Big Bridge, Little Bridge: the big dig soars across the Charles River - includes related article on the Central Artery/Tunnel project - two new bridges across the Charles River in Boston, Massachusetts - Cover Story

Public Roads, Sept-Oct, 1999 by Sybil Hatch

Other Central Artery/Tunnel contracts also incorporate material from various states. Most notably, structural steel is being fabricated or fit up in Alabama,Arkansas, California, Colorado, Connecticut, Florida, Georgia, Kentucky, Maine, Maryland, New Hampshire, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina,Texas, and Virginia. In addition, other project elements have varied points of origin: ventilation fans from Ohio, ceiling panels from Oklahoma and Vermont, tiles from Indiana and North Carolina, and temporary bridge elements from New York.

Furthermore, a precast concrete plant has been established in Sanford, Maine. This plant, which was converted from a vacant, pre-World War II airport hanger, was established specifically for a Central Artery/Tunnel contract, but it will continue to cast segments for other construction contracts around the country.

And the project's solid foundation, upon which all decisions and actions are based, is the team relationship between FHWA, MTA, Bechtel/Parsons Brinckerhoff, and Atkinson-Keiwit.

"Good communications is the key to teamwork and a successful job,' noted MacPhail. "Everyone who is working on this project, from the laborers all the way through the management team, has an immense sense of pride at building such a challenging and significant project."

Revolutionizing Boston

The Central Artery/Tunnel project is the largest, most complex, and technologically challenging highway project ever attempted in American history. The project, in essence, will replace the existing I-93 elevated highway with an underground expressway and will extend I-90 to Logan Airport.

The project will dramatically reduce traffic congestion and improve mobility in one of America's oldest and most congested major cities, improve the environment, and lay the groundwork for New England's continued economic growth. Traffic on I-93 now crawls for more than 10 hours each day. The accident rate on the deteriorating highway is four times the national average for urban interstates. The annual cost to motorists from this congestion - in terms of an elevated accident rate, wasted fuel from idling in stalled traffic, and late delivery charges - is estimated at $500 million.

The project spans slightly more than 12 kilometers of highway with about 260 lane-kilometers in all and with about half of that in tunnels. The Central Artery/Tunnel project will place 2.9 million cubic meters of concrete and excavate almost 10 million cubic meters of soil - thus the nickname "The Big Dig," evoking memories of the Panama Canal, "The Big Ditch." The larger of the two Charles River bridges, a 10-lane cable-stayed bridge, will be the widest ever built and the first to use an asymmetrical design.

Major challenges for the project's designers and builders include difficult soil conditions, tight working space, the proximity to huge glass-and-steel office towers and fragile old brick buildings, the need to hold up an elevated highway while tunneling directly beneath it, and keeping Boston open for business throughout 14 years of construction.