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Ingenuity, Non-Traditional Methods and Technology Speed Restoration of PATH Service to WTC Site

July  2003

Work to restore PATH service to Downtown Manhattan is ahead of schedule with resumption of train service to a new temporary passenger terminal at the World Trade Center site expected in November.

The PATH Terminal at the World Trade Center served some 67,000 passengers per day when it was destroyed in the September 11, 2001 terrorist attacks. With resumption of PATH service to Downtown Manhattan as its top priority, the Port Authority forged a unique partnership that allowed contractors to order materials and mobilize for construction even as engineers were completing design work. This collaborative approach, coupled with non-traditional sequencing of tunnel work and track installation, promises train service to the World Trade Center site will begin fully a month ahead of the original end of December 2003 goal.

Demaged PATH WTC Terminal after 9/11 The collapse of the World Trade Center caused severe flooding of the PATH tunnels under the Hudson River between the World Trade Center and Jersey City damaging track systems, cables, duct banks and concrete, electrical components including switch and signal equipment, and track ballast.

The work to restore the two-mile long tunnels began in March 2002. Only the 16 foot wide cast iron tunnel ring liners were left once all water damaged equipment had been demolished and debris removed-the very rings that became famous a century ago as the "Hudson Tubes." Remarkably, these cast iron rings were sound, having sustained little damage. However, corroded and leaking ringbolts had to be repaired. The ring liners were power-washed, and concrete invert, track bed Duct Bank Demolition and track support structure restored. Finally, duct banks, cables for high voltage, traction power, signals and communications installed, not to mention the lighting, drainage, fire protection, in-tunnel communication and signal systems had to be replaced. Over 11,000 feet of new track, 5600 feet in each tunnel, along with third rail, had to be installed.

Every opportunity was seized to accelerate progress even while upgrading materials and construction techniques to state of the art industry standards. Traditional construction methods would call for the installation of conduits and duct banks after the installation of track. This order was reversed so that concrete delivery trucks could use the tunnel floor and feed material to the worksite. First fiber reinforced epoxy conduit replaced the old clay ducts and steel reinforced concrete duct banks succeeded the old asbestos lined duct banks.

"This was a special challenge in tunnels where clearances were very tight--as small as two inches beyond the dynamic envelope of a PATH train," says Jim Palmer, a Program Management Consultant. "We had the real fear that as we rebuilt the tunnels, trains might hit the walls," he adds. The solution was building a "brush car" template to accurately measure clearances.

Continuous Welded Track Another technological advance is the use of continuous-welded-rail in place of the standard 39-foot lengths of rail that give that familiar clickety-clack sound to most railroads. Some 560 tons of 115lb/yard rail in 39 foot lengths and 150 tons of 100lb/yard rail were delivered to the World Trade Center Bathtub, and welded using an electric fusion process into 1440 foot continuous lengths.

"Using a big powerwheel, the welded rails were pushed and dragged like shining strands of linguini into the tunnels," says Tom Groark, Manager, Construction Management Division.

Once in place, the rail sections were bolted together and field welded forming continuous-welded-rails. According to Ernie Perry, Assistant Resident Engineer-Track, the 37,644 linear feet of rail sections required over a thousand individual welds in the field using a process similar to casting molten metal.

Direct Fixation Connections Continuous-welded-rail does a lot more than get rid of the old clickety-clack. It is stronger and more dependable and gives a smoother ride. In addition, with the introduction of the direct fixation fastener system to anchor the rails instead of using customary wooden railroad ties and gravel ballast for securing rail to the track bed, trains will sway less in the century-old tunnels.* Passengers are sure to notice a smoother, quieter and more comfortable ride.

Passage to Escalator Bank After the attacks, all that remained of the original PATH World Trade Center Terminal was part of a platform and an escalator bank. In order to restore train service to the site as quickly as possible, a temporary terminal is being built at the same location as the destroyed facility. This enables engineers to utilize previous alignments and minimize additional excavation and foundation work. However, a new traction power substation located adjacent to the former South Tower footprint has been designed to support future construction of floor levels up to the street level. This "over build" scenario is intended to eliminate the need to build future support columns through the substation in the future development of the World Trade Center site.

The track and platform configuration of the temporary station will mimic the former station. The terminal will have a mezzanine above the platforms where turnstiles will be located, with stairs and elevators connecting the two levels. From the mezzanine, passengers will follow previous pedestrian pathways to escalators, elevators and stairs up to street level on Church Street.

Temporary Station Platform Level The temporary station was designed to facilitate the quickest restoration of service possible and some customer amenities will not be available until a permanent terminal is constructed. All public access areas and track zones will be open, though weather protected. There will be no public toilets, shops or eateries, but the terminal will be fully ADA compliant and fully accessible.

Temporary Station Mezzanine Level The completion of the temporary station and resumption of PATH train service to the World Trade Center site is the foundation of restoring commuter and visitor access to Downtown Manhattan even as planning proceeds for a Lower Manhattan Transit Complex. Envisioned as a combination of a new PATH Terminal, the MTA's new Fulton Street Transit Center, and pedestrian Temporary Station Entrance connections linking these with the World Financial Center and the WFC Ferry Terminal, the Lower Manhattan Transit Complex is slated for completion, in phases, over the next three to six years.

*

 For more information please see January 2003 website article "Direct Fixation Fasteners Bringing : the PATH Tunnels Into the 21st Century"

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