Self-Healing Roads: Strong Track Record of Success for Highway Removal

The idea that a highway segment can be replaced with an urban boulevard without creating significant traffic problems strikes some people as unlikely.  Time and again around the world, though, highway removals have shown traffic patterns to be flexible and adaptive, with doomsday predictions of gridlock proving false.  This “self-healing” nature of road networks suggests that City to River’s proposal to replace the downtown portion of (soon-to-be-former) Interstate 70 with an urban boulevard is likely to cause minimal adverse effects on the vast majority of drivers traveling through the St. Louis area.

Although it seems counterintuitive, many traffic experts understand that creating more road capacity via highways actually tends to increase congestion in urban areas.  Highways force (or, at least, cause) too many drivers to use a single route that often has inadequate access points to a city, rather than distributing the traffic more evenly over a network of roads.  High-speed routes introduce inefficiencies by inducing drivers to go out of their way in an attempt to save a minute or two, as opposed to taking a more direct route on local streets.  Even the mere ability of drivers to move faster can cause traffic problems.  As explained in a 2006 SmartMobility report, “[s]peed is confused with capacity.  An urban street can carry more vehicle traffic at 30 m.p.h. than it can at 50 m.p.h. because the capacity is controlled at signalized intersections.”

More and more cities are recognizing the problems caused by highways cutting through their urban cores, and the benefits that can be achieved when those highways are removed.  Highway removal and restoration of the urban grid thus has become a preferred choice for an ever-growing number of cities.  Even the U.S. Department of Transportation has recognized that replacing an urban highway with a surface boulevard is the more financially and environmentally sensible choice for some cities, and is consistent with USDOT’s goal of ensuring that “[p]edestrians, bicyclists, motorists and public transport users of all ages and abilities are able to move safely and comfortably along and across a complete street.”

When a highway is eliminated, traffic tends to adapt quickly.  Drivers spread across grid networks, with replacement streets serving much of the same traffic and previously underutilized routes absorbing the rest.  Often, traffic in the impacted area appears to simply “disappear,” as drivers adopt alternative routes, travel times, and even modes of transportation.  As noted in a 1998 study that analyzed the effects of seventy cases of reduced road capacity (although not necessarily highway removal), “traffic problems are usually far less serious that predicted,” and “widespread, long-term disruption is hardly ever reported.”

These are more than abstract theories, but rather have been proven time and again in successful urban highway removals around the world.  Here are just a few examples of highway removals that have not caused the major traffic problems predicted by experts and feared by the public:

Harbor Drive, Portland Oregon

Harbor Drive, Portland, Oregon: In 1942, the four-lane freeway known as Harbor Drive was completed along the Willamette River, cutting off pedestrian access between the river and downtown Portland.  By the 1970’s, about 24,000 vehicles (including 2,500 heavy trucks) used the highway daily, with projected traffic of 90,000 trips per day by the 1990’s.  As a result, the idea of closing Harbor Drive was considered “impossible” when beautification of the area was first proposed in the 1960s, with predictions of massive traffic backup from traffic engineers and political leaders.

Proponents of highway removal continued to argue that the Portland highway system had excess capacity and could handle the traffic that would be diverted from a closed Harbor Drive.  The city ultimately agreed, and in 1974 Harbor Drive became the first major highway to be removed intentionally.  The replacement of Harbor Drive with an at-grade boulevard (the adjacent Naito Parkway) resulted in significant increases to nearby property values, and the development of McCall Waterfront Park in Harbor Drive’s former footprint has been credited as a major cause of the revitalization of downtown Portland.  And the effect on traffic?  In the words of Portland Traffic Engineer Don Bergstrom, who had previously declared the removal of Harbor Drive to be impossible, “there wasn’t a ripple.”

Embarcadero, San Francisco

Embarcadero Freeway, San Francisco, California: For decades, the Embarcadero Freeway cut off physical and visual access to the San Francisco Bay, but fears of gridlock killed proposals for its removal.  Those fears disappeared after the freeway was damaged by the 1989 Loma Prieta earthquake, with traffic quickly adjusting to the inability to use the freeway.

With traffic concerns mitigated, the freeway was removed in 1991 and replaced with a surface boulevard.  Adjacent property values went up by 300%, leading to enormous development in nearby neighborhoods and a renaissance of the waterfront (including the renovation of the Ferry Building and various piers for mixed-use development).  Today, the boulevard accommodates large volumes of traffic, pedestrians, cyclists, and public transportation alternatives, and is considered a huge success by almost all San Franciscans.

Octavia Boulevard, San Francisco

Central Freeway, San Francisco, California: Like the Embarcadero Freeway, San Francisco’s Central Freeway was damaged and closed as a result of the 1989 Loma Prieta earthquake, triggering a battle over whether to remove or rebuild it.  When the freeway—which accommodated 97,00 cars per day—was finally closed for demolition and later replaced by the new Octavia Boulevard, fears of “unprecedented” gridlock were shown to be baseless.  Total traffic volumes were reduced, with the street grid successfully distributing and absorbing the remaining traffic.  Commenting on the smooth transition, a California Department of Transportation spokesman said, “We have a traffic phantom out there.  We don’t know where everybody went.”

