America's Most Dangerous Bridges
While there were no casualties and repairs are under way, the incident has drawn attention to the condition of aging bridges across the nation. And now that road-trip season is in full swing, we wanted to take a closer look.
Consider Boston’s Storrow Drive, a double-deck roadway abutting Back Bay. Although nearly 60,000 cars cross this bridge heading west daily, few drivers may realize the condition of what’s beneath their tires: the structure, which carries the road’s westbound lanes over the eastbound, has been deemed “entirely insufficient” based on an evaluation formula used by government bridge inspectors.
The Storrow bridge’s design flaws and corroding support beams make it one of many highly trafficked bridges in the nation to earn a low sufficiency rating—a score that indicates a bridge’s sufficiency to stay in service. While a bad rating doesn’t necessarily mean danger is imminent, when combined with high traffic volumes, it signals possible trouble for a bridge.
A majority of the nation’s dangerous bridges are found in the Northeast, including No. 2 Pulaski Skyway in New Jersey. The disparity can be partly blamed on local conditions, according to Brian Leshko, a bridge expert with HDR, a global engineering firm based in Omaha, NE: steel tends to corrode more quickly in humid climates, especially where salt is used to de-ice roads in the wintertime.
One thing these bridges have in common, whether in Oregon or Louisiana, is age. All are more than 45 years old, and they’ve got company nationwide. Many structures from the bridge-building boom of the 1950s were designed for a 50-year lifespan, Leshko says. “When you do the math, you can see why we are where we are.”
Although many insufficient bridges are undergoing major rehabilitation or replacement, such improvements require years of work, and in the meantime millions of cars still rely on them daily. William Ibbs, professor of civil engineering at UC Berkeley, points out that the risk is often a fiscal one: these troubled bridges are expensive to fix, yet left untended, they could be forced to close, costing the people and industries that use them time, money, and inconvenience.
As the nation’s infrastructure continues to age, more large-scale projects will be necessary to keep our bridges in safe working order, according to David Goldberg of advocacy group Transportation for America, which recently released a report claiming 1 in 9 bridges is deficient, affecting more than 260 million Americans daily.
“We’re going to see a wave of bridges that are going to need major overhaul or replacement,” Goldberg says. “That’s something we need to be ready for.”
Read on to find out if your travel plans cross any of America’s most troubled bridges.
The MethodologyWe analyzed 2012 data from the Federal Highway Administration for nearly 700,000 bridges, focusing on the subset with an average daily traffic volume (ADT) of more than 50,000 vehicles. We ranked those bridges according to their 2012 sufficiency rating (SR): a percentage from 0 (worst) to 100 (best), which is determined by a Federal Highway Administration formula that factors in a bridge’s structural adequacy, safety, serviceability for modern use, and essentiality to the public. As civil engineer William Ibbs put it, “Those two variables are the standard measures we use for assessing bridge risk.” The resulting list reveals America’s high-traffic bridges with the worst sufficiency ratings (after removing 11 that are closed or have substantial improvements either completed or expected to be completed in the next year).
No. 1 Storrow Drive WB over Storrow Drive EB (Storrow Drive Tunnel), Boston
This double-deck roadway abutting Back Bay has been a headache practically since it opened in 1951. The problem: the pavement of the upper deck is too thick, straining the corroding steel beams that support the structure from underneath. Numerous rounds of costly interim repairs (most recently in 2012–13) have kept the artery open, but they’re merely stopgaps to extend its life through 2018 while longer-term solutions are weighed.
No. 2 (tie) U.S. Route 1/9 over Passaic River/NJ Turnpike (Pulaski Skyway), Newark, NJ
Herbert Hoover was president when this 3 ½-mile-long steel structure was completed, at which time its estimated traffic volume was 5,500 vehicles per day. Eighty years later, its capacity demands have increased more than tenfold, and its structural steel and concrete are rusting. A $1 billion rehabilitation under way now through 2016 should address these and other concerns throughout the length of the Skyway, including this 550-foot section that crosses 135 feet above the Passaic River.
No. 2 (tie) U.S. Route 1/9 over Hackensack River (Pulaski Skyway), South Kearny/Jersey City, NJ
The Skyway’s other 550-foot river crossing will also benefit from the $1 billion rehab, which includes a deck replacement, repairs to its concrete and steel supports, and an enhanced ability to handle seismic events. The repairs will close the Skyway to northbound traffic for 24 months starting in 2014, but southbound traffic will remain on the bridge during construction.
No. 4 NY Route 907C (Belt Parkway) Mill Basin Bridge, Brooklyn, NY
Opened in 1940, this Brooklyn span is the only drawbridge on New York’s Belt Parkway. Its outdated design has led to frustrations, including a major traffic jam caused in July 2012 when the bridge became stuck in the up position for more than an hour. Construction is just beginning on a new, 60-foot-tall fixed bridge to replace the Mill Basin Bridge; cars will continue to use the old structure until the new one is complete in 2017.
No. 5 NY Route 987D (Saw Mill River Parkway) over NY Route 907K (Cross County Parkway), Yonkers, NY
In a May 2011 inspection, this 1940 concrete bridge scored the lowest possible rating for its structural evaluation—an appraisal of its overall condition—that is permitted for a bridge that remains open to traffic. The Federal Highway Administration defines a structural evaluation score of 2 as “requiring high priority of replacement,” as compared to a bridge built to current standards.
No. 6 SR 520 over Lake Washington, Seattle
At nearly 1½ miles long, this span across the 200-foot depths of Lake Washington is the longest floating bridge in the world. But time has taken a toll on the 50-year-old engineering marvel: crews have repaired 30,000 feet of cracks in its concrete pontoons, and its design makes it susceptible to closure during windstorms. A wider, stronger replacement—which will be the world’s new longest floating bridge when it opens in 2015—is currently under construction.
