A complete shutdown of the East River tunnel that carries the L train between Brooklyn and Manhattan should be avoided, the Manhattan borough president said Monday.

A full shutdown would allow repairs to the superstorm Sandy-damaged Canarsie tunnel to be done in 18 months, but doing it one tube at a time could take twice as long, officials have said.

Borough President Gale Brewer said in a letter to the Metropolitan Transportation Authority and the city that it should consider doing the work at night and on weekends.

“A complete closure of the Canarsie tube will likely force a discontinuation of all L-train service in Manhattan since continuing service would isolate Manhattan train from the Brooklyn rail yards where they need to undergo repairs and maintenance,” she wrote.

Metropolitan Transportation Authority employees use a pump train to remove seawater from the L train's tunnel under the East River on Nov. 5, 2012. The tunnel was flooded during the unprecedented 13-foot storm surge of superstorm Sandy. Photo Credit: MTA / Patrick Cashin

The L train connects with stations on 14 other subway lines as it crosses Manhattan, but it has no connecting rails to those lines or to a subway yard.

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A full shutdown of the tunnel would cause inconvenience and damage “that may rival that caused by the storm itself,” Brewer said.

An MTA spokesman said Monday that “service plans are still being developed and all options are being considered.”

The Canarsie tunnel is one of the eight subway tunnels that was flooded during Sandy in 2012.

About 225,000 weekday riders go between Brooklyn and Manhattan on the L train daily. The line’s total daily ridership is 300,000, according to the MTA.

Brewer also urged the city provide ferry service across the East River nights and weekends while the repairs are underway.