1% solution in L train repair
Put a ‘cast’ on broken parts of tunnel
MTA officials plan to take an “out of sight, out of mind” approach to the crumbling concrete bench wall that’s at the center of the upcoming L train project.
Crews will demolish just 1% of the aging, water-damaged structure during construction that’s set to begin April 26, and will simply cover up the rest.
The MTA originally planned to deconstruct the entire bench wall, which houses critical power and communication wires, after the Canarsie Tunnel serving the L train between Manhattan and Brooklyn was flooded during Hurricane Sandy.
But Gov. Cuomo in January “cancelled” the planned 15-month shutdown of the tunnel after consulting the deans of the engineering schools at Columbia and Cornell universities, who said only 40% of the structure needed to be ripped up.
Instead, the academics suggested hanging the cables on the tunnel’s walls, and slapping a fiber-reinforced polymer (FRP) casing over the failing bench wall.
Since then, MTA officials have discovered they can get away with slapping the fancy material over the entirety of the bench wall like a cast.
“Instead of an FRP wrap, it’s going to be an FRP shell,” said Andrew Smyth, an engineering professor at Columbia who consulted the MTA on the project. “It’s slightly faster to apply because they can prefabricate the encasements.”
Smyth added that the material has been used in “lots of other situations,” and is not considered to be a temporary fix.
“There couldn’t be any clearer proof that the Columbia and Cornell deans and their professors provided an incredible public service,” MTA Chairman Pat Foye said Wednesday.
MTA officials hope the change in plans will quash riders’ concerns over silica dust, which is kicked up during concrete demolition and can damage the lungs when inhaled at high concentrations.
Construction crews will still need to chip away at the tunnel’s walls in order to install the racks that will hold the wires, but the overall demolition involved in the project is down to 7% of the original plan, according to MTA Chief Development Officer Janno Lieber.
Even with the new bench wall plan, many of the details surrounding the L train project remain murky.