Travel demand has grown steadily in the United States in the past few decades, mirroring the positive trends in economic growth and an increase in the use of personal vehicles for commuting trips and other trip purposes. However, recent research has highlighted significant modifications in these trends, suggesting a “Vehicle Miles Traveled (VMT) Peak” in the first years of the 21st century. Several possible explanations have been proposed for the recent car-use peak, including the impact of the recent economic recession and the increases in fuel prices, as well as the impact of high traffic congestion in large metropolitan areas, the possible substitution of physical trips with electronic (virtual) alternatives to travel, the possible substitution of ground transportation with airline travel, changes in the urban form of cities and metropolitan areas, more restrictive (and expensive) driver’s licensing regulations, employment trends, trends in household formation and composition, and shifting personal preferences and lifestyles of the U.S. population. This white paper summarizes the findings from the recent studies in this field, and presents a research agenda designed to clarify the reasons for the current VMT peak and to assess the implications for future passenger travel demand in the U.S.
