Elevated Barriers

Double deck elevated approach to the San Francisco Bay Bridge

In recent decades there has been an active effort worldwide to remove elevated highways. Many constructed earlier in the 20th century to speed traffic are now seen as obstacles to vibrant urban development.

From the United States to Korea, there has been a new awareness of certain unintended consequences of these projects originally designed to overcome traffic congestion. These expensive and massive highway structures were found to be a medicine more devastating than the congestion disease.

Interestingly, Mayor Lee of Seoul, Korea, who was responsible for the elevated highway removal in that city and the creation of a riverside park upon the former highway site, was elected Korea's president in December 2007.

San Jose - The above elevated highway [pictured from space] separates downtown San Jose from a primarily Hispanic section of the city. Beneath the highway may be found temporary storage space for various construction projects. Under the imaged segment is a paved street and an unpaved walkway.

There is no sense of welcome to the downtown. Although actual passage beneath the highway at street level is possible, it is not a pleasant experience. Whether conscious or not, the elevated highway acts as a barrier to the flow of energy between the resurging city heart and this neighborhood. There is no attempt to construct connections (such as an open market) that could pull the city together beneath the concrete behemoth.

The scenes below from Google Earth are of various world cities. The key constant in each of the images is the presence of an elevated highway separating the heart of the city from the waterfront. (To ease seeing the subject highway, a yellow highlight has been added over the highway structure.) The cities are unnamed, but the Discussion of City Images gives the solution. See if you can guess the answers based on the image and the following commentary.


This city is famous for its beaches and magnificent setting. The elevated highway separates the historical city heart from the bay.	This city core is on an island in a river. The city has tried to open up river access at a number of places along this elevated highway .	This city has talked for years about removing the viaduct. The most significant obstacle seems to be cost.

There is more than an elevated highway walling off this city from its lake frontage. Note the railroad tracks entering and leaving the station adjacent to the city core.	This elevated highway runs along the entire river frontage. The city is planning new highways of this sort rather than reconsider the approach.	This city is actively looking for ways to revive its moribund downtown, including removal of the elevated highway.

Discussion of City Images

There are no current plans to remove the highway barrier along Rio de Janeiro's waterfront. New York City is incrementally opening up public access to segments of its East River waterfront despite the barrier of the Franklin D. Roosevelt Drive. Seattle has talked for years about removing the Alaska Viaduct. High cost keeps stymying the effort. Toronto also has been reluctant to move forward on removal due to costs. It is now considering building around the problem. In Taipei the elevated highway separates the city from the Tamsui River. The city appears to have not learned any negative lessons from the experience because it is planning a new elevated highway along the Xindian River. Buffalo is actively searching for solutions that involve the removal of its elevated highway.

San Francisco


These two photos were taken from Coit Tower on the top of Telegraph Hill some 25 years apart. As new development occurs along the now open corridor where the Embarcadero Freeway once stood, the benefits of tearing down the freeway become increasingly evident.

The upper image shows the Embarcadero elevated freeway around 1960. Note the Southern Pacific building with its 'S-P' sign on the roof. The lower image shows the scene in front of the Ferry Building circa 2005. The former S-P building is missing its sign and has a few additions.

The San Francisco waterfront was blocked off after the Embarcadero Freeway was constructed in the late 1950s. There was a dreary darkness associated with the spaces beneath and the buildings under the shadow of this massive structure.

If it wasn't for the San Francisco citizen revolt that followed its construction, the freeway would have eventually walled off the waterfront as far as the Golden Gate. As it was, it extended more than half a kilometer north of the Ferry Building before it turned inland to its terminal off ramps.

The 1989 Loma Prieta earthquake damaged the structure. At first the State of California planned to retrofit and retain the two-decker freeway. Then Mayor Art Agnos proposed demolishing the freeway in favor of a boulevard with a large plaza in front of the Ferry Building.

Opposition to demolishing the freeway came from Chinatown and the city's downtown businesses. Agnos continued to negotiate with federal and state officials to win enough funding to make the demolition practical. The opposition quieted. Demolition began in 1991.

On June 16, 2006, the Port of San Francisco unveiled a monument to Mayor Agnos honoring his vision and courage, noting "This pedestrian pier commemorates the achievement of Mayor Agnos in leaving our city better and stronger than he found it."

The city and its downtown and Chinatown businesses seem to be surviving quite nicely with this renovated Embarcadero. The images below portray the new Embarcadero no longer shadowed by the elevated behemoth.



The top view is looking north along the Embarcadero toward the Ferry Building. The inset is an aerial view of the background during the period when the Embarcadero Freeway still existed. The lower left view is just south of the Ferry Building looking south toward the Bay Bridge. Note the bow and arrow structure at the far left side of the image. The lower right image is of the Audiffred Building, which I well remember darkened by the shadow of the former elevated highway.

Sidelight - An Urban Design Experiment

Interestingly, an experiment occured in 1978 (More than a decade prior to the Loma Prieta Earthquake) which tested in San Francisco an urban design theory involving an elevated highway. The subject of the experiment, by UC Berkeley graduate students and their professors, was the San Francisco waterfront between the Bay Bridge and the Ferry Building. The experiment assumed the continued existence of the Embarcadero Freeway. The object was to see how hypothetical development might occur around the freeway if the rules set forth in the experiment were implemented. The experiment is documented in A New Theory of Urban Design by Christopher Alexander, et al, 1987. The experiment location and an image of the model presenting the results are found below.

The area subject to the urban design experiment is outlined in orange. The route of the Embarcadero Freeway is highlighted in yellow. The route of the Bay Bridge is shown with dashed lines near the top. Part of the Ferry Building is represented by the black shape nearest the lower left corner of the image. Spear Street defines the western boundary opposite the waterfront.

This view of the completed model of the experiment results was taken from above the location of the Bay Bridge looking northwest. The Ferry Building is at the top just outside the view encompassed by the image. The route of the Embarcadero Freeway is highlighted in yellow. The urban development created by the students flows through and under the freeway. The psychological barrier it represented is eliminated. The envisioned waterfront area is connected to the rest of the city and includes elements that have been shown through the experience of other urban areas to result in a rich and thriving urban experience. If the students had assumed taller buildings similar to those rising in San Francisco today, the resultant development could even have flowed over the highway structure.