The MTA unveiled details on planned repair work looming in the L-train's East River tunnel on Friday.
The 1.4-mile tube took on 7 million gallons of saltwater during Hurricane Sandy, causing extensive damage.
The MTA says it's considering a full-time shutdown of the tube and is looking into adding entrances at the Bedford Avenue and First Avenue stops.
The agency says it plans to do community outreach for riders and will look into service alternatives.
It expects to begin any shutdowns of the Canarsie tube by the beginning of 2019.
Nearly 3 million commuters travel through the tunnel every day.