How the Second Avenue Subway Phase 1 program turned 100 years of engineering heritage into a sustainable legacy for the future
For nearly six decades, New Yorkers have imagined an Upper East Side with subway access, not least because the daily reality for many Upper East Siders has been overcrowding, delays and bottlenecks on the only available nearby line, Lexington Avenue.
This increased burden on the neighboring line was having a knock-on effect on an already stretched network of 24 lines that moves over 8.5 million passengers through a subway system built well over 100 years ago. In short, a new line for the Upper East Side was badly needed.
New York’s Metropolitan Transportation Authority (MTA) commissioned the AECOM-Arup Joint Venture (AAJV) as the prime engineering and design consultant for the Second Avenue Subway Phase 1 program — the first major expansion of the New York City Transit (NYCT) subway system in over 50 years.
Combining three new stations, 1.8 miles of tunnel and track, and ten separate construction contracts, this US$4.45 billion program demanded multidisciplinary capabilities, close coordination of design engineers and construction professionals, and global engineering expertise, over a 15-year period.
As AECOM’s Rich Paupst describes, this comprehensive engagement between AECOM and our partners and contractors is critical to the success of complex programs. “It helps to streamline the build process,” he comments, “minimizing the need to revise designs midway through. Today, design and build procurements are much more effective because they are integrated and collaborative.”
There were certainly many challenges to surmount in tying the new development into an existing system that dates back to 1904.
The site sits beneath and amidst some of the most congested urban infrastructure in the world – a maze of telecommunications, electrical, gas, steam, water, and sewage lines. We were able to draw on AECOM-Arup's shared geotechnical expertise in foundation and landfill engineering, hydrology, engineering geology and other specialized services to not only devise far-sighted solutions, but to reduce design and construction risks in the process.
Similarly, because we had optimized the design to reuse the existing station and its tunnels on 63rd Street, the ventilation system required significant updates to comply with modern codes and standards, but with limited space for the mechanical and electrical systems necessary. Through careful planning, creative engineering, and close collaboration with our partners, we brought the existing systems up to code whilst remaining cost effective.
From these engineering challenges emerged many opportunities for us to deliver on our core values of improving social outcomes and delivering sustainable legacies that drive positive change.
In the tunneling program, for example, we accommodated escalator and elevator connections to street level – a huge improvement on the typical New York stairway-only access.
To create a less stressful environment, we drew on innovative acoustics to reduce train noise, and modeled passenger foot flow to “design out” unpleasant and unsafe overcrowding.
As for the stations themselves, which rank among North America’s largest underground excavations, our priority was that they should not only deliver fully and cost-effectively on operational expectations, but that they should also be, as Paupst puts it, “an architecturally beautiful space that all passengers would find visually stimulating and take pleasure in using.” To this end, the stations adhere to sustainable design guidelines and rules for architectural detailing and are compliant with the ADA (Americans with Disabilities Act).
The entire program has been, as Paupst comments, “a transformative project that takes a leap forward in engineering and design innovation of a transit system.”
But in addition to engineering achievement and hard metrics, the results and outcomes also tell a story of human and environmental benefit. The program has delivered the mobility and accessibility New Yorkers have been waiting for – and its design helps ensure these qualities will endure, sustainably, for generations to come.
The entire program has been, as AECOM’s P.E. (Planning & Economics) Project Manager Liam Dalton comments, “a transformative project that takes a leap forward in engineering and design innovation of a transit system.”