A JV of contractors Skanska, Schiavone and JF Shea are set to win the first tunnelling contract on the first phase of the Second Avenue Subway project in New York, T&TI has been told.

The ‘S3 Tunnel Constructors’ JV is the apparent low bidder for the package with a tender of US$337M to the Metropolitan Transportation Authority’s Capital Construction Company (MTACC). A single rival bid from the Dragados/Judlau JV – already busy on the CM09 contract for the East Side Access Project in the city – was for US$497M.

The client plans to award Contract No 1 by the end of this month or in early March, and anticipates construction commencing in early April. Contract duration is 40 months but an incentive structure will be in place to try to get the programme down to 37 months.

Contract No 1 involves building twin tubes below Second Avenue between 63rd St and 92nd St, with a 248m long TBM launch box sited at the northern end between 92nd St and 95th St.

The 6.75m diameter bores are to be driven to lengths of 1.5km and almost 2.4km, respectively, through competent gneiss and schist with pegmatite. A hard rock TBM will most likely be used, the client said, and design papers have previously indicated double-shielded machines as likely. The longer tunnel will run to the existing Broadway Line, linking up via a new station at 63rd St, while the shorter tube pulls up short of the station planned for 72nd St.

Over a third of the tunnels will be unlined through the future station caverns. Where lining is required, the contractor has the option to go for pre-cast segmental rings or insitu concrete lining.

The job also involves a cross passage/sump and two 9m diameter shafts to facilitate access to works for Contract No 4. That contract involves mining out the major station at 72nd St plus crossover caverns and building Track G4 to 63rd St, and it is due to be awarded in late 2008.

However, the next contract due to be awarded, Contract No 2 to build 96th St station, is scheduled for June 2008. The station will build out behind the TBM launch box.

Three other construction packages are planned for the metro project: the refurbishment and expansion of 63rd St station; creating a mined cavern to house 86th St station; and Contract No 6 for track, signals and communications.

The Federal Transportation Administration (FTA) approved the start of the final design last April. Concept design and preliminary engineering was started in 2001 by DMJM Harris-Arup JV.

Future phases of the Second Avenue Subway project will see the line’s twin tubes extended farther along the east side of Manhattan, to the north and south. MTACC was established in mid-2003 in a reorganisation of MTA to take forward capital projects.