Balancing Act

Delicate Moves Fit New Transit Hub into Crowded World Trade Center Footprint

by Natalie Keith

Coordinating construction of a $2.2 billion transit center in a crowded urban environment would present hardship under most circumstances, but the task of building the World Trade Center Transportation Hub, set to open in 2009, defies even conventional standards.

The project faces exacting space constraints; complicated logistics that include keeping subway service in operation; intense public scrutiny of its design and progress; and one of the world's busiest construction sites, with work on the 2.6-million-sq-ft Freedom Tower, a chiller plant, and the Sept. 11 memorial - as well as three new office towers on the way.

"We have to work closely with all of the stakeholders on a day-to-day basis to reach a consensus on a range of construction issues," says Steve Plate, director of the Priority Capital Programs Department for the Port Authority of New York and New Jersey, which owns the World Trade Center site and will operate the hub.

The new facility, designed by Santiago Calatrava, a Spanish architect, will offer passengers from the Port Authority's PATH transit system an easy transfer point via underground passageways to the subway system operated by New York City Transit. The PATH, which ferries passengers 24 hours a day between various stations in New Jersey and Manhattan, currently uses a temporary station that opened at the World Trade Center in 2003 after the original station was destroyed in the terrorist attacks.

The Calatrava design calls for a soaring arc of steel beams and glass, which will frame a main hall currently programmed to be 340 ft long, 112 ft wide, and 111 ft tall, with multiple levels and a retractable roof. The building will be flooded with sunlight by day, and glass paving in the plaza and mezzanine levels will allow some sunlight to filter 70 ft down to the five tracks below.

The distinctive design will not only be passenger-friendly but also create a sense of place in Lower Manhattan, says Rick Bell, president of the New York chapter of the American Institute of Architects.

"It's not just a gift from a transportation standpoint - it's creating a great public space," he says. "It will be interesting to see what happens in that space other than commuters passing through it."

The hub will house the permanent PATH terminal with a track and platform level, a mezzanine level, and access to streets surrounding the World Trade Center site. It will offer underground pedestrian connections to stations for 13 New York City Transit subway lines and link to the World Financial Center Ferry Terminal via a West Street underpass.

The project's significance to the region is hard to overstate, says Robert Yaro, president of the Regional Plan Association, a local transportation planning group. The federal government has given it priority, funding about $1.92 billion of the project, with the Port Authority providing the remaining $300 million.

When completed, the hub will finally rework a facility that was confusing, even for seasoned travelers, Yaro says.

"It was never designed as a system," Yaro adds. "There are very difficult connections. Visitors find it almost impossible to navigate."

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Construction Effort Moves Ahead

Construction began in September 2005 on the facility with Phoenix Constructors JV, a consortium of four major construction managers: Fluor Enterprises of Irving, Texas; Slattery Skanska, a division of Skanska USA Civil of New York; Granite Northeast Construction, a division of Granite Construction of Watsonville, Calif.; and Bovis Lend Lease of New York. The joint venture is handling the project on a guaranteed maximum price contract.

Keeping to the schedule is a big task, Plate says. The team closely evaluates the timing and scope of procurement packages, reviews designs, and conducts value engineering and constructability reviews as part of the effort to stay on track.

The budget also presents a major hurdle. A recent memo from the construction team warned that the current design could increase the project's costs to $3.4 billion.

"The Port Authority is working closely with Santiago Calatrava, the design team, and the contractor to explore all available options, including constructability, staging, and the sequencing of construction - all of which have the potential to significantly affect cost - while retaining Calatrava's signature architectural design," Plate says. "We are committed to delivering the project on time and on budget."

Tasks completed so far include pre-condition surveys, installation of test piles, and relocation of PATH utilities and the third rail within one of the New York City Transit subway line structures. Other work the project team has finished includes installation of monitoring instruments and minipile casings along the track's centerline; relocation of perimeter security fences and a 24-in water main along Vesey Street; and demolition and removal of portions of an old tunnel structure, which served the PATH's predecessor, the Hudson & Manhattan trains.

A major task on the team's agenda now is extensive underpinning for the station box and tube for New York City Transit's 1 subway line. The team has installed minipiles and structural steel framing within and around the subway structure to provide support during excavation around it. To date, approximately 150 lin ft of piles have been installed.

"[We're installing] 1,000 lin ft of underpinning in total," Plate says.

The project team also must coordinate with other work onsite, including planning for the future office buildings that Silverstein Properties is developing. The east bathtub, which is being constructed on the south side of the hub's site, is being prepared so that construction of two of the office towers can begin in early 2008.

The construction effort for the bathtub will include fabrication and installation of 60 slurry wall panels stretching 1,200 lin ft, Plate says.

By year's end, the project team anticipates it also will have erected 350 lin ft of a north-to-south shear wall to an elevation of 225 ft, placed 4,900 cu yd of concrete, and used 50 tons of reinforcing steel. Other upcoming work includes creation of a new temporary entrance on Vesey Street to allow for construction of the permanent station in the space now occupied by its Church Street entrance. Steel erection above grade should begin next year.

While no decisions have been made on changes to the design to get the project back to its original budget, Bell says one aspect the Port Authority could revisit is distribution of commercial uses.

"I'd like to see more commercial activities on the ground floor," he adds. "Most of it is on the mezzanine level."

Bell also says one of the most remarkable features - bringing natural light to the hub's lower levels - poses a puzzle.

"Bringing light down from the street isn't done often," he adds. "Balancing the benefits of bringing natural light with creating a useable public plaza is a design problem."

Key Players

Owner: Port Authority of New York and New Jersey

Contractor: Phoenix Constructors - Fluor Enterprises; Skanska USA Civil; Granite Construction; Bovis Lend Lease

Architect: Downtown Design Partnership - STV Inc.; DMJM Harris; Santiago Calatrava

Program Manager: PB Americas, URS