Remaking an entrance

Aug. 6, 2008

By lowering a section of the Frederick Douglass Memorial Bridge, engineers have raised the level of development and cohesiveness of the neighborhood on the northern bank of the Anacostia River near the new ballpark of the Washington Nationals. Rehabilitating the bridge (also known as the South Capitol Street Bridge) is part of a major redevelopment of the South Capitol Street Corridor to improve access to Washington, D.C., and improve the streetscape with better pedestrian walkways and environmentally sensitive lighting.

By lowering a section of the Frederick Douglass Memorial Bridge, engineers have raised the level of development and cohesiveness of the neighborhood on the northern bank of the Anacostia River near the new ballpark of the Washington Nationals. Rehabilitating the bridge (also known as the South Capitol Street Bridge) is part of a major redevelopment of the South Capitol Street Corridor to improve access to Washington, D.C., and improve the streetscape with better pedestrian walkways and environmentally sensitive lighting.

Instead of cruising right over the Anacostia waterfront, motorists driving north on the Douglass Bridge now descend to an at-grade intersection that is integrating into the neighborhood at Potomac Avenue and South Capitol Street. As motorists reach the end of the bridge, they have a view of the entrance to the Washington Nationals’ ballpark.

The $27 million renovation of the bridge had to be coordinated with the placement and scheduled opening of the ballpark.

“We’d originally looked at doing temporary off-ramps and then demolishing the current ramp in place,” Susannah Kerr Adler, project manager for Parsons Brinckerhoff, told Roads & Bridges, but the proposed off-ramp was in the middle of where the ballpark was under construction.

“And then the timing of the ballpark happened more quickly than we were anticipating, and the bridge rehab job started a little bit later than we thought it would,” said Adler, so PB had to look for a way to cut nine to 10 months out of the bridge renovation schedule.

“Actually it was a challenge that we all were very excited about,” said Adler. “We basically had constructability workshops and looked at how we would construct this, looked at the different mechanisms for both doing the bridge rehab as well as the new interchange and all the streets surrounding the ballpark, came up with several options, and the one that had the biggest effect was this construction technique for lowering part of the bridge in place instead of building a temporary ramp.”

Soft landing

The plan was to begin the bridge off-ramp at the first pier after the river and lower it from there to grade level at Potomac Avenue. Amman & Whitney coordinated about 30 hydraulic jacks to keep the 200-ft section together and slowly lower it to its new position. Then the transition from the bridge to the new ramp was made gradual so as not to jolt motorists crossing the bridge.

The remainder of the old, elevated bridge structure was demolished and replaced with an at-grade street.

Other major tasks in the Douglass Bridge rehab included repaving the driving surface and repainting the steel components of the structure.

Lowering the bridge section required closing the bridge for two months in July and August 2007. During the closure, Parsons Brinckerhoff and the local agencies, such as the District of Columbia Department of Transportation (DDOT), the Washington Metropolitan Area Transit Authority and the Maryland Transportation Authority, provided incentives for commuters to use transit.

“We used a program that we had used on the Woodrow Wilson Bridge, called Bridge Bucks,” said Adler. Commuters entering or leaving the district for work could receive about $50 a month to apply to the cost of public transit or carpooling. The program focused on commuters who were going to work in the district or living in the district and going to a job outside.

“That was incredibly successful,” said Adler. “I think it was sold out the whole time period.”

In addition to Bridge Bucks, the bridge renovation team worked closely with local and regional newspapers, radio news crews and TV newscasters to let the public know when the bridge would be closed partially (on several weekends) or completely. They also talked with neighborhood associations about what they wanted to do and why.

Another disruption to the 76,000-vehicle daily bridge traffic was the repaving work. The first task, performed by Lane Construction, was to mill off the old asphalt. Then came the task of repairing the base for new asphalt. There were several areas that needed “half-depth” repairs, according to Ardeshir Nafici, deputy chief engineer in charge of design and construction for DDOT.

“In many locations on this bridge, we had half-depth repair, which normally we go about an inch below the top mat of rebar,” Nafici told Roads & Bridges. The rebar is about 2 in. below the surface of the concrete bridge deck. They break out the old concrete, repair or replace any damaged rebar and pour new concrete to bond to the old.

There is a second layer of rebar below. For full-depth repair, which was needed in a small number of areas, the contractor removed the entire depth of the deck, repaired or replaced any damaged rebar and poured new concrete.

“After we did that,” Nafici said, “we cleaned the surface and we put asphalt on top.”

Renewed surfaces

The new asphalt laid on the five-lane bridge was a Superpave mix with an aggregate size selected to reduce noise, according to Nafici. Fort Myer Co. laid the asphalt.

“The size of sand and gravel that we are using is different,” said Nafici. “This is the new design that most of DDOT are using for their asphalt.”

The other major job on the bridge was painting. All of the steel elements of the bridge had to be shot-blasted clean and repainted. To protect the environment from lead-containing dust, the contractor built a pressurized container around the section of the bridge to be cleaned. The negative air pressure inside the containment kept the dust from escaping. Nafici said the bridge was cleaned to meet the SP10 standard.

“SP10 means that the steel structure has to be really and truly clean like brand-new steel that you get from a plant,” said Nafici. “After that, we check the steel. We repair those areas that need to be repaired. In this particular case, we had a lot of areas that, over the years of being exposed to weather, had a lot of section loss.”

All told, they blasted 70 tons of rust off of the bridge and put back about 100,000 lb of new steel.

The Frederick Douglass Memorial Bridge reopened to traffic on Aug. 29, 2007. The overall renovation project was completed in time for the opening of the Washington Nationals’ season in April 2008.

In keeping with the spirit of turning South Capitol Street into an aesthetically pleasing urban boulevard, the bridge received decorative railings and more environmentally sensitive and decorative lighting. The new LED lights require less power to operate and minimize light pollution.

Lighting, please

PB designed new walking paths for pedestrians and bikers and used the new lighting to ensure that the walkways were properly lit. Adler said the new walkways “create a more aesthetically pleasing experience crossing the bridge” and also give walkers and bikers a greater “sense that you are secure and safe walking across it.”

Neighborhood traffic did increase significantly with the opening of the new ballpark, Adler said, but more traffic did not mean more traffic problems. The development plan called for repaving the area streets to their original, approved widths. The streets now have greater capacity with sidewalks, curbs and gutters.

The reason for the renovation of the Douglass Bridge was that it had reached the end of its planned life span. There was no doubt about its safety, said Adler, but renovations were needed to ensure its current performance for another 10-20 years while a replacement bridge is finished.

A study conducted a couple of years ago recommended building a replacement bridge.

“We’ve defined its location and alignment and also have narrowed it down to some bridge types,” said Adler, who also is a vice president at Parsons Brinckerhoff, which is in charge of engineering the larger South Capitol Street Corridor redevelopment. “Over the next six to 12 months, they will be selecting a specific bridge.”

The final design and construction of the replacement bridge depends on when funding becomes available.

The new bridge alignment will be a little to the west of the current bridge, as planned, but will end up at the intersection of South Capitol Street and Potomac Avenue, like the current bridge. According to the plan, drivers over the new bridge should have an excellent view of the nation’s capitol building as they enter the nation’s capital city.

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