Paula Wallis, TunnelTalk

The Skanska/Traylor JV is the apparent low bidder for the 86^th Street Station cavern on the Second Avenue Subway Line in New York City. The JV's bid of early $302 million beat out four other joint ventures vying for the lucrative contract (Table 1). The low bid is roughly $800,000 below the Engineer's estimate of about $400 million.

The result adds to the JV's recent win in Washington DC, where it is awaiting award of the Blue Plains Tunnel for the multi-billion Potomac and Anacostia River CSO clean-up program for DC Water. The Second Avenue Subway contract includes excavation and finishing works of the 86th Street station as well as shafts and adits for the entrances, ancillaries and cross passages; demolition work in advance of entrances and ancillaries; and underpinning of existing buildings adjacent to the ancillaries and Entrance 1 (Fig 1). Construction could be impacted by the ongoing litigation over the location of the station's entrances.

Table 1. 86th St station bid result Skanska/Traylor $301,860,000 Conti/J.H. Reid $334,777,433 Shea/Kiewit/Schiavone $391,717,426 Barnard/Judlau $453,631,980 Granite/Yonkers/SK $460,443,000

Fig 1. Plan of Second Avenue Subway's 86^th Street station

Excavation of the cavern will proceed but the legal issues could impact the timeline when the demolition work and entrance scoping begins.

Meanwhile the Robbins hard rock TBM working on the project finished the first of its two running tunnel drives from 92^nd Street to 63^rd Street on February 4^th. "The best day on the first run was 114ft (35m), with an average of about 41ft/day (12.5m/day)," said Tom Peyton of Parsons Brinkerhoff and Project Director for Construction. "We decided, during the drive, to extend the tunnel by 2,200ft (670.5m) and on the extension average advance was about 49ft a day (15m/day)."

Peyton said the Robbins machine completed the roughly 7,200ft (2,195m) first drive with no major issues. The TBM is about 30 years old and was first used to excavate the MTA's 63^rd Street Tunnel in the late 1970s. It has been used on at least four other projects, most recently on the Fall River CSO Project in Massachusetts.

The TBM was disassembled and the trailing gear pulled back to 92^nd Street launch shaft. It was re-launched on March 21^st and is about 223ft (68m) into its parallel 7,800ft (2,377m) second drive, which includes a tight westerly curve into the existing 63^rd Street Station.

Second Avenue Subway Phase 1

The first 200ft of the drive was in frozen ground. Ground freezing, installed by specialist subcontractor Moretrench, was needed for safe launch of the TBM through weak water-bearing ground.

"The ground is as expected," said Peyton. "There are one or two additional faults and the typical Manhattan rock is very blocky, but no big surprises. Everyone is fairly optimistic that the second drive will be finished by the end of the year. In addition, the cast-in-place final lining is going to start in the west tunnel later this month."

Elsewhere on the project, Schiavone/Shea/Kiewit JV (SSK) was awarded the $447.2 million 72^nd Street station contract in October 2010, and is into construction of the contract's 69^th and 72^nd Streets shafts. Reconstruction of the 63^rd Street/Lexington Avenue station was awarded to Jaudlau Contracting on January 13^th 2011 and is mobilizing to the site. MTA expects to award the 86^th Street station contract later this month or early next month to Skanska/Traylor JV, barring any issues, and for construction to start this summer.

The Skanska/Traylor JV has plenty of experience navigating the tough New York construction contracting conditions. Skanska in joint venture with Schiavone and Shea is working the $337 million Second Avenue subway Phase 1 tunneling contract as well as the $447.2 million contract on New York's $2.1 billion No 7 Line Subway extension to 34^th Street. Traylor Brothers, in joint venture with Granite and Frontier-Kemper, is set to begin excavation of the Queens soft ground tunnels on New York's East Side Access Project. When complete in December 2016, Phase I of the Second Avenue Subway will serve 213,000 daily riders and will reduce travel times by up to 10 minutes or more for those traveling from the East Side to West Midtown.

References

Blue Plains project team selected in DC - TunnelTalk, Mar 2011
New York breakthrough in Times Square - TunnelTalk, June 2010
Slurry TBMs ready to tackle New York ground - TunnelTalk, March 2011

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