MARBLE FALLS — Since the old U.S. 281 bridge’s closing Feb. 12, demolition crews have worked to remove everything from it except the steel truss, or frame, and the piers in the lake holding it up.
Now the hours, minutes and seconds are winding down for the structure.
The remaining time until the March 17 implosion leading up to the 8 a.m. detonation — weather permitting — has been planned in detail by the Texas Department of Transportation, Archer Western Contractors, Omega Demolition and Engineered Explosives Services.
The time of the implosion was set so officials could see during daylight hours but also so traffic would be at a minimum. To help ensure emergency services aren’t interrupted that morning, the city will stage one or two ambulances and fire trucks south of the bridge.
While the use of explosives to demolish the bridge has raised concerns from citizens, officials have made assurances that the method is safe. TxDOT has received authorization from the Lower Colorado River Authority, the Texas Parks and Wildlife Department, the Texas Commission on Environmental Quality and the City of Marble Falls for the demolition.
Howard Lyons, a TxDOT engineer, told citizens and the Marble Falls City Council on March 5 the new 10,000-ton bridge will not feel any effects from the implosion.
“The forces we calculated are such that it’s very, very remote that a charge done properly is going to have any effect that the (new) bridge is going to feel at all,” Lyons said. “But we feel like the possibility (of damage) is so remote that if it was even in the probability of a lightning strike, we wouldn’t even be looking at this.”
Officials also said buildings near the bridge on each side of the lake should not suffer any damage. Seismic monitors will be placed to survey the effects of the blast on nearby structures.
The goal of the implosion is to use explosives to make cuts in the steel to separate the frame into pieces that fall straight down into the lake. The frame then will be cut into smaller pieces that can be picked from the lake by large cranes and taken to a local recycling plant. TxDOT officials have said the process saves 60-90 construction days.
The implosion countdown really picks up during the early morning hours of March 17. Once the explosives arrive at the structure a day or two before the implosion, they will be put in place and a guard will be at the structure on 24-hour surveillance.
Boats will not be allowed within 1,000 feet of the bridge for four hours before the explosion.
Traffic will be stopped and officials will ensure the site is safe before the blast. After detonation, inspectors will inspect the pier by foot and by boat for any signs of structural damage. Officials said that should only take 10 minutes until traffic is again opened.
“If we do find something, we won’t jeopardize anything to save 10 to 15 minutes,” TxDOT spokesperson Kelli Reyna said. “We would rather stop traffic for 30 minutes or an hour to check and make sure everything is OK. We will not take shortcuts.”
Once the all-clear is given and traffic resumes on the new structure, officials said the metal should be removed from the lake within six days. Another blast to finish demolition of the two piers in the lake will be scheduled before April 8. In early April, construction of the southbound bridge is scheduled to begin. The entire project is expected to be completed in the fall of 2014.