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PRESS RELEASE
FOAM-TECH SUPERINSULATES “THE BIG DIG”
August 14, 2001
North Thetford, VT
FOAM-TECH is pleased to announce that it has been contracted by Modern Continental Construction Co., Inc. to install polyurethane foam insulation for the Fort Point Channel Crossing Project portion of “The Big Dig” in Boston, MA
The Project
The Big Dig (officially known as The Central Artery/Tunnel project) is the largest, most complex, expensive and technologically challenging highway project ever undertaken in the U.S. It represents a unique challenge in that it is being built in the heart of the city, almost completely underground or underwater. It is a state-of-the-art highway system that is being built under the existing infrastructure system without disrupting the current traffic capacity or access throughout the construction.
The History
Boston, Massachusetts has a major traffic problem consisting of an outdated Central Artery made up of six lanes running through the center of downtown. It was originally designed to carry 75,000 vehicles per day and today it carries over 200,000 vehicles per day. The traffic is slow, accident rates are high and the problem is escalating making it one of America’s most congested highways. In addition this elevated highway has segregated the historic North End of the city and waterfront area from the rest of the downtown area limiting their ability to participate in the economic life of the rest of the city.
The project has been under construction since late 1991. A bridge across the Charles River was opened in the Fall of 1999. The I-90 extension through South Boston to the Ted Williams Tunnel and Logan Airport will open in September 2002. The northbound lanes of the underground highway replacing the Central Artery will open in November 2002 and the southbound lanes in November 2003. The entire project will be finished in 2004, including the demolition of the existing highway and restoration of the surface.
FOAM-TECH’S role at The Big Dig
The tunnel construction method being used consists of ground-freezing technology. The strength of frozen ground is usually higher than concrete and it is impermeable which makes it highly effective in shoring applications where there is a high water table with wet loose soil. Freezing the ground stabilizes the caving soil and prevents groundwater seepage into the excavation sites. It eliminates the need for dewatering, it is easily installed and can be completely removed after construction, returning the site to its pre-existing condition. It is cost effective and environmentally safe.
Once the ground has been frozen and the excavation begins, FOAM-TECH technicians spray-apply a minimum of 4” of polyurethane foam onto a layer of chicken wire that has been closely installed to the frozen, freshly excavated earth walls. This layer of insulation keeps the earth frozen at the excavation site. This prevents the soil from thawing and caving into the excavated area. This is especially important to maintain a firm, usable surface at the rim of the site, preventing cave-ins and groundwater seepage. The FOAM-TECH polyurethane foam assures the effectiveness of the ground-freezing technology.
For a photo essay of the project, please see the Big Dig case study
