The looming L train shutdown may not be as long as expected.

The MTA said it will seek board approval to shorten the rehabilitation time to 15 months, down from 18.

The shutdown would begin in April 2019, rather than January 2019, and last until July 2020, the MTA said. For that time period, the Canarsie Tunnel between Manhattan and Brooklyn would be closed in order to make repairs to damage caused by superstorm Sandy in 2012.

The new contract would cost $477 million, which adds $15 million in incentives to complete the repairs faster.

The shutdown is expected to impact hundreds of thousands of commuters.

“We promised to do everything possible to mitigate the impact of this vital work on L-line riders,” Ronnie Hakim, the MTA’s interim executive director, said. “We’ve done just that by shortening the tunnel closure from 18 months to 15 months.”