The planned 15-month shutdown and $1-billion repair of a critical New York City subway tunnel—three years in the planning and with work underway—is not likely to happen after the eleventh hour intervention by Gov. Andrew Cuomo (D-NY) into the process, with new project details released by the academics who developed it and project engineer WSP USA.

But questions over the viability and scope of the new proposed plan for the L Train route, handed to the Metropolitan Transportation Authority and still unapproved by its board, may alter a $477-million construction contract that is already in force.

The plan, announced publicly by Gov. Cuomo on Jan. 3 and first communicated to MTA in early December, calls for changing from a full shutdown of the line’s Canarsie Tunnel under the East River and a total demolition and rebuild of the interior to a partial shutdown using construction methods that will leave much of the existing interior in place.

Big Project Shift

While the original plan called for the full demolition and rebuilding of concrete bench walls along the more than century-old tunnel’s bottom sides that house conduits for power and other cables, the newly proposed plan would abandon the deteriorating bench walls in place, in favor of installing new cables in a racking system that will be bolted to the tunnel’s concrete liner.

This scope change would allow for trains to run on a limited basis during weekdays, with shutdown limited to only nights and weekends, according to Cuomo.

Other components of the original plan, such as track replacement and construction of new electrical substations and above-ground station access would remain in the new scheme. “We’re still going to upgrade core elements of the tunnel,” said New York City Transit Authority President Andy Byford in a WNYC radio interview on Jan 9. 

With original project design by WSP USA finished and above-ground work largely complete, a 70-30 construction joint venture of Judlau and TC Electric were preparing for the April 27 closure of the two-track Canarsie Tunnel. The planned 15-month shutdown was expected to impact the commutes of 275,000 riders. 

Not clear is how the Judlau-TC Electric contract could be altered in value and scope. Company officials did not respond to an ENR query.

The extended closure had been sold for years as a necessary step. The tunnel was flooded with brackish water during Hurricane Sandy in 2012, damaging cables and concrete structures, and the plan was to demolish the interior down to its lining and fully rebuild it.

Century Old Tunnel

The construction contract, awarded in the spring of 2017, includes the demolition and repair of the tunnel’s 100-year-old concrete liner as well as bench walls that carry electrical and signal cables. Flooding during Sandy significantly damaged these bench walls in particular, with clear signs of deterioration outwardly visible.

A full shutdown was planned due to the extensive demolition required and the amount of debris and material that would have to move in and out of the tunnel.

A similar method was used successfully in restoring the Montague Tunnel, which carries the subway's R train below the East River and was also flooded during Sandy. That year-long project finished three months ahead of schedule, and shares many similarities with the original plan for the Canarsie Tunnel.

But at his Jan. 3 press conference, Cuomo announced he had sought outside consultation from engineering deans and other faculty at Columbia and Cornell Universities who recommended a “racking” system to place cables in the Canarsie Tunnel, obviating the need to demolish and replace the bench walls in the tunnel.

Tracks will still be replaced and aboveground station access will still be improved under the new plan, but the scope of work underground has changed drastically. 

The plan was devised in December, 2018 with some input from project designer WSP. 

Fast-Tracked Alternative

Transit chief Byford has said in recent interviews that his agency and the MTA were not consulted on the plan, reportedly pushed by Cuomo in response to supporters' upset at economic impacts from the L train shutdown, and is calling for a review of the new proposal by an outside firm that hasn’t worked on the project.

The abrupt change caused consternation among MTA staffers who had worked on the previous plan and other high-priority storm recovery fixes, particularly the Montague renovation, and were not consulted about the unusual step to have outsiders revamp an already under way approach, according to agency sources. 

"The project team was crushed," says one source within the MTA, who said the contractor had "huge momentum," and could possibly have finished Canarsie Tunnel work in 12 months.  He says the proposed new approach "will be simpler," but more weekend work would boost labor costs. 

It also prompted questions from MTA board members seeing the details for the first time.

