Access Across America: Auto 2022, which estimates the ability of people to connect to opportunity via the road network, shows that access to jobs by automobile fell in all the top 50 US metropolitan areas. The highest reductions in access to opportunity were associated with those places in which traffic congestion had increased the most.
For example, compared to 2021, the typical worker in the Los Angeles region lost access to 1.2 million jobs within a 30-minute drive—a 40% reduction. Similar patterns were observed in Boston (33% reduction) and Atlanta (28% reduction), among other cities. These drastic changes measure the impact of the return of traffic, magnified by the difference from unusually high job accessibility by auto during the first 21 months of the pandemic.
Los Angeles, New York, and Dallas remained the top three urban areas for auto access to jobs. That means, despite high congestion, residents with a car and the means to operate and park it, would still find the best overall access to destinations in these urban areas. San Jose and Chicago, also with notable congestion impacts on accessibility, rounded out the overall top five best places to reach opportunities with a car.
Places like Riverside, California, and Miami, on the other hand, were in the top five for the worst congestion impacts, while being far down the list in overall access to opportunity. In urban areas like these, the burden of slow travel is not offset by the number of opportunities that can be reached in a reasonable time.
Larger, denser cities typically experience greater congestion than smaller cities. But within this overarching trend, variation in the arrangement of land uses, road network structure, traffic management practices, and the provision of alternate transportation modes allows individual cities to experience greater or lesser congestion impacts than their size would predict.
For example, Miami ranks 23rd by job accessibility by auto but 4th by congestion impact, indicating that congestion may play a relatively larger role in limiting local access to jobs than in other cities. Conversely, San Jose ranks 4th by job accessibility but 19th by congestion impact, suggesting that job accessibility was influenced less by congestion there during this time period than in other cities.
In general, most cities exhibit a “ring of congestion” effect, where workers departing from Census blocks closer to a city center or central business district experience smaller losses in accessibility than those departing from Census blocks some distance out from the city center. However, within cities characterized by a less concentrated central business district and more uniform density across a wider area of the city, such as Atlanta or Los Angeles, this effect of reduced loss of accessibility due to congestion within the city center is mitigated, and congestion impacts appear more evenly distributed throughout the city core and surrounding area. The placement and concentration of congestion impacts changed noticeably during the COVID period in many cities.
Key factors affecting the rankings for any metro area include the number of jobs available and where they are located, the road network structure, traffic management practices, the provision of alternate transportation modes, and population size, density, and location. Better coordination of transportation systems with the location of jobs and housing will improve job accessibility by auto.
The findings have a range of uses and implications. State departments of transportation, metropolitan planning organizations, and local government agencies can apply the evaluations to performance goals related to congestion, reliability, and sustainability. In addition, detailed accessibility evaluation can help in selecting between project alternatives and prioritizing investments.
The research is sponsored by the National Accessibility Evaluation Pooled-Fund Study, a multi-year effort led by the Minnesota Department of Transportation and supported by partners including the Federal Highway Administration and additional state DOTs.
