Defining sustainability in transportation : an effort to strengthen MAP-21

The Transportation Research Board of the National Academies identifies nine current and critical issues facing the United States transportation sector: congestion, environmental preservation, deteriorating infrastructure, inadequate funding, social equity issues, susceptibility to natural disasters, insufficient safety improvements, outdated government institutions and a lack of investment in innovation. All of these issues directly threaten the sustainability of transportation in the United States. While numerous transportation stakeholders have presented definitions of sustainable transportation, there is significant variation and disagreement over what sustainability actually means in transportation. The absence of a coherent, universal definition has undermined the overall effectiveness of transportation plans, policies and programs, including the current federal highway authorization, the Moving Ahead for Progress in the 21st Century Act (MAP-21) as well as the Congestion Mitigation and Air Quality Improvement (CMAQ) program. Through examining the definitions of sustainable transportation put forth by the European Union, Transport Canada, the Transportation Research Board (TRB), the American Association of State Highway and Transportation Officials (AASHTO), the Interagency Partnership for Sustainable Communities and various state departments of transportation (DOTs), this report seeks to establish a clear definition of sustainable transportation, adopt applicable sustainable transportation indicators and offer meaningful recommendations that help strengthen the overall sustainability of MAP-21 and the CMAQ program.