Most people who ride transit walk to their local bus stop or train station. Yet in many cities across the United States, transit agencies design stations without much thought for pedestrians or the surrounding neighborhoods. This mismatch results in transit infrastructure that requires users to walk over or under multilane highways to get to stops and produces station platforms located within mere feet of fast-moving cars. This exposes people to noise and air pollution, discourages people from walking, and makes the transit-riding experience a negative one.
In the US, taking transit is often inconvenient or uncomfortable, so residents drive—and pollute—instead. The US Department of Transportation’s new report on decarbonizing transportation shows that the nation is far from meeting its pledge to slash greenhouse gas emissions by 50 percent by 2030. To take steps toward this goal, policymakers could take actions to encourage more transit use and development in areas close to public transportation services, but highways too often stand in the way of both those efforts.
In this post, I show that highway-adjacent rail transit is a fact of life in many metropolitan regions and explain why transit agencies continue to position transit along highways, despite the discomfort that results for their riders and the limitations such locations impose on nearby development. To better serve their communities, transit agencies should consider selecting locations for stations that avoid highways or, at a minimum, protect riders from pollution.
The negative effects of building transit projects along highways
Following World War II, especially after the passage of the 1956 Federal-Aid Highway Act, grade-separated interstates were built through US metropolitan areas. For a few cities, like Chicago, the highway presented an opportunity to build a new (or relocated) transit line that could travel quicker thanks to a straight corridor. Similarly, Washington, DC, sought to create a Metro system “for the motorist,” with stations along roadways accompanied by parking lots. Though DC residents successfully contested most freeway projects in the city, certain suburban Metro portions run along highway medians, with stations served by large park-and-ride garages and connecting buses.
This multimodal model of transit planning was a departure from the prewar norm, which assumed most riders would walk up to stops, as had been the case for the Subway in New York or Chicago’s elevated lines. Fewer than 8 percent of above-ground metro and light rail stations built in the prewar period are located just adjacent to highways, but the share of stations in such locations increased dramatically after the war. Among above-ground stations that have opened since 2020, almost 30 percent are directly along highways, and more than 40 percent are within 300 meters of such roads.
Placing stations along highways enabled cities to build two modes of transportation at the same time, giving drivers an alternative for part of their trips. But such station placement also has negative consequences.
First, locating open-air stations near highways exposes waiting transit passengers to high levels of air and noise pollution. This exposure is not just uncomfortable—it’s also bad for human health and could reinforce social and racial inequities, as transit riders are disproportionately people of color and have lower incomes than average.
Second, highway stations are less convenient for pedestrians. They require people to walk a considerable distance to get onto a platform from nearby buildings. For example, Chicago’s Blue Line Racine station, built in 1958, requires residents to walk more than 300 feet to get across I-290.
Third, stations in highway medians or adjacent to highways offer considerably less opportunity for high-density, mixed-use construction oriented around transit stations. Development along highways is less appealing than in urban environments, which is why property values near highways are lower. Further, highway-based stations have less space available for new housing, offices, and other buildings. Less nearby development, in turn, reduces ridership.
At the Racine station, roughly 1.2 million square feet of otherwise developable land within a quarter mile of the platform entrances is used by the highway itself. Compare that with the Blue Line’s Damen station, which was built in 1895 along an elevated railway above an alley. There, only about 80,000 square feet are used by the track infrastructure within a quarter mile, leaving a lot more room for a more vibrant neighborhood.
The highway near the Racine station also has financial consequences for the city. If developers could use the 1.2 million square feet of land occupied by the highway for housing at even half of the equivalent construction density as is common among projects under construction near transit elsewhere in the city, Chicago could make room for more than 5,000 additional housing units. Those units would add substantial property tax revenue for the city, help it address its housing costs, and give more people the chance to live near transit. But that would require the highway not to be there—or the station to be located somewhere else.
The challenge of planning new transit outside of highway rights-of-way
Despite these limitations, some transit agencies continue to build along highways. In the Seattle region, a light rail extension north to Lynnwood opening this summer is located directly adjacent to the I-5 freeway. Washington, DC’s Silver Line to Dulles Airport, opened in 2022, is largely in a highway median.
Why do some cities continue to locate transit lines in areas directly adjacent to highways, rather than in corridors more accessible to pedestrians? There are a few reasons that stand out:
- Building transit along highways takes advantage of existing, publicly owned rights-of-way, which can reduce construction costs and allow for large park-and-ride complexes that serve drivers. Indeed, much of the postwar argument for placing transit along highways was that it was a money saver. Highways are typically straight and flat, enabling faster transit service.
- Though non-highway-adjacent transit corridors may be more likely to attract nearby development, transit agencies rarely benefit directly from that development, other than through higher ridership. A city’s tax base may increase more after the construction of a transit station on a neighborhood boulevard rather than one on a highway, but transit agencies do not stand to collect much more revenue because they rarely receive funding from property taxes or land sales.
- Building transit on a highway is less likely to produce vocal criticism from the surrounding neighbors than other options, especially elevated lines that are often the subject of fierce opposition and more complicated environmental review processes.
Locating transit systems to minimize rider exposure to highway air and noise pollution
As transit agencies continue to work toward the US government’s 2030 carbon reduction goals, they should consider how transit stations could avoid, or at least minimize, exposure to the negative effects of highways.
One approach is to use the highway right-of-way only for long, fast travel between stops, but then reroute to serve key destinations. Atlanta took this approach when it extended its Red Line north to Sandy Springs in 2000, as did San Diego when it extended its Blue Line to the University of California in 2021.
For stations that remain along highways, transit agencies should consider how to enclose stations entirely to prevent exposure to air and noise pollution. In Montreal, stations along a highway-adjacent metro line currently under construction include platform screen doors that only open when trains arrive.
Finally, when planning new routes, agencies should seriously consider the benefits of identifying nonhighway alignments. Doing so could improve the rider experience and enable more development, a vital consideration given the need for additional housing and the goal of shifting more travel into transit.
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The Urban Institute podcast, Evidence in Action, inspires changemakers to lead with evidence and act with equity. Cohosted by Urban President Sarah Rosen Wartell and Executive Vice President Kimberlyn Leary, every episode features in-depth discussions with experts and leaders on topics ranging from how to advance equity, to designing innovative solutions that achieve community impact, to what it means to practice evidence-based leadership.