Mott MacDonald celebrates completion of landmark East Side Access megaproject

For more than 20 years, Mott MacDonald has played a key part in the creation of East Side Access, the most transformative project for New York City public transit in more than a century.

As tunnel consultant to the Program Management team for East Side Access, Mott MacDonald provided essential tunneling expertise that enabled the MTA to meet the daunting technical challenges of the project, including tunneling methods, ventilation systems, fire and life safety, and installation of the tunnel lining.

Andy Thompson of Mott MacDonald served as Program Executive for more than six years, overseeing construction for the entire project. Mott MacDonald provided construction management for more than $1 billion of work, including the first use of slurry tunnel boring machines in New York City.

Mott MacDonald also managed the tunnel crossing of Northern Boulevard in Queens — at $1 million per foot, the most expensive stretch of tunnel ever built in the US. The Northern Boulevard crossing passed through glacial deposits about 55 feet below the groundwater table. The tunnel passed beneath a railway line, a six-lane street, and a subway structure. An arch of frozen earth was required to protect the tunnel from contaminated groundwater plumes.

About 7 miles (11 kilometers) of new tunnel were driven beneath Queens and Manhattan. The diameter of each tunnel is about 22 feet (6.7 meters), with some tunnels circular and others arched. About 17,500 feet or more than three miles (5.3 kilometers) of previously constructed tunnels were also rehabilitated as part of this enormous project.

New rail lines run from the Harold Interlocking yard in Queens, already the busiest railroad interchange in the country. Tunnel portals under the Sunnyside Rail Yard connect to the 63rd Street tunnel, which was extended for about one mile through glacial tills and fill.

According to the MTA, East Side Access will provide a direct connection for all 11 LIRR lines to Grand Central Terminal and Midtown East for all 11 Long Island Rail Road Lines. Over 160,000 passengers per day will save as much as 20 minutes in each direction. Crowding at Penn Station will be alleviated, and the new Grand Central Madison terminal will offer shops, restaurants, waiting areas, and free WiFi.