Massachusetts Turnpike Authority
Tunnels and Bridges
Tunnels and Bridges
The Central Artery/Tunnel Project opened three major highway tunnels and an innovative river crossing. Engineering Marvels describes our varied construction techniques and engineering feats for tunneling and bridge building in a dense urban environment. Each category below describes the major underground features of the new highway system and the crossing.
The Ted Williams Tunnel
The Ted Williams Tunnel (TWT) beneath Boston Harbor - the first completed milestone
of the Central Artery/Tunnel Project - opened on schedule and within its $1.3
billion budget on December 15, 1995.
Named for the legendary Boston Red Sox baseball player, the tunnel doubles Boston's cross-harbor tunnel capacity from four lanes to
eight. (More)
The Charles River Bridges
The underground Central Artery surfaces near the Fleet Center at Causeway Street
and crosses the Charles River on an elegant 10-lane, cable-stayed bridge. The
bridge, called the Leonard P. Zakim Bunker Hill Bridge, is the widest cable-stayed
bridge in the world, and the first in the United States with an asymmetrical,
hybrid design. The bridge has opened in stages. Four lanes of I-93 Northbound
were opened to traffic in March 2003. Four lanes of I-93 Southbound were opened
in December 2003, with the remaining two lanes schedule to open in early 2005.
Even before it opened, the bridge was recognized as a spectacular new landmark
gateway to downtown Boston. (More)
The I-90 Extension 
The Massachusetts Turnpike (I-90) Extension opened to traffic on January 18,
2003. Now, I-90 runs from Seattle, Washington to Logan International Airport in
East Boston. In Massachusetts, the MassPike now runs 138 miles from the New York
border to Route 1A in East Boston.
As a result of the extension commpletion, the MassPike runs from its previous
terminus at I-93 near South Station to underneath railroad tracks, the Fort Point
Channel and South Boston before connecting to the Ted Williams Tunnel. Motorists
from south and west of Boston have for the first time received direct access to
Logan Airport and Massachusetts' North Shore via I-90 eastbound.
This direct, 3.5 mile route to the airport saves drivers as much as 45 minutes
off the previous route, which involved leaving the MassPike, merging onto the
old Central Artery northbound and then exiting in the North End to take the Callahan
Tunnel to Logan.
The new I-90 interchange in South Boston also provides direct access to the center
of a vital new development area for the Boston seaport, which features the newly
opened Massachusetts Convention Center.
The construction of the I-90 Extension involved some of the most complicated
and challenging engineering on the Central Artery/Tunnel Project. It required
tunnel jacking, the construction of a casting basin for immersed tube tunneling and cut-and-cover tunnel construction.
The Thomas P. O'Neill, Jr. Tunnel (I-93 tunnels)
The Thomas O. O'Neill, Jr. Tunnel (I-93 tunnels), 1.5 miles of underground roadway
from Kneeland Street to Causeway Street that connect to the Leonard P.Zakim Bunker Hill Bridge, opened in 2003. The northbound side opened to traffic on March 29 and the southbound
side opened on December 20. See our Maps page for details.
The reconstruction of I-93 through downtown Boston was enormously complex. Before
heavy construction began, utilities had to be relocated and mitigation measures put in place. Then slurry wall construction began in the mid-1990s, which required underpinning of the existing elevated Central Artery before excavation.
Once I-93 North opened under the footprint of the elevated Central Artery, Big
Dig crews began demolishing the aging elevated highway. That work was finished
in 2004, after southbound traffic was also shifted underground and the Artery
became devoid of vehicles for the first time in half a century.
