By using fiber-reinforced polymer (FRP), the New York Metropolitan Transit Authority (MTA) will cut out 99% of demolition initially planned in the Canarsie Tunnel serving the L train between Manhattan and Brooklyn, which was flooded by Hurricane Sandy.
Hurricane Sandy inundated the Canarsie Tunnel with saltwater, and the cabling and power infrastructure, housed in the bench wall, were severely corroded. Emergency repairs were completed, but to return the tunnel to full strength, an overhaul is needed.
The MTA’s original plans included deconstructing the entire bench wall. Instead, after Governor Cuomo consulted with the deans of engineering schools at Columbia and Cornell universities, a progressive plan was designed to hang the cables on the tunnel’s walls and cover impacted areas of the bench wall with an FRP casing. MTA officials discovered a better long-term plan to cover the entire bench wall with the FRP casing instead of just bandaging the distressed areas. Crews will now demolish just 1% of the water-damaged structure and will cover the rest.
Andrew Smyth, an engineering professor at Columbia University and consultant on the project, explained, “Instead of an FRP wrap, it’s going to be an FRP shell. It’s slightly faster to apply because they can prefabricate the encasements.”
Another positive result of the project is a significant decrease in the amount of silica dust released during concrete demolition, which can damage the lungs if inhaled at high concentrations.
MTA Chairman Pat Foye commented, “I think there are New Yorkers who are going to be at cocktail parties over the weekend or at barbecues, weather depending, and they’re going to be discussing the bench wall. There are going to be other people at PTA meetings or watching their kids on the playground discussing FRP.”