By: Stephen Burke, Marketing Communications Manager – Sika Sarnafil, Canton, MA

Sika Corporation continues to be an innovative leader in the construction of tunnel systems around the globe, having contributed mortars, concrete and a variety of waterproofing products and systems for projects located in more than 70 countries.

Not surprisingly, the company has an active role in the complex and challenging expansion of the New York City subway system now taking place nine stories beneath that city’s streets — a project calling for construction of new underground stations and nine miles of new tunnels. Thus far, more than 3,000,000 square feet of specially formulated Sikaplan WP 1100 waterproofing membrane has been delivered to seal off groundwater from underground structures now being fashioned out of everything from hard rock to sand.

In addition to the SikaPlan WP 1100 membrane, the waterproofing system relies on Sika Greenstreak PVC waterstops to create watertight compartments that further prevent groundwater ingress into the finished stations. To date, Sika Greenstreak has provided more than 100,000 linear feet of waterstop for New York City subway projects.

Prior to just five years ago, the concrete admixtures group did not focus on this market segment; but just in the last few years, Sika has also provided thousands of gallons of concrete admixtures for the concrete to build the new stations and line the tunnels. Our admixtures help improve the plastic properties of the concrete as well as the long term durability, and our shotcrete accelerators have helped to stabilize subgrade after blasting or drilling.

The New York City transit system hosts more than 7.4 million riders per day, making it the busiest transportation system in the United States and the fourth busiest in the world. The city’s subway, established in 1904, is the heart of the system with 5.1 million riders per day, about 475 stations (the most in the world), and more than 800 miles of track

The design and construction of tunnel structures is a laborious process. New York City’s Second Avenue Subway Line, seen in the accompanying photos, was first Close-up of Sika Greenstreak waterstop at a joint intersection. All photos – NYC Metropolitan Transportation Authority / Patrick Cashin conceived more than 50 years ago and is only now approaching reality. Sika Sarnafil first began discussing waterproofing system solutions for this project with engineers from the New York City Metropolitan Transit Authority back in 2000. After years of planning and consultation, WISKO America, Sika Sarnafil’s Elite tunnel contractor, started construction in 2010.

Sika Sarnafil has had a twenty-year relationship with WISKO and the Chantilly, Virginia-based company has installed more than five million square feet of Sarnafil membrane to waterproof underground structures throughout the United States. Sika Greenstreak has also had a long history of partnering with WISKO, providing hundreds of thousands of linear feet of their proprietary waterstop profile along with thousands of factory made fabrications. Other Sika Greenstreak waterproofing products provided to WISKO include Sikafuko injectable hoses, injectable resins, Sika Dilatec, and the Sika Hydrotite waterstop.