Last week, Governor Andrew Cuomo announced that the expected 15-month shutdown of the Canarsie Tunnel between Manhattan and Brooklyn will not happen.
Instead, the MTA will embark on a new plan with a new design with technology that has never been used in the United States,
“With this design, it would not be necessary to close the L train tunnel at all, which would be a phenomenal benefit to the people of New York City,” Cuomo said at a news conference last Thursday. “It would be a major, major breakthrough.”
Hurricane Sandy flooded the Canarsie tube with corrosive salt water in 2012, damaging parts of the tunnel and power cables within the structure. The MTA’s original plan was to remove all 32,000 feet of benchwall, conduits and cables, and rebuild the entire tunnel.
Though the contract was already awarded to Judlau Construction, and both the MTA and city’s Department of Transportation (DOT) spent years working on alternative travel plans for commuters, Cuomo decided to tour the tunnel last month with his own team of engineers.
According to the governor, the expert panel, led by the heads of both Columbia and Cornell’s engineering schools, determined that a new design could be used that would avert the shutdown of the L train.
“It was labor intensive because much of the benchwall had to be removed by hand,” Cuomo said, referring to the MTA’s first plan. “You’re taking out a cement structure attached to the lining of the tunnel.”
Mary Boyce, dean of Columbia Engineering, detailed the new plan. Instead of rebuilding the entire tunnel, the innovative approach would implement an entirely new power and control system.
They would suspend the new cables on the side of the tunnel, and abandon all of the old cables inside the benchwall.
This would allow engineers to decouple the power cables from the benchwall, while installing new low-smoke, zero-halogen and fireproof materials, Boyce said.
As for the crumbling benchwalls, Dean Lance Collins from Cornell’s engineering school said engineers will remove the damaged and unstable parts, fortify the weakened parts with reinforced polymer, and leave the stable parts alone. They would use ultrasound technology to figure out the status of the benchwall.
The next step would be to install “smart” fiber-optic sensor cables along the remaining benchwall to detect any shifts or cracks. A high-resolution monitor system will also be added.
“We’ll be able to know in advance if any section of the tunnel is showing signs of deterioration, and be able to head off more significant things that might happen,” Collins said.
The engineers also plan to increase tunnel resilience against future flooding by increasing the pump capacity, install a permanent generator for the pumps, and consider installing watertight submarine-style gates and sealing all openings on the L line from First Avenue to Bedford Avenue.
Finally, to enhance public safety, the new plan calls for a detailed evaluation of all controls, ongoing structural condition monitoring and enlisting an independent firm to monitor air quality.
“We’re leaving the tunnel safer than it was originally,” Collins said.
Acting MTA chairman Fernando Ferrer said the repairs would take between 15 to 20 months to complete, depending on how much benchwall needs to be removed. Work would only be done on night and weekends, and weekday and rush hour schedules will be unaffected.
Rather than shutting down the entire tunnel between Brooklyn and Manhattan, this plan would only require one tube to be closed at a time, allowing the second tube to be used for trains.
“It's innovative, creative and a sound plan,” Ferrer said. “Without a doubt this is a less invasive, more efficient approach to rebuilding the L train tunnel for the future, and it represents a huge win for our transit system and our customers.”
Though elected officials and transit advocates applauded the possibility of avoiding a harmful shutdown, they posed many questions about the timing and process of the governor’s last-minute announcement.
On Friday, Mayor Bill de Blasio said on WNYC’s “The Brian Lehrer Show” that while this is “wonderful news” to the people of Brooklyn and Manhattan, he believes the MTA has “real explaining here to do.”
“This is a little strange to me because it has gotten so much attention, so much energy, so much expense already –– years and years of effort –– and I want to know more,” he said. “I want to know for sure that this will work, but also why on earth wasn’t it considered previously if it’s out there.”
Assemblyman Joseph Lentol called for a full vetting of the new proposal so that the north Brooklyn community, which would’ve been largely impacted by the shutdown, will understand and feel comfortable with the plan.
“I call upon the MTA and the expert panel to come into my district and answer questions from riders and businesses here,” he said in a statement. “That’s the next most important step they must take.”
Congresswoman Carolyn Maloney said she wants to know the true duration of the project, mitigation efforts to help riders on nights and weekends, cost of the new plan, its feasibility and other regulatory hurdles.
She also expressed concern that the MTA still wants to begin the construction at the end of April, which she believes won’t be enough time to work out the pitfalls.
“Nights and weekends are when people come to patronize many businesses along the L train route, particularly in northern Brooklyn, where there is no alternative subway,” Maloney said. “I am concerned that a full closure nights and weekends without sufficient mitigation will hurt businesses severely.”
John Raskins, executive director of the Riders Alliance, said in a statement that riders are “skeptical” of Cuomo’s “last-minute Hail Mary idea cooked up over Christmas,” as opposed to the MTA plan that was created with years of extensive public input.
Raskins called for a public release of the governor’s proposal, as well as mitigation plans during construction.
“Actual transit professionals, who owe nothing to the governor or the MTA, should evaluate whether this is sound engineering or a political stunt that will ultimately leave riders in the lurch,” he said.