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The Vicious Cycle of Urban Highway Expansion

Traffic southbound on Interstate 5 near the Rose Quarter. A proposal calls for the expansion, covering, and soundproofing of I-5 in the area, leading to more spending on car-centric urban design. Photo by Luke Ramsey.

The Oregon Department of Transportation (ODOT) has been taking steps to expand I-5 near the Rose Quarter, in Northeast Portland, in order to reduce traffic congestion and fix the ongoing traffic bottleneck issue between I-84 and I-405. In order to fix this problem, they plan to add auxiliary lanes and shoulders. They call the project the “Rose Quarter Improvement Project,” but a more apt name would replace “improvement project” with freeway expansion. It will contribute to the continuing creation of a car-based world, at a time when we should be moving away from automobiles. Urban freeways are unsafe, they damage the environment, and they are in no way practical. 

The estimated cost of the renovations is unclear: ODOT’s website states that it will cost $450 to 500 million, while Oregon Transportation Commission (OTC) chair Bob Van Brocklin estimated during an interview with Oregon Public Broadcasting (OPB) that it could cost more than $750 million, and other estimates put the cost at more than a billion dollars. Regardless of the specific number, the changes will have a significant impact on both the city of Portland and the Oregon state budget.

Most American cities are designed to facilitate the movement of large individual vehicles over all other modes of transport. Freeways reinforce this car dominance, as they take up large spaces that are almost entirely closed off to pedestrians, with the exception of noisy overpasses. Cars have become ingrained into the American psyche as the lone reliable way to move people from Point A to Point B, but in cities that is not the case. Freeways are unable to sustain as much movement, while avoiding gridlock, as an effective system built on walking, biking, and public transit can, and unlike those other systems, they eat up vast expanses of valuable space in cities.

Most freeway projects involve heavy spending on expansion to relieve congestion. The theory is that as the freeway adds more space, cars will have more space to move. However, actual freeway expansion projects are much more complicated than this. As space is added in the form of new lanes, more drivers will decide to take that road instead of taking another road or not driving at all. In other words, the demand will increase. In a 2009 study, Gilles Duranton and Matthew A. Turner of the National Bureau of Economic Research found that as lane miles are added to a freeway, demand rises by an equal amount, entirely negating the potential congestion-related benefits of expansion. This process is also known as “induced demand.” While expanding freeways does allow them to move a greater volume of people, other modes of transportation, namely transit, walking, and bikes, are capable of handling demand much more effectively.

Freeways are often viewed by Americans as the primary option for the movement of people through urban and rural areas. However, there are many superior alternatives. Transit systems like New York’s have an incredible capacity to move people, without ever running into the congestion issues that plague cities designed around car travel. The New York Subway system would move more than 4.5 million people on an average pre-pandemic day, according to data from the Metropolitan Transportation Authority (MTA), which runs the Subway system. Meanwhile, the entire Los Angeles interstate system, the nation’s most-used, moved around 310,000 people per day in 2017, based on data from the Federal Highway Administration.

ODOT estimated that the expansion project would save drivers nearly 2.5 million hours per year by reducing congestion. Rose Quarter Project Manager Megan Channell states that this estimate is based on traffic modeling: “…it kind of builds on the traffic model sort of approach… by way of comparing the two long term scenarios…it looks at [what traffic volume and vehicle speeds look like today]… and then comparing that to the model that was developed [for 2045 with the changes made by the project].” According to Channell the models are, “the regionally adopted process that any transportation project would use, developed by the Metropolitan Planning Organization (Metro), the regional travel demand model, and then building from that.”

The model used by ODOT found that while the new development would slightly increase demand on the freeway, the expansion would not increase the total number of cars but would rather encourage people to take the highway in lieu of other routes. “It’s putting those vehicles that are currently on the local system back onto the interstate, really where they should be,” says Channell.

However, traffic is extremely difficult to predict, and their model points to another issue with expansion projects: because it’s almost impossible to predict how traffic levels will change in the real world, engineers use predictions that may be false to justify their expensive plans.

