Lesson No. 1 ||| Don't Bulldoze Houses for Roads
(L-R) The Cross-Bronx Expressway, New York City; The Alaskan Way Viaduct, Seattle
The Offenders: The Cross-Bronx Expressway, New York City; The Alaskan Way Viaduct, Seattle
To the 21st-century American, the idea of razing homes to make room for more roads may seem inconceivable, or at least dated. Our metropolises might be strangled with congestion, but you'd be hard-pressed to find a traffic engineer or highway designer who thinks more urban expressways are the solution. That wasn't always the case.
In the immediate post-war years, massive highway projects reshaped vast sections of the urban landscape. In New York, whole neighborhoods disappeared, and more than 5000 families were forced to move when master builder Robert Moses ran the 8.3-mile Cross-Bronx Expressway, a vital link in his vision for a massive network of urban expressways, through a densely populated segment of the Bronx. In the years after 95 divided the Bronx, the neighborhoods to the south, cut off from normal street traffic flow and related commerce, quickly faded into the blighted, burned-out south Bronx of the 1960s.
Across America, similar projects floundered in the face of community protest. The so-called "highway revolts" of the 1960s and 1970s brought central urban expressway expansion to a halt. According to Steve Alpert, a highway engineer trainee with HNTB, who studied the lessons of the Cross-Bronx Expressway at MIT, "You still never see inner-city freeways being built anymore."
What you do see, though, is cities grappling with the legacy of old urban expressways. Seattle, for example, is currently considering a proposal to replace its Alaskan Way Viaduct. Built in the 1950s, the elevated, double-decked highway runs 2.2 miles along central Seattle's waterfront. "This has been the center of a great debate; why put a viaduct on the waterfront?" says Ron Paananen, who is the project administrator for the proposed replacement of the Viaduct.
"It's a barrier to Seattle reaching its world-class waterfront," Paananen says. Recognizing this, Washington's Department of Transportation wants to tear down the Alaskan Way Viaduct and replace it with a tunnel. "That would eliminate the grid obstruction and actually reconnect cross streets," Paananen says.
Lesson No. 2 ||| If You Build It, They Will Come: So Plan for That
Interstate 25, The Valley Highway, Denver
(Photo by jared/Flickr)
The Offenders: Interstate 25, The Valley Highway, Denver
Originally built between 1944 and 1948, the Valley Highway in Denver is one of the older segments of the Interstate Highway system. Freeways, though, tend not to age gracefully, and this particular stretch is no exception. When it was built Denver's population hovered around 600,000. Since then, it's quadrupled to 2.4 million. Now, 200,000 vehicles use the Valley Highway each day, and according to Steve Hersey, a traffic engineer with the Colorado Department of Transportation, certain sections of the road are "almost always backed up." One major contributor to the congestion is the spacing, or lack thereof, between I-25's interchanges.
"When you look at these older roads, typically what happens is you start out and you have decent spacing," Hersey says. "But as roadside areas develop, which they tend do when you build a freeway past them, and you start adding interchanges, that's when you get into trouble."
While many of the interchanges on the Valley Highway are ¾ or just ½ mile apart, standards of highway design typically call for a mile between interchanges. Anything less than one mile makes it difficult to effectively place signage and adequately warn drivers of upcoming exits. Drivers also have less time to react. All of this contributes to increased amounts of weaving and merging.
CONTINUED: Geology, Love and Shoulders >>>