The MTA detailed the damage to the L train’s Canarsie Tube and offered two potential shutdown options to reporters on Wednesday ahead of Thursday night’s public hearing in Williamsburg.

On the table at the moment are two proposals. One would bring complete shutdown of service between the Eighth Avenue and Bedford Avenue stations that would last 18 months. Another would close one of the two L train tunnels at a time, offering extremely limited service between Brooklyn and Manhattan over the course of repairs that would take three years.

The repair work is absolutely necessary, according to MTA Chairman Tom Prendergast, who said he understands the impact these repairs will have on the 400,000 commuters who ride the L train each weekday.

“This by far the most impactful capital construction project we have ever had to do on the system,” Prendergast said.

The repairs are needed after Superstorm Sandy severely damaged components of the tube in 2012. Those damages to the Canarsie Tube were far more severe than any other of the MTA’s East River connections. The authority said it needs to install new tracks and third rails; reconstruct concrete duct banks; replace communication, power and signal cables; install a new tunnel lighting system and repair the tube’s concrete lining, among other repairs.

At Thursday’s public hearing, MTA officials will outline potential service supplements, like new regular and Select Bus Service tripping across town in Manhattan; shuttle service over the Williamsburg Bridge and increased service along the G, J and M lines to handle additional capacity. During construction, the MTA will take the opportunity to install wider staircases and elevators to the First Avenue and Bedford Avenue stations.

Tonight’s meeting will start at 7 p.m. at the New York State Armory at 355 Marcy Avenue in Brooklyn.

Prendergast said on Wednesday that the MTA will have to decide on a plan within the “next two or three months” in order to award construction contracts for the work in November. This will allow for construction to begin in 2019

“Whatever action we take, we want it to be a proactive action along planned lines so that we know what we’re doing and effectively communicate to people what we’re doing,” he said. “New Yorkers I’ve found to be very resilient.”