Making an Impact
In 2006, ACCS embarked on an extensive research and evaluation program to measure its success in meeting customers’ needs and document the travel and environmental impacts of mode changes influenced by TDM services. ACCS conducted surveys of residents, employees, service users, and employers to measure their awareness and use of TDM services, their satisfaction with the services, and their travel patterns before and after their contact with the program.
The research demonstrates the value of these cost-effective services to individual users and the collective value of the travel changes made by these users to achieve County-wide transportation and environmental objectives. These reports highlight ACCS’ significant accomplishments and impacts in FY 2008 and beyond, as measured by those surveys and other data collected.
The impacts presented on the previous pages were calculated by applying a set of multiplier factors developed from surveys of customer groups to program activity data from ACCS’ tracking systems. These steps are:
1) Estimate commuter population “base”—This is the population of travelers who have used each program (e.g., Commuter Store customers, Bike Arlington participants, etc.)
2) Estimate “placements”—Multiply the population base by the “placement rate” (percentage of population who made a travel change as a result of the program)
3) Estimate vehicle trips reduced—Multiply number of placements by a vehicle trip reduction (VTR) factor equal to the average daily vehicle trips reduced per placement
4) Estimate vehicle miles traveled (VMT) reduced—Multiply number of vehicle trips reduced by average travel distance
5) Estimate emissions reduced—Multiply vehicle trips and VMT reduced by emissions factors for the Washington DC metropolitan area
6) Estimate energy (gasoline) savings—Divide VMT reduced by average passenger fleet miles per gallon of 23.8 (source MWCOG)