University of California Transportation Center

This study examines early trip reduction progress achieved by the Maricopa County Regional Travel Reduction Program in metropolitan Phoenix, Arizona. This study's findings are compared with selected findings about the first year progress of the South Coast Air Management District Regulation XV program in metropolitan Los Angeles.

In Phoenix, non-school employees, by far the largest commuter group, reduced their percentage of single occupant vehicle trips by 3.9%, but their total savings in average single occupant vehicle miles travelled per week was small. School employees reduced their percentage of single occupant vehicle trips by 3.6%, while students reduced this percentage by 13.4%. Both groups contributed at a higher rate to air pollution reduction through average single occupant vehicle miles reduced than non-school employees.

Two inexpensive measures, a guaranteed ride home and prize drawings, were statistically related to a reduced percentage of single occupant vehicle commutes for non-school employees. Both measures were found to be statistically related with trip reduction in metropolitan Los Angeles.

Similar studies conducted in other metropolitan areas are needed to provide additional program comparisons and address the large questions of initial and continued trip reduction progress and urban air quality improvement.