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RECONFIGURING RAILWAYS

Infrastructure Improvements Ready
Jamaica Station for the Future

Jamaica Station comes alive each weekday with more than 200,000 passengers. Located in Queens, New York, it is the main rail station providing access to Manhattan for more than 2.3 million local residents.

The largest transit hub on Long Island and one of the busiest stations in the country, the Long Island Rail Road’s (LIRR) Jamaica Station serves as a key transfer point for LIRR riders and as critical infrastructure for LIRR operations. The station also provides a major connection to the Port Authority of NY & NJ’s AirTrain service, which ushers travelers to and from John F. Kennedy International Airport.

To handle the increased station traffic resulting from the East Side Access project—LIRR’s new connection to Grand Central Terminal—Jamaica Station was in need of an upgrade. Plans to improve station efficiency, increase train throughput, and prepare for East Side Access are part of the LIRR’s $301 million Jamaica Capacity Improvements (JCI), Phase I Project.

As part of JCI Phase I, the Johnson Avenue Yard Reconfiguration design-build project established the groundwork for a key future enhancement to the station complex—a new station passenger platform dedicated to Atlantic Terminal service. Providing resident engineering services for the construction management of this project, Gannett Fleming supplied key expertise needed to assist LIRR and guide this project through complex construction challenges and ultimately to a successful on-time completion.

Crossing Complexities

As a bustling transportation hub, all but one of LIRR’s 11 branches travel through the Jamaica Station complex, which includes five island platforms, 11 through tracks, and various train storage yards. A major source of station operation inefficiencies is the cross-routing of Atlantic Terminal and Penn Station train traffic, as well as station dwell-time caused by Atlantic Terminal and Penn Station connecting train service at Jamaica. These actions affect train throughput within the station—a key concern as it relates to increasing service through Jamaica for the future East Side Access.

Laying the Groundwork

Positioned on the south side of Jamaica Station, the Johnson Avenue Yard needed to be reconfigured and upgraded to make room for the new platform. This new structure, Platform F, as well as associated track reconfigurations, will isolate the tracks leading to and from Atlantic Terminal and mitigate associated route conflicts with Manhattan-bound trains, thereby allowing increased train throughput in the station and providing for the future needs of Grand Central Station service plans.

Key elements of the Johnson Avenue Yard reconfiguration project included realigning and reprofiling 5,500 feet of track and 350 feet of the yard lead track; installing four new track switches; raising the elevation of the eastern half of the yard; developing an underground track support system for a portion of the yard lead track under the AirTrain building; constructing a 1,230-linear-foot (LF) retaining wall system; and implementing new lighting, PA, and closed-circuit television systems. Because of the location of the future platform, an existing utility duct bank and manhole system containing critical railroad power, signal, and communication cables also needed to be relocated.

Digging for Solutions

From the beginning, the Johnson Avenue Yard Reconfiguration project presented significant challenges, particularly when it came to constructing a system to support the lead track’s raise and realignment. This micropile-reinforced structure had two objectives: support the lead track and eliminate any new loading on the AirTrain building foundation caused by the addition of Platform F and its associated tracks.

The team began with limited information about the existing AirTrain building tieback foundation around which the micropiles needed to be installed. To learn more, the team excavated 60 test pits up to 8 feet deep at 60 locations. This surveying exercise located more than 130 tiebacks, and projections were made based on the observed headings of the exposed tiebacks, as well as known obstructions around which these tiebacks were installed. This provided the design-build team with enough knowledge to move forward with drilling the micropiles, while avoiding the structurally critical tiebacks.

Despite the low headroom clearance of 16 feet, the team drilled 77 micropiles through the existing lead track and tieback area and then tested to make certain the infrastructure could handle the relieving platform. This was accomplished during the limited time the train yard could be shut down for the project—only seven 48-hour weekends and one, 28-day period of 24/7 work within a two-year timeframe.

High-Voltage Challenge

Another issue the team faced was relocating critical railroad utilities, including 26,000 LF of power supply conduits and a 21,000-LF communication conduit system. These conduit systems contained high-voltage signal power feeds; third rail power feeds; signal and substation fiber optic communication lines; and commercial fiber optic lines. These utilities needed to be relocated to make way for the new platform and its associated tracks.

The original design proposed rerouting the conduits via two duct banks running in separate trenches at the north and south borders of the yard, built in two separate stages of construction.

After reviewing the original plan, the project team developed an alternative—running all the duct banks in a single trench, reutilizing a portion of the existing duct bank system, and constructing it all in a single stage of work. This modification reduced the number of times these duct banks crossed each other and crossed under the tracks. The revised plan also avoided the potential for increased excavation work that would be required to dig deeper trenches and support the weight of the train. The design modification also improved access to the conduits, preventing the need for track outages during future maintenance.

A Platform for the Future

As a result of these infrastructure improvements, the Johnson Avenue Yard project made the long-envisioned Platform F possible. With construction of the platform scheduled to be underway in late 2016 and completed in 2019, the busy transit hub will keep trains and passengers on the move, while preparing for the future system expansion to Grand Central Terminal.

Contact Kenneth Cho, PE, via email for more information.

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