How could the M.T.A. do this without a shutdown?

The Metropolitan Transportation Authority will keep both tunnels open during weekdays for full L train service and do its work on nights and weekends, shutting down only one tube at a time.

Trains will run in both directions, but that will result in long waits between trains — up to 15 and 20 minutes — during repair times. The authority still plans on running more G, M and 7 trains to handle passengers who are rerouted during the repairs.

When will this start?

If the board approves, the work would probably start at the end of April, which was when the shutdown was supposed to begin.

How long will it take?

Transit officials said it could take 15 to 20 months. The previously planned shutdown was supposed to take 15 months. The governor stopped short of guaranteeing that it would not go beyond 20 months.

“It’s a silly question, ‘am I going to promise on a construction project?’” he said.

Who will be most affected?

L-train riders who work nights and weekends, or those who play on nights and weekends.

A luxury ride share company that started just for the shutdown, The New L, said it would keep its wait list open, just in case the new plans didn’t work, and there was still a need for the $155-a-month service.

Construction and congestion on side streets in the East Village could be abated, sparing neighbors fumes from supplemental buses and asbestos in the debris removed from the tunnel.