Geographic and Demographic Profiles of Morning Peak-Hour Commuters on Highways in North Metropolitan Atlanta, Georgia

During the summer of 2006, license plate data on morning peak-hour commuters were collected to assist with the creation of a potential participant pool for the congestion pricing phase of the Commute Atlanta (Atlanta, Georgia) instrumented-vehicle study. The Commute Atlanta study needed to identify census block groups with the highest probability of yielding study participants eligible for recruitment. Approximately 17,000 unique vehicle registration addresses in a six-county area were obtained from the license plates of vehicles observed traveling on several metropolitan Atlanta highways. The data collection enabled further geographic and demographic analyses of peak-hour commuters at the census block group level, providing new insight on limited-access highway commutersheds and demographic characteristics, such as the census block group income distribution, the travel modes, and the travel times of the highway-based commuters who contributed substantially to the region's traffic congestion and worsening air quality. Observation sites were located near the intersections of radial highways and a perimeter highway encircling Atlanta at a 10- to 12-mi radius from the downtown central business district. On average, commuters registered their vehicles (and presumably lived) 13 mi from the observation sites. The registration addresses were located a mean straight-line distance of 4.2 mi from the centerlines of the highways on which they were spotted. Demographically, highway commuter households had incomes 14.4% higher than the average household income, although this percentage varied by observation site. They were less likely to carpool or use nonautomobile forms of transportation on their journey to work, but they were more likely to work at home. Highway commuters were also more likely to report longer travel times to work than their neighbors in the census survey. These findings have implications for congestion pricing and related equity concerns.