Consistent with other case studies, removal of the freeway directly resulted in the significant revitalization of neighboring areas, including the now-vibrant Hayes Valley neighborhood.  Additional benefits include the residential development of seven acres of former freeway right-of-way, plus revenues to the city from sales of freeway parcels.  As noted in a 2007 update by the San Francisco Municipal Transportation Agency, “on balance, removal of the freeway provided a range of benefits to the community without substantial negative impacts for commuters.”

West Side Highway, New York, New York: New York City’s West Side Highway, the first elevated highway, partially collapsed in 1973.  After a decade long battle to rebuild the highway, it was finally demolished and replaced with an improved West Street (the boulevard that ran under the elevated highway), public park, bike path, and pedestrian promenade along the Hudson River.  As noted by the Preservation Institute, “53 percent of the traffic that had used this highway disappeared, dramatic proof that building freeways generates traffic and that removing freeways reduces traffic.”  In a 2007 interview, transit guru and former NYCDOT Chief Engineer “Gridlock” Sam Schwartz said that “over time, we didn’t see any increase in traffic: the other avenues absorbed it and we weren’t able to trace it . . . . a highway carrying 80,000 vehicles a day collapsed and . . . nothing.  We couldn’t even measure a change in speeds!”

Park East Freeway Demolition, Milwaukee

Park East Freeway, Milwaukee, Wisconsin: Built in 1969, the Park East Freeway isolated Milwaukee’s north side, disrupted the street grid by permitting access to downtown at only three points, and acted as a barrier to the city’s redevelopment efforts.  Although the freeway was used by an average of 54,000 vehicles per day in 1999, it was removed a few years later and replaced with a landscaped boulevard at a fraction of the cost of rebuilding the deteriorated freeway.  As a result of this effort led by visionary Mayor John Norquist, the urban grid was restored (thus mitigating traffic impacts by creating better connections to existing streets), the value of adjacent properties skyrocketed, and dozens of acres of newly-developable land attracted hundreds of millions of dollars of investment.

Again, these are only a few examples of successful urban highway removal; similar results have occurred in other cities around the world, with many other proposals in the works.  Although it is difficult at this point to predict the specific ways in which St. Louis drivers would adapt to a new Memorial Drive, there are several reasons to be optimistic that the region will experience the same significant benefits and minimal negative impacts that have occurred elsewhere.

First and most importantly, before the downtown portion of the highway will be removed, Interstate 70 will already have been rerouted north of downtown over the new Mississippi River bridge that is slated for completion in early 2014.  Once the bridge is open, “through” traffic on Interstate 70 will not use the elevated and depressed lanes that cut through downtown, reducing the traffic on those lanes.  Those lanes would be renamed (most likely to Interstate 44) and would serve only as an access point to downtown and a connector between Interstate 70 and Interstates 55 and 44.

Second, for those drivers who would continue to use the highway segment as a way to enter and leave downtown, the new boulevard will create many more points of access than currently exist.  In its current state, the highway allows drivers to enter and leave downtown at only a few points.  A new Memorial Drive, on the other hand, will greatly increase the number of east-west connectors into downtown.  The boulevard would be a main downtown circulation route, connecting the riverfront, the Archgrounds, Laclede’s Landing, Washington Avenue, Lumiere Casino and more.  Given that the vast majority of traffic using the downtown highway is in fact heading into and out of downtown and adjacent neighborhoods, connecting the downtown grid to an accessible north-south route will ease drivers’ ability to get where they are going. 

Third, the nature of St. Louis’s road and highway system suggests that removal of less than a mile and a half of the downtown highway will cause minimal disruptions even for those drivers who currently use it as a connector between Interstate 70 and Interstates 44 and 55.  Most experts agree that St. Louis’s street grid is underutilized and has excess capacity. In addition to the new Memorial Drive (which will be a high-traffic boulevard with well-timed signalized intersections), drivers traveling between the north and south sides of St. Louis will be able to take advantage of other existing routes (e.g., Jefferson Avenue, Truman Parkway, Broadway Street, and 4th Street) that will likely add only a few minutes of extra travel time than the existing highway.

The benefits of removing Interstate 70 are clear: our city will finally be reconnected to its greatest natural and manmade assets, and enormous investment and development opportunities will be created.  Real-life case studies have shown that removing highways from urban cores tends to cause property values to soar and significant redevelopment in impacted areas.  There is no reason to believe that St. Louis will have a different experience; in fact, a leading real estate consultant has identified $1.2 billion in development potential over the next 20-25 years as a result of the implementation of City to River’s proposal.

Nonetheless, a project of this magnitude will not happen without a reasonable basis for believing that those benefits will far outweigh any negative impacts on traffic.  City to River strongly believes that this will in fact be the case, with traffic easily adapting to new circumstances.  Of course, this is not a matter of City to River simply saying, “trust us”—we believe that the comprehensive traffic studies that will be necessary for this project will reach the same conclusions that we have.  But, preliminarily, does the evidence make it more reasonable to believe that St. Louis will experience the same positive, surprising results shared by many other cities—or that our downtown area will become plagued by the gridlock that has failed to materialize in larger, more congested cities around the world?

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