On Thursday though, Gov. Andrew Cuomo announced an unexpected reprieve, saying that engineers would use a new technology imported from Europe to fix the tunnel without having to close it entirely.
The original plan would have shut the whole tunnel, starting April 27, to repair damage from Hurricane Sandy’s floodwaters. Cuomo’s new plan would take about the same amount of time, but would keep full train service during weekdays and close one of the tunnel’s two tubes on nights and weekends.
The news sounded good to many Brooklyn residents who rely on the L line. But Cuomo’s announcement raised a barrage of questions: Would the new technology work? Has it really been effective elsewhere? Why did Cuomo wait until the last minute to do this? People also wondered how much the construction would cost, and what would happen to plans for alternate service.
Cuomo said the Metropolitan Transportation Authority, which runs the subway, would rely on a new design that does not require the heavy construction mandated by the old plan. He said that not fully closing the L train would be a “phenomenal benefit to the people of New York City.”
The authority’s acting chairman, Fernando Ferrer, said that the agency agreed with a panel of engineering experts who recommended the new design, and that it would adopt the plan. He said the work could take about 15 to 20 months and would likely start around April, near when the shutdown had been scheduled.
For months, subway officials have been preparing for the closing and planning alternate options for commuters, which would have included a significant expansion of bus service and adding bike lanes. When the shutdown was announced in 2016, the news prompted panic in Brooklyn over what it meant for real estate and local businesses to be choked off from Manhattan.
The panel had been convened by Cuomo, who called the new design a “major breakthrough” that had been used in Europe but had not been tried in the United States.
“What these people have designed is the first of its kind in the United States of America,” said the governor, who was joined by the panel members. “No rail system has used this approach before. So it really is, from their point of view, exciting.”
“I don’t know if you can tell,” Cuomo joked, “but these engineers are excited.”
The new plan means that the L train’s weekday rush-hour schedule would remain the same. Trains would run at night and on weekends, but wait times would be longer.
The subway tunnel itself was structurally sound, the governor said, but the problem that needed to be addressed was saltwater leaching into the tunnel and coming into contact with electrical components.
“Saltwater and electronics do not mix,” Cuomo said.
A key provision of the alternative plan eliminates the need to replace major portions of the bench wall, which runs along the side of the tunnel and houses electrical cables. The cables were corroded because of damage from Sandy, Cuomo said.
Instead, using what engineers referred to as a “racking system,” new cables would be mounted on one wall and wrapped in protective material. A new power and control system would be installed, and the old cables housed in the bench wall would no longer be needed.
Last month, Cuomo, who controls the subway, toured the L train tunnel with engineering experts to see if there was another way to undertake the repair work.
“If there’s a better way of doing it, they tell us there’s a better way of doing it,” Cuomo said at the time. “If there’s not a better way of doing it, they say that’s the best that it can be done.”
Officials said the new plan also included improvements to make the tunnel more resilient in the event of a storm similar to Sandy. Those modifications included sealing openings that allow water to enter the tracks between the First Avenue station in Manhattan and the Bedford Avenue station in Brooklyn. The tunnel would also be equipped with technology to monitor its structural integrity.
The transit agency initially said the shutdown would be 18 months and later shortened it to 15 months. Subway officials had considered two proposals: a shorter, full closing of the tunnel or a partial three-year shutdown that would have allowed some trains to run.
They chose the full closure in an effort to do it quickly and limit the inconvenience for riders.
This article originally appeared in The New York Times.