Boston Unclogs its Central Artery

edited by Larry Flynn / December 28, 2000

Built in1950, the Central Artery (I-93), a six-lane elevated road in downtown Boston carries more cars per lane
than any other highway in the U.S. Originally designed for 75,000 vehicles, nearly 200,000 drive this overcrowded
road each day. That means four to five hours a day of bumper-to-bumper, stop-and-go traffic.

Boston's Logan Airport is just one mile from downtown. Yet it takes an hour or more of driving time through two aging
tunnels to get to the airport.

The existing Central Artery and surrounding streets are presently heavily used. So, city fathers, in planning the major
construction required, made sure that traveling to work and businesses as well as Boston's historic sites would not be

To prevent service disruption, hundreds of miles of gas, telephone, electric and sewer lines were moved out of the path
of the new underground highway. This has helped prevent service interruptions and permitted the utility companies to
upgrade services, make maintenance easier and increase future capacity and reliability.

When the underground highway is completed, the present six-lane highway will be removed.

Daily scheduling

To keep this mammoth construction project on schedule, contractors were provided a scheduled time of day they would
be permitted to move their equipment so that a near normal traffic flow could be maintained.

Boston Sand & Gravel, a major ready-mix supplier for the Boston area for more than 75 years, uses late-model,
high-performance equipment to deliver concrete, which is a highly perishable product with a 90 minute rejection
life from batch to discharge time. To adhere to this schedule, Boston Sand is utilizing late-model Mack MR trucks.
The Mack MR trucks are traditionally used as a refuse chassis providing heavy-duty service and maneuverability for
urban operations.

These trucks have been spec'd with Neway AD-246-252 heavy-duty drive axle air suspensions designed for both off-road
and on-road operation. The Neway suspensions are capable of handling a total weight capacity of 52,000 lb on the rear

Bill McGrath, operations manager for Boston Sand says, "We have already made many, many deliveries to these various
Big Dig projects. We believe we have spec'd out the right equipment for maximum efficiency and return on our

According to Dennis McNutt, who helped Boston Sand spec its new trucks, "We had reservations about an air ride
suspension, which was used for the first time on these Mack trucks. We went ahead because of all the plus benefits
we expected to receive: an easier and more comfortable ride for the drivers, less stress on the vehicle than walking
beam suspensions, possible reduced maintenance costs, easier on the mixer, less fatiguing to our drivers, and
protection for the vehicle at the same time."

When completed in 2004, the downtown Central Artery will comfortably accommodate more than 250,000 vehicles a day.

Ted Williams Tunnel

The first completed part of the Central Artery/Tunnel Project was opened to commercial traffic on Dec.15,1995
(see Steel Fabrication Floats Williams Tunnel, November1996, p 30). The three-quarter mile Ted Williams Tunnel
connects South Boston to Logan Airport.

Simultaneously, in South Boston and at Logan Airport, the land-based tunnels carrying traffic in and out of the
underwater tunnel were built.

On weekdays, the tunnel carries only commercial traffic. On weekends, the tunnel is open to all vehicles. Because
they are most affected by artery construction, residents of Boston's North End, South End, and East Boston can use
the tunnel at any time. In 2001, the tunnel will open to all vehicles.

Charles River Crossing

The underground Central Artery will surface near Boston's North Station, crossing the Charles River with a dramatic
new cable-stayed bridge. The new bridge will carry10 lanes of traffic, double the present bridge's capacity. Work on
the new bridge was started early this year.

Boston in the 21st century

When the Central Artery/Tunnel Project is completed, the future holds all these benefits not only to Boston, but
all of New England:

  • I-93, the downtown Central Artery, will be able to carry more than 250,000 vehicles a day;
  • Using eight to10 traffic lanes, compared to six on today's elevated highway, there will be fewer on and off ramps, and a new network of surface streets. Through traffic will be greatly speeded up. Local traffic will be distributed at street level rather than having to "lane hop" for position on the highway;
  • The Ted Williams Tunnel will be able to carry more than 90,000 vehicles per day compared to 20,000 today with limited access;
  • There will be air improvement for the area, carbon monoxide levels will be reduced12%, because traffic will be moving rather than grid locked;
  • The ugly elevated highway will be replaced by 27 acres of new, open space along the artery corridor; and
  • Cross streets between downtown, the waterfront, and the North End, now severed or disrupted by the present elevated highway, will be reconnected.

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