In many cities, highway infrastructure is a reminder of one of the lowest points in the history of planning: highways divided cities in half, destroyed working class neighbourhoods, and cut cities off from their waterfronts. Instead of helping to keep downtowns alive by allowing suburbanites quicker access to shops and services, they allowed drivers to bypass these areas, often generating more traffic and acting as a conduit for further suburban sprawl.

Within the past decade, we’ve begun to see a remarkable development in transportation. In cities around the world, the ubiquitous highway infrastructure that characterized the postwar era has been replaced or removed. Cities and regions have tried to devise methods to deal with decaying structures; in the US, most were constructed in the 1950s and 1960s, while in Canadian cities they did not begin until the 1970s. The most controversial of these highway rehabilitations is the complete removal of the highways. In many cases this seems to be the most cost-effective way to cope with crumbling infrastructure; in other cases, solutions had to be found for highways that had been significantly damaged in earthquakes (Seattle’s Alaskan Way Viaduct and San Francisco’s Embarcadero Freeway come to mind). Some cities, wanting a more seamless network of streets, cycling trails, and walking paths, have decided to replace their highways with underground traffic arteries.

Cities from Oklahoma City to Toronto have been discussing plans to remove aging highways. Oklahoma City, whose 4.5-mile Crosstown Expressway will be demolished by 2012, is merely moving the highway five blocks over to an old railroad line and burying it underground. At grade, the highway will be replaced by a tree-lined boulevard that is hoped to revitalize an 80-block area from downtown to the Oklahoma River. The City of Toronto has been considering the removal of the aging Gardiner Expressway for years.  The Congress for New Urganism even published a top ten list of highways they’d like to see removed to promote urban revitalization: Seattle’s Alaskan Way Viaduct was number 1, the Bronx’s Sheridan Expressway a close second. These schemes are seen as catalysts for urban regeneration. Are they an indication of the type of multi-modal, pedestrian and cyclist-friendly planning that has been gaining momentum for a couple of decades?

Boston’s Big Dig project may give some municipalities reason to pause: the Central Artery (I-93) was rerouted underground at a cost of $22 million, making it the most expensive highway project in the US. Rerouting the highway underground was only one part of the Big Dig: the other components included the construction of the Leonard P. Zakim Bunker Hill Memorial Bridge, the Rose Kennedy Greenway, and the Ted Williams Tunnel. The complex megaproject, initially proposed in 1971 and plagued by engineering and funding complications, was finally completed in 2006. The original construction of the Central Artery (1949-1954) displaced 573 businesses and hundreds of families in the working-class Italian North End of the city. It was chronically congested with east-west and north-south traffic, in part because citizens were so infuriated by it that they managed to stop the construction of further highways linked to the Central Artery in the 1970s, but not before another 4,000 families were displaced.

Designed for a capacity of 70,00, Boston’s Central Artery carried about 190,000 cars per day bin the 1990s. After its redesign underground, travel time across downtown went from 20 minutes down to three. A 62 percent drop in hours spent on the road has resulted in a savings of $200 million annually in time and fuel. The greenway designed at grade level is still not complete, but shows promise in rejoining the city neighbourhoods to their waterfront. Commercial properties adjacent to the Artery have made major gains in property value, and neighbourhoods like the North End have begun to regenerate.

The Infrastructurist recently reviewed four cases of highway removal: Seoul’s Cheonggyecheon Highway, Portland’s Harbor Drive, San Francisco’s Embarcadero and Central Freeways. You have likely seen the remarkable before and after photos of Seoul’s Cheonggyecheon Highway and the river that was restored in its place. The project was completed in 2005, largely at the urging of mayor Seoul mayor Lee Myung-bak, and at a staggering cost of 1.2 trillion won (about $281 billion US). The gorgeous 1000-acre park along the restored river isn’t the only benefit of the highway removal: the road carried 160,000 cars per day and these drivers have in many cases switched to alternative transportation. The number of cars entering downtown has decreased by 2.3%, while the number of bus users and subway users has increased (by 1.4% and 4.3% respectively). Air temperatures are lower. And even more astounding, Lee Myung-bak won the Presidency of South Korea in 2007.

Portland was an early highway removal advocate, replacing Harbor Drive with a greenway in 1978. Harbor Drive, a four-lane freeway built in 1950, carried 24,000 cars a day by the 1970s. It also eliminated pedestrian access to the river. When the state Department of Transportation proposed widening Harbor Drive, the City of Portland resisted. In fact, many called for an elimination of the freeway was a way to replace what had been lost: between 1940 and 1970, the number of housing units downtown dropped by 56 percent, as homes were demolished to build an urban renewal project and the Stadium Freeway (I-405). Retail business had declined significantly. With the help of Governor Tom McCall, Harbor Drive was eliminated in 1974. It was to be a turning point in the planning history of Portland. That same year, the City of Portland voted against the Mount Hood Freeway, the first of several highways proposed by Robert Moses. The federal funding for the freeway was instead used to build the downtown transit mall, eastside light rail, and other transit projects. Tom McCall Waterfront Park, built on the Harbor Drive site, opened in 1978.

San Francisco replaced the Embarcadero Freeway with a tree-lined boulevard, bike trails, squares and plazas. The freeway, built in 1958 amid considerable public resistance, was a double-decker structure that connected drivers to the Bay Bridge, which opened in 1936. The Bay Bridge was also double-decker, originally with a rail line on one level. But when the traffic levels on the bridge reached peak levels in only a few years, the rail line was converted to freeway. Originally the Embarcadero Freeway was supposed to connect the Bay bridge to the Golden Gate Bridge, but after the first section of the Embarcadero was built the city’s Board of Supervisors vetoed any further expressway infrastructure. Although the Board of Supervisors proposed tearing the freeway down in 1985, the motion was defeated; it carried 70,000 cars per day at its busiest point. In 1989, when the freeway was severely damaged in an earthquake, there was a debate over its fate. It was eventually decided that the freeway would be taken down in 1991. Streetcar lines, which had served the busy port area in the pre-Bay Bridge era when it was bustling with ferry traffic, were rerouted along the new boulevard. The freeway’s removal also spurred a resurgence in residential living. Traffic has been absorbed by the adjacent streets, and BART ridership has increased by 15%, all at a cost of less than $50 million.

The removal of the Embarcadero Freeway may have also inspired the removal of San Francisco’s Central Freeway, which was also damaged in the 1989 earthquake and subsequently closed. Like the Embarcadero, it was a spur highway built as part of the larger unbuilt freeway plan. Despite this, the debate over its removal was fierce. It was finally taken down in 1992 and replaced by Octavia Boulevard, which handles a smaller traffic volume and protects cyclists and pedestrians from car traffic. In addition to this, a short section of the freeway was replaced.

These highway replacement and removal projects can be seen as an effort to reclaim inner city neighbourhoods, but they are also part of a larger movement that acknowledges the importance of many different transportation modes. The rehabilitation of these highways has in most cases been fraught with political tension. In some cases compromises were reached, and replacement instead of complete removal was the end solution. In the cases where highways were removed, the dire predictions of cities overrun by traffic have been proven to be false. The Portland and San Francisco cases remind us that the highways were originally constructed amid public opposition, and that in some ways they represent a turning point in the history of urban planning. The construction of these “gateway” highways inspired public resistance to further highway infrastructure, preventing entire city centers from being destroyed by the octopus-like arms of high-speed concrete. Public support for highway replacement and removal has been critical in each case, but the political sway of individual politicians and city administrations has also been instrumental. These cities have proven that traffic engineers’ predictions of traffic volumes (wait for it) don’t seem that accurate after all.

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