Bridges and Congestion
Adding further to the compelling need for bridge investment is the fact that the nation cannot fix its congestion problems without fixing its bridge problems.
Most of the nation’s traffic and the vast majority of its truck freight travel on the nation’s major routes—the Interstate Highway System, the National Highway System and the urban freeways. The Interstate Highway System alone carries an estimated 24.5 percent of all miles traveled on U.S. highways, even though it comprises about 1 percent of all public road miles.
In 2006, the Interstate Highway System turned 50, and it is showing its age. Its 46,747 miles carried an estimated 727 billion vehicle miles of travel in 2004. Between 1995 and 2004 annual travel on the Interstate Highway System grew by 2.8 percent, at the same time that the system was expanded by only one-half of one percent. As a result, congestion has significantly increased on the Interstate Highway system and its 55,315 bridges. Nearly 12 percent of the rural Interstate bridges and 21 percent of the urban Interstates bridges were considered “functionally obsolete,” which means they are too narrow for today’s traffic volumes.
The Texas Transportation Institute’s 2007 Annual Urban Mobility Report notes that annual hours of delay per traveler in major urban areas rose from 21 hours in 1982 to 43 in 1995 to 54 in 2005, an increase of 157 percent in 23 years. Between 2004 and 2005, delays increased 3 hours, showing how quickly we are being stymied in traffic.
Much of this delay occurs at interchanges—and much of the interchange improvement costs are a direct result of the bridges that separate and elevate the lanes of freeway traffic. It is this “grade separation” that lies at the heart of modern freeway design, freeway speed, freeway safety and freeway convenience. Interchanges are the first component of a freeway to become congested. The movements of merging, lane changing, and exiting cause traffic to slow down, conflict and become congested when volumes exceed design capacity.
In 2005, the FHWA Office of Transportation Policy Studies commissioned a study entitled, An Initial Assessment of Freight Bottlenecks on Highways. This report looked at the magnitude and costs of highway delays to the nation’s commerce. It noted that about 40 percent of all delays are caused by recurring congestion, while 60 percent are non-recurring, such as weather, accidents or construction. Using a conservative figure of $32.15 per hour for the value of truck delay costs, the study estimated that there is an annual cost of $7.8 billion a year from bottlenecks involving trucks. Nearly half of this total delay was attributable to interchanges, with the rest attributable to steep grades or signalized intersections on major arterial routes.
Interchange Bottlenecks Delay Commerce
The study found that the top 10 highway interchange bottlenecks cause an average of 1.5 million truck hours of delay each year. Of the top 227 bottlenecks, more than 170 of them result in more than 250,000 hours of delay annually. This delay is especially acute at international trade gateways and hubs, such as New York, Los Angeles, Chicago, Dallas-Fort Worth, Denver and Atlanta. The top ten in terms of annual hours of delay for trucks are listed in the following chart.
Top Ten Highway Interchanges That Cause Truck Delays
| Annual Hours | ||
| 1. | I-90 at I-290 in Buffalo | 1,661,900 |
| 2. | I-285 at I-85 in Atlanta | 1,641,200 |
| 3. | I-17 at I-10 in Phoenix | 1,608,500 |
| 4. | I-90 at I-290 in Chicago | 1,544,900 |
| 5. | San Bernardino Freeway | 1,522,800 |
| 6. | I-94 at I-90 in Chicago | 1,512,900 |
| 7. | I-285 at I-75 in Atlanta | 1,497,300 |
| 8. | SR 142 at SR 2 in Los Angeles | 1,489,400 |
| 9. | I-77 at Tyron Road in Charlotte | 1,487,100 |
| 10. | Long Beach Freeway | 1,380,000 |
Costs High for Major Bridge Replacement
Fixing these and other bottlenecks depends upon a massive reconstruction and expansion of freeway interchanges, ramps, overpasses and bridges. This work will require significant investments, far exceeding their original costs.
