Tag Archives: Rehabilitation

Corrosion Work on George Washington Bridge will take 10 years

Peter Zipf sounds more cardiologist than civil engineer when he talks about subjecting the George Washington Bridge to the equivalent of the classic battery of tests for heart disease and finding the first signs of plaque.

“It really is a little like giving somebody an EKG and checking their cholesterol levels,” said Zipf, the Port Authority’s chief engineer. “There are certain things you know you have to watch for, to catch them before they go too far.”

And chief among those certain things, as a bridge ages, is the corrosion that can sap the strength of its steel.

“Moisture is the big culprit,’” continued Zipf. “You have to constantly monitor the amount of corrosion and the rate of deterioration, and then determine when to intervene.”

The GWB’s test results have spurred the Port to intervene now and undertake the biggest rehabilitation in the 81-year history of the world’s busiest bridge. When the work is completed in 2022 – yes, 10 years from now – the Port will have spent $1.5 billion, a piffle in comparison to the $6-billion-to-$8-billion that it would cost to build the GWB today.

The centerpiece of this your-tolls-at-work program will be the first-ever replacement of the GWB’s suspender ropes, all 592 of them. The ropes, vertical bundles of woven steel wire that attach to the four main cables and support the deck, will be replaced a couple or three at a time to keep the 600,000-ton bridge on an even keel.

To assist, the Port, fittingly, has hired Ammann & Whitney, the consulting engineering firm founded by Othmar Ammann, the man who designed and built the GWB and five other suspension bridges in the city.

The Port will also rehabilitate the upper level’s deck (work already in progress), remove the lower level’s original, and failing, lead paint, rebuild the 177th and 178th Street ramps as well as the multiple ramps to the GWB bus station and repair the Center and Lemoine Avenue bridges.

“The bridge can withstand this extreme work because it’s very robust in terms of strength – remember it was built to handle rail,” explained Zipf. “So that extra strength becomes a safety factor that gives the bridge the tolerance for rehabilitation.”
(Careful readers will recall the Thruway Authority will spend more to build the new Tappan Zee Bridge strong enough to support rail – or serious rehabilitation in the next century, if rail is never added.)

Does any or all of this mean the bridge-and-tunnel crowd is doomed to construction delays at the GWB for 10 years?
“In all of our work, through design, staging of construction and so on, we strive to minimize the impact on traffic,” pledged Zipf. “We’ll only close a lane during off-hours or at night, so if you cross the bridge at rush hour, you aren’t going to be aware that anything’s going on.”

…For 10 years.


Verrazano-Narrows Bridge paint job will extend span’s lifespan

It’s not going to be Vincent Van Gogh’s “Starry Night,” but the $19 million paint job on the Verrazano-Narrows Bridge will put corrosion in check and extend the span’s life.

The scheduled two-year project began late in 2010, but workers for the contractor just started stripping the old lead-based paint in July, said MTA spokeswoman Judie Glave.

The work also includes repairing and rehabilitating corroded steel, then finally applying three fresh coats of a special high performance paint designed for bridges to the interior and exterior of the tower legs on the Staten Island and Brooklyn sides,” Ms. Glave said.

Islanders might have noticed a wrapping around the bridge legs, which is a containment system comprised of tarps that will catch the lead paint chips safely to keep it out of the environment, Ms. Glave explained.

The collected paint chips are then disposed of in “strict accordance with New York State regulations,” Ms. Glave said.

The work was included in the current 2010-2014 capital budget and funded through toll collections and TBTA (Triborough Bridge and Tunnel Authority) bonds, not requiring any state or federal money, Ms. Glave said.

Barges positioned in the water near Staten Island’s bridge tower will allow workers to use abrasive blasting to strip away the old paint, and there will be no traffic impact from this project, Glave added.

“Regular attention to painting steel on bridges is critical to keeping them in a state of good repair and to provide a protective coating against corrosion,” Ms. Glave explained. “The Verrazano-Narrows is particularly susceptible to corrosion because of the wind patterns where it sits in the bay and the bridge’s exposure to harsh sea and salt air.”

Corrosion on the Verrazano varies depending on the area of the bridge and its exposure to the elements.

Some of the areas contractors will be working on are the original paint, while other parts were repainted in the late 1980s, Ms. Glave said.

In 2010, about 188,000 vehicles per day traversed the bridge, Glave added. 

SOURCE: http://www.silive.com/news/index.ssf/2011/08/v-n_bridge_paint_job_will_exte.html

Hunter Mill Road bridge to be replaced

The bridge carrying Hunter Mill Road over Difficult Run will be replaced with a temporary structure this month after a regular inspection found severe corrosion in the bridge beams.

The corrosion cannot be repaired, according to the Virginia Department of Transportation. A temporary truss bridge will be installed this month, requiring some lane closures on the two-lane road. VDOT hopes to construct a permanent replacement next summer.

