Data Sources, Variables, and Model Development
Data for this analysis originate primarily from the 2007/2008 DC Household Travel Survey conducted by the Metropolitan Washington Council of Govern- ments’ (MWCOG) Transportation Planning Board. The survey is representative of the region and consisted of an introductory household questionnaire—which collected demographics and socioeconomics—as well as a travel diary to gather in-depth information on daily travel on a specifically assigned travel day for each household member (MWCOG 2010). The survey collected information on the
Few studies on commuter mode choice concurrently include variables measur- ing benefits for driving, public transportation, walking, and cycling. One study randomly sampled firms identified as “best workplaces for commuters” in several metropolitan areas in the U.S. and found that comprehensive benefit packages could reduce vehicle miles traveled and pollutants by about 15 percent (Herzog et al. 2006). Another study modeled public transportation commuter mode share using worksite-level data from Portland, Oregon, and found public transportation benefits and bike amenities to be significant predictors for commuting by public transportation, walking, and cycling. The study did not assess the provision of worksite-specific free car parking; rather, it attempted to control for free car park- ing via a dummy variable for the downtown “Fareless Square” area, where free car parking was much less likely (Dill and Wardell 2007).