Option 1: Shutdown the L train for 1.5 years as they completely close the tunnel and make the repairs.
Option 2: Shutdown only half the tunnel at a time over 3 years. Trains will run every 12-15 minutes and would be able to handle about 1/5th of the current 225,000 L train riders per day.
From NY Times:
The agency has ruled out making repairs only during nights and weekends because the complex work could not be done in such a narrow window, said Veronique Hakim, the president of New York City Transit, which runs the subway and buses. Building a subway tunnel under the river, as some residents have suggested, would be expensive and take too much time, Ms. Hakim said.
Under either proposal, the authority might run extra buses over the Williamsburg Bridge and add ferry service between Manhattan and Brooklyn. Riders could be directed to other nearby subway routes, including the G and M lines, which would have additional trains to handle more passengers.
While neither option will be any fun at all, which would you prefer?