A subway line grows in Manhattan

Delivering the first major New York City subway expansion in 50 years

On the drawing board since Second Avenue’s elevated trains were dismantled more than 60 years ago, the Second Avenue Subway line in Manhattan’s Upper East Side consists of three new stations at 96th, 86th and 72nd streets plus an upgraded station at 63rd Street. The first major New York City subway expansion in 50 years, this landmark $4.45 billion, 1.8-mile-long first phase line provides new subway access to communities on the far East Side and reduces overcrowding on the Lexington Avenue line.

Balancing development and community

Constructed in the densely populated Upper East Side, the first phase of Second Avenue’s subway expansion required a thoughtful, comprehensive approach to recognize social, economic and sustainability issues.

Second Avenue Subway was built amidst an intricate neighborhood backdrop of buildings, infrastructure and transit. Community input was key in the project’s development, notably with station placement along the line. This expanded line is providing numerous community benefits in the years since its opening. It has sparked transit-oriented development along Second Avenue, reduced pollution by cutting the volume of taxis, ride shares such as Uber and Lyft in the neighborhood while offering new ADA-accessible stations to increase mobility.

Setting the standard

Our design team developed new subway station design standards that extend beyond conventional engineering — standards that can be adopted across the entire subway system. The bored tunnel was the city’s first to not use rebar in the final liner. Bypassing reinforcing steel in the concrete liner, steel fibers were used for flexural strength and to control cracking, with polypropylene fibers used to control explosive spalling in the event of a tunnel fire. In lieu of steel, aluminum composite was used for the third rail to improve train conductivity and reduce energy loss. Quieter station environments were created by lining ceilings with perforated metal panels backed with sound-absorbing fiberglass and using joint-free running rails with concrete ties encased in rubber.

Delivering a project of this scope on time and within budget was a major achievement for the AECOM-Arup joint venture project team. The line was constructed below some of the world’s most congested infrastructure, which required managing a maze of utilities and building foundations. The three subway stations rank among North America’s largest underground excavations, at nearly 64-feet wide, 100-feet deep and 1,600-feet long.

Complex challenges meet innovative solutions

Tunneling, structural and geotechnical: Tying a new subway line into an existing, 100-year-old system is a Herculean endeavor, especially since this line sits below some of the world’s most congested infrastructure and ground conditions vary from the hard rock of Manhattan schist to the soft soils of old river beds and swamps. One particular challenge involved an area of fractured, weathered rock at the start of the east tunnel. Ground freezing was determined as the best approach to allow a hard-rock tunnel boring machine (TBM) to safely pass through, a decision that necessitated adjustments in tunnel sequencing but still kept the project on track. Ultimately, a TBM weighing 485 tons and measuring 450 feet long was used to excavate 12,800 feet of twin-track tunnels measuring just over 22 feet in diameter.

Social: SAS stations are safe and welcoming, with high ceilings, column-free public spaces, Wi-Fi access and added security measures. Each station now has street entrances with escalators and ADA-accessible elevators — features much appreciated by riders who long endured stairway-only access. Energy-efficient lighting and graphical signage aid passenger orientation and reinforce station identity, which is further established through one-of-a-kind art installations anchoring each station. These monumental works of art, commissioned specifically for this project, collectively make SAS the largest permanent public art display in the state.

Better transit, better living

Second Avenue Subway is making an important mark on the Upper East Side. Within the first five months of the line’s opening, more than 176,000 riders a day were taking advantage of the increased mobility offered by Second Avenue Subway, proving that this project is more than better transit — it’s better living.

Major awards and accolades

  • AIA NYS Excelsior Merit Award for New Construction, 2021
  • ACEC Engineering Excellence Awards National Grand Award, 2018
  • ACEC NY Chapter Empire Award, 2018
  • ACEC NY Chapter Diamond Award, Transportation, 2018
  • ACEC NJ Chapter Honor Award, Large Project, 2018
  • ASCE Outstanding Civil Engineering Achievement Award, 2018
  • ASCE Met Section Construction Achievement Project of the Year, 2017
  • Engineering News-Record Best of the Best Airport/Transit Project, 2017
  • Engineering News-Record NY Region Project of the Year, 2017
  • Engineering News-Record NY Region Best Airport/Transit Project, 2017
  • British Construction Industry Awards International Project of the Year Finalist, 2017
  • International Tunneling Association Major Project of the Year, Highly Recommended, 2016
  • NY/NJ Concrete Industry Board Corbetta Awards Annual Award Winner, 2013
  • US Environmental Protection Agency Green Building Design Award, 2004