The damaged bridge did not posed a risk to drivers, said Jennifer McCord, a VDOT spokeswoman.

“VDOT has chosen, however, to remove the bridge from service as quickly as possible —especially after considering the large number of users, including trucks, who travel on Hunter Mill Road and its vital role as a corridor in Fairfax County — to eliminate any chance that heavy traffic conditions would contribute to accelerated deterioration and pose a future safety risk,” she said.

VDOT also reduced the weight limit on the bridge as a precaution.

The temporary truss bridge will cost about $300,000 to install. The permanent bridge will cost about $3 million; VDOT does not have money set aside for it.

The bridge was last replaced in 1993 with a structure consisting of a timber deck and steel beams, a type of bridge that has a lifespan of about 20 years under normal conditions, McCord said.

That bridge was intended to be an interim replacement while the state developed plans for a new one. But that project was later canceled because of opposition from the community.

The Hunter Mill Road bridge has been rated structurally deficient since 2005, a term meaning a bridge needs more frequent inspections and is a candidate for future rehabilitation and replacement.

While there are dozens of bridges in the area rated structurally deficient, Northern Virginia has the best bridge ratings in the state, McCord said. About 4 percent of bridges here are classified as deficient, compared with more than 10 percent statewide.

“There are a small number of structures on more heavily traveled, two-lane secondary roads that are classified as structurally deficient,” McCord said. “For most of them, plans for replacement in the next several years are already in development, and if not, they are candidates for rehabilitation or replacement as funds become available.”

All such bridges receive regular inspections and maintenance, she added.

SOURCE: http://www.fairfaxtimes.com/article/20110805/NEWS/708059738/-1/hunter-mill-road-bridge-to-be-replaced&template=fairfaxTimes

Aging U.S. 2 trestle gets needed corrosion repairs

With thousands of vehicle trips daily, U.S. 2 gets needed repairs

EVERETT (WA) — Concrete is falling off in chunks, rebar is rusting and thousands of people drive over the westbound U.S. 2 trestle every day.

While the girders on the trestle’s underbelly have been slowly deteriorating for more than 20 years, state transportation officials say there’s no doubt the bridge is safe for drivers. Repairs are being made this summer and fall.

About 37,000 vehicles per day use the trestle in one direction or the other.

“There’s no problem with people driving on the structure,” said Chad Brown, project engineer for the trestle repair. “The structure is safe.”

Workers are restoring the exposed rebar, replacing the concrete on the girders and sealing them to keep them waterproof. The repairs are expected to preserve the girders on the now 43-year-old span until 2026 or longer. The $8 million project began earlier this month and is expected to be finished in the early fall.

The roadway on the trestle is built atop girders made of concrete and rebar, running lengthwise with the roadway, sitting atop crossbeams that in turn sit on pillars. The eastbound half of the trestle was built with timber in the 1930s and rebuilt in sections in the 1990s, according to the state. The westbound side was built in 1968.

By 1987, crumbling began to show on the concrete beams on the underbelly of the westbound structure, and the bridge was declared “structurally deficient.” The term is a federal designation meaning that a bridge has a part or parts that will eventually need to be repaired, not that it is unsafe, according to the state. Washington currently has 143 bridges in this category, including seven in Snohomish County.

Under the state’s routine inspection program, bridges are examined every two years. Some with more structural issues are put on a yearly schedule, and the trestle has been inspected every year since 2003.

The section currently being repaired was done four years after the other section because of funding issues and environmental regulations involved in working over Deadwater Slough, officials said.

The current repairs are being done in the same manner as in 2007. The bridge at the far west end of the trestle, over the Snohomish River, is newer and won’t be repaired in this cycle.

Engineers are confident the moisture has not further penetrated the beams. So far, the farthest into any beam that weak concrete has been found is a couple of inches.

Traffic on the westbound trestle will be shut down for up to 65 nights through early October for the concrete and carbon-fiber mesh work. These phases have to be done when there’s no traffic on the road so vibrations won’t prevent the concrete from setting properly or keep the mesh from bonding to the concrete, engineers said.

The trestle was closed for three nights on June 9, 14 and 16 while two sections were repaired. It’s possible the work will take less than the 65 nights. The next closure is planned for July 12.

If the girders are not repaired, beams and the rebar would continue to deteriorate, and longer closures would be needed, engineers said.

Nancy Singer, a spokeswoman for the Federal Highway Administration, said federal engineers say the work being done on the trestle appears to be appropriate.

“State departments of transportation are the owners and operators of infrastructure and are in a position to select the best approach to addressing the needs of a bridge,” she said in an email.

“The U.S. Route 2 project that calls for replacing old cracking concrete, removing corrosion from the steel frame, and reinforcing the girders on the underside of the viaduct seems to be based on sound and established approaches to bridge repair and rehabilitation.”

SOURCE: http://www.heraldnet.com/article/20110627/NEWS01/706279969