By Joe P Hasler | Popularmechanics.com | August 24, 2010
Whiling away the hours in roadwork-induced stoppages, you might find yourself cursing the traffic engineers and highway designers responsible for your misery. You might praise them for finally doing something about that particularly sticky wicket of an interchange. And you might wonder to yourself, “If there was a perfect highway, what would it be like?” At least that’s what we wondered. So we found some of America’s worst examples of highway design, and talked to experts in the field to find out what it takes to build good roads.
LESSON NO. 1 ||| DON’T BULLDOZE HOUSES FOR ROADS
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
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.
LESSON NO. 3 ||| CONSIDER THE EARTH YOU BUILD ON: GEOLOGY MATTERS
The Offenders: Interstate 10, Louisiana; The Alaskan Way Viaduct, Seattle
Every year, Overdrive magazine, a trade publication for long-haul truckers, polls its readers to determine the state with the worst roads in the country. For a number of reasons, Louisiana is a fixture at the top of the list. As one driver told the magazine in 2008, Interstate 10, which runs east-west across the entire state, is “rougher than a corncob.” The truckers aren’t the only ones who have noticed.
“You know you’re here from the bumps,” says Richard Levinson, a travelling jazz musician who works out of New Orleans in the winter. “As soon as you hit Louisiana, even if it’s dark and you can’t see the signs, you can tell.”
One explanation for the rough and rumbling roads of Louisiana is the soft turf on which they are built. Speaking to Overdrive in 2008, Mark Lambert, then communications director for the Louisiana DOT, said “Over time, you get waves in the concrete as the loose soil shifts or sinks, and if you’re in a long wheelbase vehicle, that gets pretty bumpy. You’ll get a bump about every 50 feet.”
In Seattle, the issue isn’t soggy soil, but shifting plates. One major factor driving the efforts to replace the Alaskan Way Viaduct is that the stacked highway is no way engineered to withstand the magnitude of earthquake Seattle, smack-dab in the middle of the Cascadia Subduction Zone, is susceptible to experiencing. In fact, the current viaduct is built in the same style as the Cyprus Viaduct in San Francisco, which famously failed in the 1989 Lomo Prieta earthquake.
“Over the past few decades I think there’s been a dramatic increase in understanding these issues, and advancement in the building codes to address them.”
LESSON NO. 4 ||| EVEN THE LONELIEST HIGHWAYS NEED A LITTLE LOVE (AND AMENITIES)
The Offenders: Utah Route 95, The Bicentennial Highway
Of course, linking major cities isn’t the only role of the American highway. They also provide access to the remotest spots in the country. And it doesn’t get much more remote than Utah State Route 95, otherwise known as the Bicentennial Highway. Stretching 165 miles across the high red desert between Hanksville and Blanding, the Bicentennial Highway offers a unique lesson—even roads in the middle of nowhere require attention and amenities.
End to end, Route 95 can take four hours to drive, and there’s very little in between. Along the way there are no rest areas or commercial facilities. There’s no place to buy gas, get food or stop for repairs. The pit toilets at Natural Bridges National Monument represent one of the few signs of civilization.
Kevin Kitchen, a liaison with the Utah Department of Transportation who specializes in the state’s southeastern transportation issues, says the major concern with the Bicentennial Highway is how its relatively low rate traffic volume affects road conditions. As a main access road for Lake Powell and several national recreation areas, including Natural Bridges, traffic is mostly seasonal. Those who do drive it, Kitchen says, know what they’ve bargained for. “Many motorists traveling through this area of the state comment that they choose this route precisely because of the isolation and the ability to escape roadside amenities,” he says.
But while drivers may be able to abide pit toilets and no service stations, unusable roads are another matter, and one that Utah DOT treats with extreme vigilance.
“Most of our current design efforts focus on preserving the pavement due to the typically low traffic volume,” he says. “The remote location and high desert altitude can pose maintenance and construction challenges, primarily because of the cost of mobilization.”
LESSON NO. 5 ||| NEVER UNDERESTIMATE THE VALUE OF A SHOULDER
The Offenders: The Pulaski Skyway, Newark to Jersey City, New Jersey; The Valley Highway; The Cross-Bronx Expressway
Built between 1930 and 1932, and linking Manhattan, by way of the newly constructed Holland Tunnel, to the transcontinental Lincoln Highway, the 3-mile-long Pulaski Skyway was effectively the final section of America’s first superhighway. Unfortunately, it stands today as one of the earliest lessons of how not to build a highway.
For one thing, its design was inspired by steel truss deck rail bridges of the era, and was based on the railway design principles of Arthur Mellon Wellington, whose book, The Economic Theory of the Location of Railways, was first published in 1887. A central railway principle was keeping land-acquisition costs down by employing the narrowest possible right-of-way. Applied to the Pulaski Skyway, the result is inadequately narrow roadways. Its two 24-foot-wide road decks allow for just two 12-foot lanes of traffic—the minimum width allowed for highway lanes—leaving no space for a shoulder, and very little margin of error for the modern driver.
“The value of the shoulder was not fully understood in the early days of highway design,” says Steve Hersey, a Colorado DOT traffic designer. Now, road planners ideally look to have at least ten feet of shoulder on the side of a highway. One element of this is to give drivers a breakdown lane. But Hersey says that as the width of a shoulder shrinks it also affects how people drive.
“The issue is capacity,” Hersey says. “If you have a shoulder that’s smaller than 6 feet wide, and you’ve got a guard rail or barrier wall, that will impact operation. Drivers become nervous. They overreact and slow down. They weave. And all of these behaviors affect the capacity of the road.”
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