The plan to build a second subway line serving Manhattan’s congested East Side has been on the city’s drawing board for eight decades. Now, having withstood financial crises and opposition by residents near the construction zone, the $4.45-billion first phase of the Second Avenue subway project is under way, with 7,200 ft of tunneling almost completed out of a total of 15,000 ft planned. And as crews begin freezing a 150-ft stretch of earth for the second tunnel, they also are trying to thaw the hearts and minds of opposition groups.
With the help of Rockaway, N.J.-based subcontractor Moretrench, a joint venture of Skanska, Schiavone and Shea (S3) has begun the approximately 10-week freezing operation on the east tunnel as part of its $393-million contract. By the time the 22-ft-dia tunnel-boring machine finishes its north-south excavation of the west tunnel and comes back out to the launch portal, the stretch will be ready for it, says Gary Almeraris, Skanska project executive. “As we mine through it, we will install an outer 7-in.-thick concrete liner in order to hold up the ground as it thaws and keep water out.” Once mining of that section is completed, the final concrete liner will be installed for both tunnels.