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Superstorm Sandy: Fix&Fortify Efforts Continue

 
Heeding the Forecast


On Friday, October 19, 2012 Sandy formed as a tropical depression.  By that time, we were already monitoring the weather services and had begun planning for the worst.  By the following Wednesday, concrete measures were being taken by maintenance crews who were out covering subway sidewalk grates and erecting barriers to protect the more than two dozen entrances to Lower Manhattan subway stations.

Plans had previously been developed for an orderly shutdown of the MTA’s massive transportation system.  A similar shutdown had been put in place a year earlier for Hurricane Irene.  It was rightly thought that halting all services in the hours prior to the storm would make it far easier to restore subway, bus, and commuter rail operations once the danger was passed.

More immediate preparations began on October 28, hours prior to the storm’s arrival, with the preemptive suspensions of the MTA’s subway, bus, and commuter rail services.  Trains and buses, however, were not halted until the conclusion of a daylong evacuation effort, moving tens of thousands of New Yorkers from the City’s low-lying areas.  When that task was completed, all trains and buses were moved to safe areas in the system.

The timing could not have been worse
There is no good time for a storm of this ferocity, but it could hardly have been worse as Sandy’s arrival was timed to a high tide.  Transit officials were stunned to learn that the storm surge breaking over the seawall at the Battery was more than 14 feet.  The force of the waves battered down the barricades erected to protect the South Ferry terminal of the No. 1 Line.  The station is situated at the southern tip of Manhattan just steps away from the Staten Island Ferry Terminal.  Waters from New York Bay stormed through the broken barriers and filled the station to a depth of 80 feet, 35 feet deeper than New York Harbor’s main shipping channel.  In Southeast Queens, the high water had virtually washed away the A Line on Broad Channel – the link between Howard Beach and the Rockaways.  Also gone was NYC Transit’s subway train test track used to evaluate new technology subway car performance.

In the storm’s wake, nine of NYC Transit’s 14 under river tubes were flooded and heavily damaged, most notably the Montague Tube.  The loss of electricity to the lower Manhattan area rendered the pumping system inoperable, leaving the tube flooded for ten days.  Once power was restored, more than 27 million gallons of water had to be pumped out before work could begin to make it safe for the passage of trains.

Repair of the A Line right-of-way leading to the Rockaways was completed first, including the installation of a three-mile flood barrier designed to protect the right-of-way during future storms.  The Montague and Greenpoint under-river tubes have been largely addressed, repairs to the Steinway tube are underway, and plans are ongoing to begin work on other critical facilities hard hit by Sandy. Steady progress is being made but many years of work still lie ahead.  

“Sandy was a magnitude greater than anything New York’s mass transit system has ever faced,” noted MTA Chairman & Chief Executive Officer Thomas F. Prendergast.  “The amount of work performed for service restoration was truly phenomenal.  Now, however, we are involved in a years-long process to make permanent repairs to our infrastructure while simultaneously fortifying it against future storms.”        

“Work at the South Ferry terminal and at subway yards around the City are underway, and NYC Transit has been storm-proofing dozens of locations in the low-lying areas at the southern end of Manhattan.  The Rutgers, Cranberry, Joralemon, Clark Street, Canarsie, and 53rd Street Tubes are also in need of major repairs and work to make the tubes more resilient. Scheduling these projects along with all the other capital work in the system is complex, given the goal of minimizing the impact to our customers and also to regional economy,” he added.

Water, water everywhere
How does water enter the subway system?  To a large extent, the same way you do; down the stairs.  Transit is currently at work developing flood mitigation measures for 27 entrances at seven Lower Manhattan subway stations: 

  • Old South Ferry
  • New South Ferry
  • Whitehall St
  • Bowling Green
  • Rector St   R subway
  • Rector St  1 subway
  • Broad St

The entrances will be protected by deployable stair covers, flood doors, and marine doors.  Other means of ingress include sidewalk grates (vents) and manholes.  Therefore, 72 manholes will be protected by watertight inserts, the sealing of conduit-duct penetrations, and the replacement of the manhole casting.  Water also comes into the system through sidewalk ventilation vents.  Throughout Lower Manhattan, 376 vents will receive deployable vent covers and mechanized closure devices.  Transit’s efforts are designed to protect the system from a Category 2 storm and the resulting surge.

Currently, there are several projects in design or construction aimed at preventing subway flooding through stair entrances, sidewalk ventilator gratings, personnel and equipment hatches, emergency exit hatches, manholes, elevators and fan plant structures.  Solutions mostly rely on applying methods commonly used in similarly vulnerable systems.  However, NYC Transit has been innovating to adapt solutions unique to the challenges of our system.  The mechanized closure devices referenced above are one such example.  Retractable fabric closures – to protect vulnerable station entrances – will be the newest innovation.

The problem of high water does not just exist in Lower Manhattan.  New York City is surrounded by water and has 538 miles of coastline.  Several of NYC Transit’s subway car storage and maintenance facilities are situated near water and suffered severe flooding during Sandy’s assault. 

No fun at Coney Island that day
During the storm, surging floodwaters swamped yard locations at 207th Street, 148th Street, Rockaway Park, and Coney Island, heavily damaging critical switching and signaling equipment.  Subway cars had been relocated to tracks and storage areas at higher elevations hours before the storm’s arrival, but the critical infrastructure that delivers power and provides signaling and track switching in the yards was left severely damaged.    

Coney Island Yard, which has storage tracks for 1,800 subway cars, is the largest rapid transit storage and maintenance facility in the world.  The Yard occupies approximately 75 acres of land. Situated near Coney Island Creek and the Atlantic Ocean, the facility was swamped under several feet of water.  

A huge and complicated operation generating hundreds of train movements each day, Coney Island Yard was reduced to a train-handling operation from the early 20th century.  With the tower knocked out of operations, switches, directing stored trains to and from the proper tracks, had to be thrown by hand. 

To guard against future flooding of Coney Island Yard, construction of temporary mitigation is currently ongoing and is expected to be completed by end of December 2014.  Long term mitigation, however, including the addition of a perimeter wall is in design with design completion scheduled for latter part of 2015.

These measures are projected to be enough to protect against a 100-year flood as well as a significant storm surge.  Protection will also be provided for components located in the area beneath the elevated Stillwell Terminal complex.  Long term solutions include perimeter flood walls, automatic flood gates, and other stormwater control measures.

Located in the Inwood section of Manhattan, the 207th Street Yard will be protected on interim basis by Trap Bags and metal flood barrier fencing, interlocked sheeting, and deployable yard entrance gates.  The yard sits on the Harlem River and fell victim to massive flooding during Sandy.  Fortification measures here, aside from protecting the yard, will also help prevent flooding of the Dyckman Street and 207th Street stations on the A line both of which flooded during Sandy.

Trap bags and deployable yard entrance gates will also be called into service in the Rockaways.  The components will be installed at Hammels Wye to protect critical electrical facilities against a 100-year storm.

The problem we currently face, however, is that there is the likelihood that 100-year storms could come along a lot more frequently than in the past.  NYC Transit customers can be assured that we go into future hurricane seasons far stronger and more prepared than we have ever been.

 

 
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