCM research is needed to determine its overall effectiveness, update literature that is outdated, and help justify future market-based measures.