• VMT Growth and Improved Air Quality: How Long Can Progress Continue?This booklet explains the relationship between growth in vehicle miles traveled (VMT) and air quality. By showing past trends in air quality improvement nationwide and future emissions reduction trends, it is useful to State DOTs and MPOs in transportation investment decisionmaking. Atmospheric levels of all four pollutants to which motor vehicles contribute significantly—airborne lead, carbon monoxide, nitrogen dioxide, and ozone—have declined consistently for almost 2 decades. In addition, violations of the National Ambient Air Quality Standards for airborne lead, carbon monoxide, and nitrogen dioxide have been virtually eliminated. Controlling ground-level ozone (or “smog”) has proven more challenging, but violations of the Federal ozone standard have decreased. Most of the reductions in atmospheric concentrations of these pollutants can be attributed to lower emissions by motor vehicles. Since 1970, tighter emissions standards for cars and trucks have significantly reduced vehicular emissions of carbon monoxide and volatile organic compounds (VOC, a primary ingredient of ozone). This analysis examines whether reductions in motor vehicles’ VOC and oxides of Nitrogen (NOx) emissions rates—which are likely to result from recently adopted control strategies—could be offset by continuing growth in vehicle miles traveled during the foreseeable future. It also investigates how rapidly motor vehicle emissions of various pollutants might resume growing if their long-term decline is reversed, and compares the potential future increase in emissions to their historical decline. Finally, the analysis explores how this potential increase in motor vehicle emissions might be postponed by further tightening of new car emissions standards or other proposed emissions control strategies that have not yet been adopted. In summary, the analysis shows that emission control measures already in effect are likely to extend the decline in motor vehicles’ VOC emissions for at least another decade, and further tightening of new car emissions standards could prolong this decline by approximately another 10 years. In the case of NOx, tighter standards for new vehicles (trucks and automobiles) are likely to be necessary to achieve the same result, although significant emissions reductions from off-road vehicles and equipment should also be possible. • Transportation and Air Quality Public Education CampaignThis FHWA initiative, in partnership with the Federal Transit Administration and the EPA, is a multiyear effort to support national environmental and transportation objectives through a campaign to increase awareness of the link between travel behavior, traffic congestion, and air quality. The goals of the public education campaign are to improve citizens’ quality of life, health, and the environment through education; increase the awareness of alternative travel modes and the importance of travel choices; and encourage positive behavioral change to reduce transportation-related emissions. The public education campaign, which is conducted at national and local levels, includes advertising as well as pilot tests, with participants representing a broad coalition of interests. The key benefits expected from this initiative are enhanced national and local government partnerships; leveraged resources from a variety of sources; and establishment of a national, sustained effort to reduce emissions and traffic congestion through lifestyle choices and related changes in travel behavior. • Wetland Mitigation DatabaseThe FHWA has recently published a wetlands mitigation accounting database entitled, System for Wetlands Accounting and Management Program, for recording and analyzing wetland mitigation efforts. The program will greatly facilitate wetland mitigation recordkeeping and reporting of |