At a hastily called MTA board meeting on Jan. 15, members said a needed outside review consultant would be selected by MTA senior management.

Execution of the revamped project also now switches to MTA's Capital Construction group, said agency officials. Byford's NYC Transit Authority had been heading the pre-construction effort on the tunnel project.

"This is a radical change. No one on the board can make a decision without proper advice," said one MTA board member. "If it takes longer, so be it."

Cable-Racking System

Under the new plan, cables will be strung along a wall-mounted racking system, similar to ones used in some new subway tunnel construction, such as the western extension of MTA’s No. 7 Line and modern subways around the world.

Roughly 60% of the deteriorating bench walls would be left in place, with 40% to be either demolished, encased in fiber-reinforced polymer panels or placed under observation. A fiber-optic line would be run through the tunnel with sensors in place to monitor displacement in both the bench walls and the racking system. 

Using a modern cable-racking system on an existing, century-old tunnel is a largely unproven approach, as engineers from WSP explained during the public board meeting.

The Canarsie Tunnel is comprised of a welded cast-iron tube with an unreinforced concrete liner that is about 9 in. to 10 in. thick. Anchor bolts for a racking system would require small-diameter penetrations of only 4 in., according to WSP Senior Vice President and structures expert Michael Abrahams, who briefed MTA board members at the meeting. The racking system would carry power cables that weight about 5 lb per ft, and other necessary lines that each weigh about 1 lb to 2 lb per ft.

“The concrete liner does not carry the weight of the earth and the water, that’s the cast iron,” explained Abrahams. “The concrete was added later. We’ll have small diameter holes of very limited depth in that concrete liner.”

But a source familiar with the MTA's efforts on the project told ENR: "They will do enough repair to make it stable, but it's not a good construction practice to leave assets in a tunnel in bad condition and no longer functioning. It will allow systems to run safely but I don’t know the longevity of this solution. Concrete can pop and a rack can lean if an attachment fails," which would require maintenance and monitoring. 

When the issue of silica-dust control related to drilling and demolishing concrete was raised during the Jan. 15 meeting, Warren Goodman, Judlau safety director, said that his team would work to contain silica dust and meet federal OSHA regulations.

Approach Rejected in 2014?

One objection raised to the project was aired in the New York Times on Jan. 15, related to project documents prepared by original tunnel project construction manager Jacobs Engineering during the planning phase that showed a potential plan to string cables along the concrete liner being rejected in 2014.

This concern was addressed at the hearing later in the day, with WSP Senior Vice President Jerry Jannetti calling the Times’ assertion that the new plan is close to the earlier plan “not true.”

He added that the new approach “is a very different plan, not similar to plans done earlier or reviewed. The idea of racking coupled with leaving the bench wall in place, with a fiber-optic line, is very different.” The new racking system would require 60% fewer anchor bolts than in the plan proposed in 2014, he explained.

As to the benefits of the new plan compared to the previous plan, WSP’s Abrahams did concede at the board briefing that “it certainly would have been advantageous for long-term service life to completely tear out the duct banks and completely replace them.”

When pressed by MTA board members, WSP’s Jannetti said the new approach “if maintained ... could last for decades.”

Mary Boyce, Columbia University engineering dean and a member of Cuomo's advisory panel, told a WNYC radio interviewer that racking cables “was a superior solution,” and challenged the idea that this is a "10-year Band-Aid," saying the plan is "a 40 to 50-year solution.” She added, "MTA and WSP have been highly responsive to new ideas. It shows [the agency] is open to innovation, to do what’s best for New Yorkers."

Another unresolved issue, however, is whether the drastic change in scope would jeopardize $500 million in federal Sandy recovery and resiliency funding the project received. Answering this question has been delayed due to the ongoing U.S. federal government shutdown, according to MTA.

The MTA board is set to vote on the new plan at its next official meeting on Jan. 24, but a decision then is not guaranteed.

No updated construction schedule for the tunnel repairs has been publicly released.