AASHTO BLR-4:2009 TRANSPORTATION-Are We There Yet-The Bottom Line Report.
The analysis of future vehicle miles of travel and other dynamics which will determine highway and transit needs takes into account many rapidly evolving factors:
• It incorporates research used by the National Surface Transportation Policy and Revenue Study Commission, “Transportation for Tomorrow,” 2008, to develop forecasts of VMT.
• Recent trends in vehicle miles of travel, transit ridership, per capita incomes, and fuel prices have been used to shape the forecasts for the next six years of authorization and for the 20 years of highway and transit investment needs.
• Ten-year trends in the growth of vehicle miles of travel for the United States through 2007 were at 1.6 percent per year, and six-year growth of VMT has been an average of 1.2 percent per year. VMT has declined from 3 trillion in 2006 to 2.9 trillion in late 2008.
• Ten-year growth trends in transit ridership have been at 2.4 percent average per year, which is well above the base case numbers used for all recent transit needs analyses.
• Clearly, previous forecasts need to be adjusted to reflect the factors that are driving VMT growth and transit passenger growth. At the same time, the declining VMT trend seen over the past two years is not expected to continue for the next 20 years.
Past Forecasts ofVehicle Miles of Travel
Between 1993 and 2004, highway vehicle miles of travel (VMT) grew at an annual rate of 2.3 percent. This was slower than the rates for the two previous decades. The 20-year forecasts made by U.S. DOT in 2004 called for future growth rates of 2.02 percent. By the time of their 2006 report, they had reduced their forecast to 1.91 percent. More recent trendlines have pointed to an even slower future rate of VMT growth.
The forecast sources utilized for the previous Bottom Line Reports and the U.S. DOT’s Condition and Performance reports have been the annual Highway Performance Monitoring System (HPMS) data sets submitted by the states to the FHWA. The HPMS data submitted by the states includes information on a sample of highway segments in each state.
A projection of 1.4 percent growth in VMT is the base case for highway VMT growth used here.3 In addition to this base case, needs analyses have also been conducted for a future VMT growth rate of 1.0 percent per year (effectively constant VMT/per capita with population growth at about 1 percent. AASHTO studies have shown that holding the rate of growth in VMT to under 1 percent annually will help reduce greenhouse gas emissions, a part of the transportation sector’s strategy to be helpful regarding global climate change). A forecast of 1.91 percent growth, which is the HPMS forecast, was also analyzed. In addition, a no growth forecast, holding VMT at present levels has been developed to help understand the nature of underlying needs in the backlog.AASHTO BLR-4 pdf download.