A new plan to remove the remains of the old Tappan Zee Bridge in New York involves explosives to demolish the old span.
The old structure was scheduled to be dismantled by removing the bridge in sections. However, concerns about workers safety have been raised after cracks appeared in the old structure.
The new $4bn (£3.1bn), 5km long Mario M. Cuomo Bridge opened in September after fears that the old Tappan Zee bridge, which runs parallel to the new bridge, could collapse and damage it were allayed.
However, the Federal Highway Administration is still concerned about the soundness of the old bridge and is consequently revising its demolition plan.
“The east span is tilting and is structurally unsound,” a Tappan Zee Constructors (TZC) spokesperson said. “So workers can’t get on it — it’s unsafe for them.”
It is unclear what type of explosives will be used or how workers will place them on the old bridge’s remaining structure.
Before the new bridge was opened, TZC announced a flaw in one of the original bridge’s joints which meant the old structure was at risk of falling.
The demolition includes 302,200 tons of concrete, 46,790 tons of steel, 13,192 timber foundation piles, 2,000 precast deck panels, 196 piers, 30 circular caissons, 20 steel truss sections and eight rectangular caissons.
A Thruway Authority spokesperson added: “In the interest of the safety of our workers and the traveling public, Tappan Zee Constructors is reviewing alternative means and methods to remove the old Tappan Zee Bridge’s east anchor span.”
Tappan Zee Constructors, is a consortium of design, engineering, and construction firms, including Fluor, American Bridge, Granite Construction, Traylor Bros., HDR, Cowi, URS, and GZA.
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