One recent example is the Woodrow Wilson Bridge on the I-95/I-495 beltway around Washington. This original bridge across the Potomac River was constructed with four lanes in 1961. The structure was planned to carry 75,000 vehicles daily within 20 years but exceeded that volume within its first eight years. The new bridge consists of 12 lanes, with eight of them as general purpose and the remainder as high-occupancy vehicle lanes. Because of its close proximity to adjacent interchanges, four nearby interchanges also needed to be reconstructed to flow into the wider bridge. The overall cost was projected to be $2.524 billion.
Woodrow Wilson Bridge
Photo courtesy of Virginia Department of Transportation
Marquette Interchange construction.
Photo courtesy of Wisconsin Department of Transportation.
In Milwaukee, the Marquette Interchange handled nearly a third of all the state’s truck volume when measured by the value of shipments. The major routes in Wisconsin funnel through Milwaukee, the state’s largest city, and down into Chicago. The interchange of I-94, I-43, and I-794 carried a disproportionate share of the state’s traffic and truck volumes, with daily volumes exceeding 300,000 vehicles daily. To separate these movements, add interchange capacity and alleviate congested ramps, a much more complex four-level interchange was necessary at a total cost of $810 million. The original interchange built in 1968 cost $33 million.
Oakland Bay Bridge allows for greater volumes of traffic.
Rendering of the proposed Downtown Louisville Bridge and proposed East End Louisville Bridge,
between Kentucky and southern Indiana
Photo courtesy of Kentucky Department of Transportation
In Oakland, California, the Oakland Bay Bridge connecting with San Francisco actually was a complex network of bridges and a tunnel originally built for $77 million in 1936. Today, more than 270,000 vehicles per day use the route, which carries Interstate 80. Because of a much larger structure, the need for seismic protections, and other reasons, the new main span was bid at $1.43 billion. Construction currently is under way.
In Louisville, Kentucky, two new bridges across the Ohio River into Indiana have been estimated at $4.1 billion and will take until 2024 to complete, according to current schedules. Upstream in Cincinnati, the Brent Spence Bridge carries both I-71 and I-75 over the Ohio River between Cincinnati and northern Kentucky. Originally built in two levels with three lanes in each direction, the new bridge will need to have at least five additional lanes in each direction. The costs are estimated between $2 billion and $3 billion depending upon the alternative chosen.
Summary
The nation’s bridges have become chokepoints on the country’s freeway system, particularly at interchanges and major river crossings. The staggering costs of the new bridges and their related interchanges dwarf original construction costs. Many major U.S. cities that want to build new structures are at a loss as to how to raise the massive amounts necessary for their construction.
Bridges Move People:
Washington State: Sam’s Cafe—Cut Off from Its Customers
Tae Jung Kim, Min Kim, and Soo Jin Kim own Sam’s Café on the Tacoma Tideflats. The Murray Morgan Bridge (background) is closed to vehicle traffic, keeping many potential customers from dining at Sam’s.
The hectic lunch hour at Sam’s Cafe lasts only about 30 minutes now that the Murray Morgan Bridge is closed to vehicle traffic.
“We lost our regular customers from downtown (Tacoma),” said Soon Jin Kim, co-owner of the little burger joint on the wrong side of the bridge.
The Washington State Department of Transportation closed the 1911 bridge in October 2007 due to safety concerns.
On one side of the bridge is a bustling downtown, thousands of workers, residents, and potential Sam’s Cafe patrons. On the other side, known as the Tideflats, are Port of Tacoma businesses and Sam’s Cafe.
It wouldn’t be accurate to describe the Port area as desolate, but it’s certainly isolated.
“They don’t want to drive around to get to us,” Kim said of downtown residents and workers. That’s because a restaurant that is a stone’s throw from the city center is now a 10- to 15-minute drive.
“It’s inconvenient,” she said, “and gas prices are so high.”
Although the bridge closure has cost Sam’s Cafe some customers, Kim said there’s only been a slight decline in business. Fortunately, Kim said, more employees of Tideflats businesses and the Port of Tacoma are eating at Sam’s because they, too, don’t want to drive around to get downtown.
“Thank God,” she said.
Kim says skyrocketing gas prices and a weak economy are likely to hurt her bottom line as much as the bridge closure.
“All small businesses are hurting,” Kim said. “Hopefully, maybe it will get better.”
