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Construction & Design

Work crews doing L of a job keeping tunnel job on track

The tunnel is being repaired without a full shut down of service

Governor Andrew M. Cuomo announced the first phase of the L Project tunnel rehabilitation is complete ahead of schedule and on budget.

With work on the first tube concluding after only five months, the entire Canarsie Tunnel Rehabilitation is now scheduled to be completed on budget in April 2020 — bringing construction to a close a full three months ahead of the 15- to 18-month projections.

Governor Cuomo and senior MTA leadership toured the completed Manhattan-bound tube on Sunday, reviewing the new construction methods used to avoid a complete shutdown and maintain regular train service for 90 percent of L customers.

“Today we saw up close what happens when you abandon the old ways of doing things and think outside the box – you get the work done better, faster and cheaper. And in this case you get a better and safer tunnel than before,” Governor Cuomo said.

“This project will ultimately be a case study for how the MTA needs to operate going forward, especially as they implement the upcoming historic capital plan that will completely modernize the entire system and deliver the 21st century transportation service worthy of New York. I again want to thank our academic partners who collaborated to develop these innovative techniques and I commend the new MTA leadership for their work so far.”

Janno Lieber, MTA Chief Development Officer and President of MTA Capital Construction, said, “The Governor has laid out a bold vision for the future of transportation in New York. And we know much of it comes down to execution. This milestone for the L Project’s tunnel rehabilitation is proof that we’re ready.

“We’ve already been using lessons learned to improve execution of this major project, and I’m looking forward to applying the same kind of collaborative and aggressive project management strategy to revolutionize the way all MTA capital projects get done.”

MTA CEO and Chairman Patrick J. Foye said, “The Governor should be commended for having the vision to think about this project differently and help set a superior plan for executing it, and Janno’s entire team deserves immense credit for working with a sense of urgency and purpose that have delivered the first part of this project much more rapidly than anticipated.

“We’ve done all this while maintaining service for hundreds of thousands of customers. Today is a good day for the MTA. We will take lessons from this work and implement them into Capital Plan projects in the new Capital Plan.”

In January of 2019, with a full L shutdown looming to repair damage from Superstorm Sandy, Governor Cuomo convened academic leaders – including the deans of the Cornell University and Columbia University engineering schools – to review the two L tubes and determine if the rehabilitation work could be completed in a more efficient manner.

Following their review, the academic team recommended new construction methods and technology that have been used in transit systems around the world and several industries, yet never before integrated in a similar project in the United States.

Once rehabilitation work began in April, these techniques allowed New York City Transit to continue to run subway service in the tunnel throughout construction so that regular weekday commutes for the bulk of L customers between Manhattan and Brooklyn were not disrupted, particularly during the busiest times of day. Prior to those recommendations, NYC Transit had planned to close the entire L train tunnel to demolish and reconstruct the tunnel’s infrastructure.

With the revised approach to the tunnel rehabilitation, the work now completed in the first tube includes:

New cable racking system and new fire-resistant cables: The rehabilitation plan uses a racking system to suspend fire-resistant cables on the side of the tunnel rather than buried inside a concrete bench wall. This method increases the overall resiliency of the tunnel as the cables are easier to maintain and upgrade, and are located higher in the tube, decreasing potential for damage from flooding. On the 7,110 linear feet of cable racks, 48,440 total feet of new cables have been successfully installed: communications, radio antenna, pump power and control, and fiber optic cables. Above the cable racks, 28,000 feet of new signal cables were installed. An additional 38,855 feet of other new cable was installed: tunnel lighting conduit, sound power phone, antenna and tunnel receptacle power.

New wall structure with industrial fiber-reinforced polymer (FRP): This material, used to carry heavy loads of bridges in transportation facilities worldwide, was used to create a new wall structure along the tunnel. The tube wall structure and the bench wall are two separate pieces of the overall L tunnel structure, with the tube wall remaining sound and only the bench wall damaged from Superstorm Sandy. The FRP material was used to create structured panels, which are installed to wrap around the damaged bench wall. This new approach created a permanent wall structure, while eliminating the need to remove existing concrete bench walls, saving time and reducing the amount of debris and demolition-related dust.

New tracks, including new plates and continuous welded rail: 6,305 track feet have been installed, including new track ties, using continuous welded rail. This rail allows trains to safely operate at faster speeds, reduces wear and tear of car equipment and lowers the associated maintenance costs. The traction power system was also replaced with new composite contact rail, new traction power negative return cable system and new traction power positive cable.

New discharge lines, pipes and controls: The pumping system has been upgraded to handle even greater flooding from potential natural disasters. The new system more than doubles the water pumping capacity and has a remote monitoring and control system. Approximately 3,415 linear feet of discharge pipe has been installed with nine new pump manifolds.

New fiber optic monitoring system is being calibrated: 7,000 feet of specialized hydro- and geo-sensing fiber optic cables have been installed in the first tube. The system is currently collecting baseline data so the system can be calibrated to properly monitor for potential movement of the inner and outer benchwalls. Once the same cables are installed and calibrated in the second tube, the system will automatically process and transmit data and any alerts directly to the NYCT rail control center. Regular inspections will continue while the calibration is happening.

Work on the remaining track tunnel, which carries Brooklyn-bound trains, will begin on Monday, September 30. The MTA will continue rigorous monitoring of L train service and air quality controls, and its ongoing customer information campaign, as the L Project moves forward. All alternate service plans in place for the first half of the project remain unchanged as work continues in the second tunnel.

Additional planned work for the L Project is also continuing outside of the tunnel rehabilitation.

This includes three new substations to power more L train service and new elevators at the Bedford Av and 1 Av stations. These projects remain on schedule, targeted for completion by November 2020.

Work also recently started for the L Project’s accessibility initiative at 14 St-6 Av station, new escalator at the 14 St-Union Sq. station, and station upgrades to select Brooklyn L stations.

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