The Nov. 23 resumption of train service from New Jersey into New York City’s former World Trade Center site after a $566-million overhaul of stations and track damaged on Sept. 11, 2001, marks a crucial milestone in lower Manhattan’s renaissance. The project’s centerpiece is a $323-million "temporary" station for thePort Authority Trans-Hudson (PATH) line in New York City that will serve as a no-frills stand-in for the $2-billion downtown transportation megacenter to come by the end of the decade.

The station opened a month early and debuted five months after the reopening of the Exchange Place station across the Hudson River in Jersey City, N.J. That station underwent $137 million of work, including the 110-ft extension of platforms to accommodate 10-car trains. That modification was considered more than 20 years ago but ruled out because of the cost and required service lapse, say officials of the Port Authority of New York and New Jersey, which runs PATH. The reconstruction was funded by the Federal Emergency Management Agency, Port Authority and insurance.

The Port Authority spent $106 million restoring 1-mile-long tunnels below the river that suffered major flood damage after the 9/11 terror attacks. "Tunnels were flooded up to roof height," says Lou Menno, a manager of the Port Authority’s priority capital program. Water from seepage and firefighting also destroyed many of the 150 cables and 4,400 wires inside.

The PATH system consists of five tunnel extensions of varying elevations shaped like a hand. It needed major work to repair tunnel linings and to accommodate trains that were rerouted from Exchange Place to another Manhattan PATH station. Track, electrical equipment and ducts were replaced and the Port Authority spent more than $16 million on new track signals and $2 million on a new computer-run switching center that replaces the old relay system.

It took weeks after 9/11 to pump out the water, says Tom Groark, Port Au-thority assistant chief engineer. Officials say the reconstruction required contractors to work "double and triple shifts." Construction was managed by a joint venture of Tully Construction Co., Flushing, N.Y.; A.J. Pegno Construction Corp., College Point, N.Y.; and Yonkers Contracting, Yonkers, N.Y. The team is set to receive a $5-million early completion bonus, sources say.

The 16.6-ft-dia, iron-lined tunnels now have a new track system of direct- fixed neoprene fasteners instead of the old ties and ballast. Duct banks now feature fiberglass reinforcement. The cast-iron lining of compressed air tunnels built in 1905 "is as good as the day it was put up," Groark says.

Reconfiguring tunnel extensions to allow trains to turn around and switch tracks required nearly 11,000 cu yd of excavation. Drill-and-blast operations were challenging because of the risk of damage to buildings above, says Groark.

Engineers decided to use Austrian roadheader machines to excavate the soft mica encountered, says Raymond Sandiford, the Port Authority’s chief technical engineer. But the machines were high-maintenance and sometimes went down "for days and weeks," he says.

Next spring, architect Santiago Calatrava will present designs for the permanent transportation hub that will link PATH with subway lines, says a Port Authority spokesman. Five bidders have been short-listed for the construction management contract. The entire hub is set for a 2009 opening.