While there are some elements of design that can be accounted for, cities are unpredictable, and there are a variety of potential fluctuations in demand that no model could possibly account for. To make up for this, engineers must resort to “projecting the future traffic by applying a ruler to past data,” writes Charles Mahron, Jr., in his book “Confessions of a Recovering Engineer.” Mahron founded the advocacy organization Strong Towns in 2009 to promote changes to American and Canadian streets. He sums up traffic projection models by writing, “cities and states spend enormous sums of money doing this work, yet a competent third grader with a straightedge could predict just as well.”

The model being used for the ODOT project predicted a difference in traffic patterns with and without changes, calling them the Build and No-Build alternatives. However, “the No-Build Alternative consists of existing conditions and other planned and funded transportation improvement projects that would be completed in and around the Project Area by 2045,” according to ODOT’s Traffic Analysis Technical Report. Predicting future projects like this is an extremely difficult task, if possible at all, which makes projections about changes to traffic even more difficult.

Perhaps the most insidious impact of the individual automobile is its effect on air and noise pollution. Cars combine the use of fossil fuels with almost no economy of scale, moving just 1.5 people on average, according to the University of Michigan, and weighing an average of more than two tons, per Environmental Protection Agency (EPA) data. The weight of the vehicles takes a toll on roads, and tires moving on asphalt generates an unhealthy amount of noise. A study in Oxford’s European Heart Journal found that London residents who faced long-term exposure to noise from traffic were somewhat more prone to cardiovascular issues and strokes than those further from the noise, especially the elderly. Noise from roads is a public health risk.

ODOT also intends to mitigate the community and environmental impact of this expansion with a variety of changes to the streetscape. They will add a freeway cap, a cover over parts of the road containing usable streets, over some parts of the area. These streets will be more walkable than the existing network of overpasses and will be able to support some new development. The Rose Quarter project does also make an effort to alleviate risk factors related to noise by adding sound barriers that they say will reduce the amount of noise in surrounding neighborhoods.

While the additions of a highway cover and sound walls will help the community, expanding the highway will end up encouraging more driving. The project may be in some ways beneficial, but it reflects an attitude shared by many Americans that urban streets and roads should be designed to facilitate the movement of cars. Cars are not the best way to move people within a city, and urban freeways have fractured the American cityscape. 

Cars also pose a greater threat to the environment through air and greenhouse gas pollution than just about any other mode of transport. This became an issue at Portland’s Tubman Middle School, which is located just next to I-5 in the Rose Quarter corridor. A 2018 study found elevated levels of air pollutants on Tubman’s campus and recommended that “student outdoor activities be limited at HTMS [Harriet Tubman Middle School], especially during high traffic periods.” A filtration system was added indoors, but the air in some areas outside remains unhealthy. With the support of Oregon governor Kate Brown, PPS intends to relocate the school. Channell supports the relocation as well, conceding that “having a school immediately adjacent to a highway is not a good condition.”

Urban freeway development meant bulldozing parts of the city, often places near the city center. This was not an easy task in some places, including Portland, where citizens were able to mount successful resistance movements. To combat resistance to urban highway development, designers developed in the parts of the city with the fewest resources: lower-income and majority-non-white neighborhoods. It took removal of black people from their homes through eminent domain, and bulldozing of black communities, to build much of the urban freeway system in the United States.

The relocation of Harriet Tubman Middle School, where students are almost four times as likely to be black as the district average, illustrates the trap that is urban freeway design. Once a freeway is added, it begins to cause problems for the neighboring community, which leads to more spending on fixes like soundproofing and school relocation. It invites traffic and causes congestion, which planners then respond to by adding more lanes, but that induces demand, which leads to more congestion, and additional lanes, and the vicious cycle continues. When cities get roped in by the lure of interstates, they may not be able to escape. This has happened throughout the United States, especially in the Sun Belt, or the southern regions of the US, where rapid postwar migration has enabled the sprawl that subsidizes urban highways. About half of all vehicle miles traveled by car take place on freeways in metro areas like Dallas-Fort Worth, Los Angeles, Houston, the Bay Area, and many others, according to the Federal Highway Administration. In these cities, large areas that could be controlled by the people are instead dominated by cars, because of repeated infrastructure projects that created a feedback loop of bulldozing and displacement. It’s time to break that loop.

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