No. 7 1-10 Calcasieu River Bridge, Lake Charles, LA
While the arching profile of this cantilever bridge may be aesthetically pleasing, its steep grades have been cited as a traffic concern, especially given the high volume of trucks the bridge carries along this major east-west corridor. Proposals to replace the 60-year-old structure have been discussed for more than a decade, but so far improvements have been limited to repairs and maintenance, including a $5.7 million project in 2012 to remove rust and replace damaged rivets.
No. 8 NJ Route 21 SB Viaduct over NJ Route 21 NB, Newark, NJ
Built in 1953, this section of overlapping highway has a list of flagged structural elements that includes an aging concrete deck and steel beams in need of repair. Plans are in the works to make the necessary improvements, but the project, now in the bidding stages, likely won’t see completion until late 2016.
No. 9 NY Route 907C (Belt Parkway) Gerritsen Inlet Bridge, Brooklyn, NY
Another historic Belt Parkway bridge, opened a year before No. 4 Mill Basin, this nine-span structure passes through the environmentally sensitive Gateway National Recreation Area. The rusting steel bridge will be replaced with a three-span version mimicking the historic character of the original and scheduled for completion in 2016.
No. 10 Coburg Road over Willamette River (Ferry Street Bridge), Eugene, OR
Eligible for the National Register of Historic Places, this 1950 steel truss bridge was reconstructed in 1999. However, like many of the compromised bridges on the list, the Ferry Street Bridge’s design is considered “fracture critical,” meaning that it lacks a redundancy among its components, which makes the bridge susceptible to partial or total collapse should any one of those components fail.
No. 11 (tie) NY Route 907L (FDR Drive) over 34th Street, New York
This concrete-and-steel structure paralleling the East River in Midtown hasn’t been reconstructed since it was built in 1966. As a fracture-critical bridge, its vital features require inspection every 12 months—instead of the more standard two years—and a July 2011 inspection recommended the bridge undergo a deck rehabilitation. The New York City Transportation Coordinating Committee endorsed a proposed $230 million replacement in early 2013, but construction has yet to begin.
No. 11 (tie) MA Route 145 (Revere Beach Parkway) over MBTA and railroad, Boston
The oldest member of the list, this bridge in the northern suburb of Revere opened in 1903. Unable to handle modern demands, the bridge is closed to truck traffic. A 2013 state report found that: “As conditions worsen, the bridge will pose serious and unacceptable safety hazards to the traveling public and would place intolerable restrictions on transport and travel.” A proposed $9.1 million bridge replacement is now in the planning and review phases.
No. 13 I-84 WB over Amtrak, parking, local roads (Aetna Viaduct), Hartford, CT
This stretch of elevated highway snaking for two-thirds of a mile through the city center has its share of detractors, some of whom advocate removing it entirely to reunite the downtown neighborhoods it bisects. A $22.3 million rehabilitation project in 2009–10 addressed immediate issues including repairs to its structural steel and concrete decks, but longer-term solutions are currently unfunded through 2014.
No. 14 NY Route 907L (FDR Drive) over Avenue C Bridge, New York
Located on the FDR Drive less than a mile south of bridge No. 11 on the list, this 1947 structure also has fracture-critical features that require inspection every year. The six-lane bridge was reconstructed in 1998, but more recent inspections recommend it be widened and its concrete deck be rehabilitated or replaced.
No. 15 I-5 over the Columbia River SB, Portland, OR/Vancouver, WA
An average of one car accident per day occurs on the five-mile segment of I-5 surrounding this drawbridge, and crashes increase by three to four times when traffic must stop for the bridge to lift open. A project to create a five-lane replacement bridge was proposed about a decade ago, but became politically contentious and failed to secure necessary funding in June 2013.
No. 16 I-5 over the Columbia River NB, Portland, OR/Vancouver, WA
Before the No. 15 southbound span was built in 1958, this 1917-era structure carried both directions of traffic across the Columbia. It, too, was to be replaced as part of a proposed $2 billion project that was called off due to a lack of funding in June 2013, after millions had already been spent in planning.
No. 17 I-84 EB over Amtrak, parking, local roads (Aetna Viaduct), Hartford, CT
In August 2012, local news reported that a three-foot chunk of concrete came loose from a joint in this section of elevated interstate, causing a vehicle to flip onto its side when the driver swerved to avoid it. As with the westbound direction of the same maligned stretch of highway, repairs have kept the nearly 50-year-old bridge open, but more permanent improvements are currently unfunded through 2014.
No. 18 CA Route 99 SB over Stanislaus River, San Joaquin County, CA
A February 2012 inspection found this concrete arch bridge’s superstructure—the portion of the bridge that supports the deck—to be in critical condition, indicating deterioration of primary structural elements. Replacement was recommended, and the bridge was included in a study for the reconstruction of a nearby interchange, but the proposed plan stops short of the river crossing.
No. 19 NY Route 907P (Harlem River Drive) over ramp to NB Harlem River Drive, New York
Built in 1958, this six-lane bridge adjacent to the Harlem River scored a structural evaluation rating of 2 in a June 2011 inspection, the lowest possible for a bridge that remains open. Its fracture-critical elements require inspection every 12 months, and it has been recommended for replacement. Plans for a new bridge are underway, with construction expected to last from late spring 2014 through spring 2017.
No. 20 I-495 NB over abandoned railroad, Amesbury, MA
This three-lane bridge built in 1964 was given a “poor” rating for both its deck and its superstructure, which supports the precast concrete deck that cars travel over. Two arched replacement bridges are in the design phase for this and its matching span in the opposite direction, but construction won’t begin until 2015.