By Candy Thomson, The Baltimore Sun
6:01 PM EDT, October 25, 2012
Rollaway bridges: Take two.
Crews will try again this weekend to replace the first of two bridges that span the Baltimore-Washington Parkway at Nursery Road — a gateway to the airport business district — by rolling the old bridge out and the new bridge in.
Closures and detours will be in effect Friday night through Sunday morning. The State Highway Administration urges motorists to use alternate north-south routes, such as Interstates 95 and 97.
The project will be postponed if heavy rain and high winds from a major storm approaching the area begin earlier than predicted, said Melinda Peters, SHA administrator.
Last weekend, the entire process was halted shortly after it began when the 300-ton bridge deck over the northbound parkway shifted on the giant high-tech transporter and could not be moved backward or forward. Four large cranes were brought to the site to lift the 60-year-old bridge back into place.
Engineers and contractors discovered that the two self-propelled transporters were too short and that the wooden braces supporting the weight of the bridge were too narrow, Peters said. The support system has been adjusted and additional bracing added.
Overnight Friday into Saturday, crews expect to unbolt the span, then the transporter will move it to the median. The next night, the transporter will pick up the new 500-ton span, which was built earlier this year in the median, and haul it into place.
This is the first time Maryland has used the "bolt and roll" method.
"With any construction, there are some bumps along the way," Peters said. "We came away from the weekend with lessons learned that can be used elsewhere in the country."
State officials chose this approach as part of the Federal Highway Administration's Highways for Life program, which encourages construction innovations. A handful of other states, such as Utah, have embraced bolt-and-roll, but it has not gained widespread acceptance on the East Coast.
About 85 highway engineers from around the region plan to watch the SHA operation this weekend.
Despite last weekend's difficulties, Peters said she is "still seeing the long-term advantage" of the method as a way to minimize detours and road closures and shave a year off construction time.
The schedule calls for crews to replace the southbound bridge next weekend. The SHA planned the project for the three-week period that combined two Ravens' away games and the bye week so as not to disrupt traffic.
Motorists going to Baltimore-Washington International Thurgood Marshall Airport from the east can use I-97 to Route 176 (Dorsey Road) and follow the Airport Loop signs. Drivers heading to the airport from the west should use I-95 to I-195 to the terminal.
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