7 Big Facts About the "Big Dig"

The "Big Dig" was the largest, and most expensive, highway project of its kind in the United States.
Christopher McFadden

The highly ambitious "Big Dig" project in Boston, Massachusetts turned out to be one of the most expensive and extensive of its kind in U.S. history. Work began in the 1990s but wasn't completed until the mid-2000s at a cost far in excess of what was predicted.

Here we take a quick look at the project and check out some of its vital stats.


What is the "Big Dig"?

The "Big Dig", officially called the Central Artery/Tunnel Project (CA/T), was a largescale civil engineering project in Boston. Planning began in the early 1980s with the project finally being completed in 2007.

The project involved the reroute of the Central Artery of Interstate 98 (I-93) through the city into the 1.5 miles (2.4 km) Thomas P. O'Neill Jr. Tunnel. The "Big Dig" also involved the construction of the Ted Williams Tunnel (that extends I-90 to Logan International Airport,  the Leonard P. Zakim Bunker Hill Memorial Bridge over the Charles River, and the Rose Kennedy Greenway in the space vacated by the previous I-93 elevated roadway.

The Rose Kennedy Greenway is an approximately 1.5 miles (2.4 km) series of parks and public spaces that fill in the space left by I-90 being relocated underground. It was named in honor of the Kennedy family's matriarch Rose Fitzgerald Kennedy and was officially inaugurated in 2008.

The initial plans for the project also included the construction of a rail connection between Boston's two major train terminals but this was never realized. It was the most expensive highway project ever undertaken in the U.S. at the time and was famously plagued with cost overruns, delays, leaks, and myriad other problems. 

It was originally scheduled for completion in the late 1990s and had initially been budgeted at a total cost of around $3 billion. However, as we have already touched upon, the project wasn't completed until late 2007 and its cost ballooned.

The project also claimed some lives with one motorist sadly being killed as a direct consequence of the project. In 2006 a woman motorist was crushed to death after four large concrete slabs (each weighing 3 tons) fell from the ceiling of the tunnel between the city and Logan International Airport.

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It has since been estimated that the project will ultimately cost $22 billion including interest and will likely not be fully paid off until 2038. Because of the project's serious mismanagement, associated deaths, leaks, and other design issues, the project's main consortium, Betchel, and Parsons Brinckerhoff, agreed to pay $407 million in compensation.

 Other smaller contractors associated with the works also forked out $51 million.

What was the purpose of the "Big Dig"?

The "Big Dig", as we have already seen, was the largest and most challenging highway project in United States History at the time. It was conceived to help reduce traffic and improve mobility in Massachusetts (one of America's oldest and most congested major cities).

It was also hoped that the project would build a framework for future growth in the city and New England in general. The "Big Dig" was also designed to help protect and improve the local environment.

At this time, Boston was infamous for its "world-class" traffic problem on the Central Artery. This was, at the time, an elevated highway that ran through the center of downtown Boston.

It was first opened in 1959 and had been designed to handle around 75,000 vehicles per day. Car use had ballooned in the intervening years and by the early-1990s it struggled to convey somewhere in the order of 200,000 vehicles a day.

It had, unsurprisingly, become one the most congested highways in the continental U.S. The highway was highly congested for more than 10 hours a day and accident rates were 4 times the national average.

facts about big dig
Source: Robbie Shade/Flickr

This had been projected to increase to around 16 hours a day by 2010 and was costing motorists around $500 million in lost time a year from accidents, waster fuel, and late deliveries. The highway's construction had also displaced 20,000 residents and was beginning to impact the local neighborhoods' ability to take part in the city's growing economy. 

Something had to be done. 

"The project replaced Boston's deteriorating six-lane elevated Central Artery (I-93). It did so with an underground highway that is state of the art and two new bridges over the Charles River. It also extended I-90 to Boston's Logan International Airport, and Route 1A. This project created more than 300 acres of open land while reconnecting downtown Boston to the waterfront.

When planning for the CA/T Project began in 1982, experts could not have predicted the challenges that lay ahead from design to construction. Congress approved federal funding and the project's basic scope in April 1987." - mass.gov. 

"Ground was broken" in September of 1991 on the first bypass through South Boston. This took traffic off neighborhood streets. 

A third tunnel to cross the Boston Harbor was also started at this time. 

"The first major milestone was the opening of the tunnel. Named for baseball legend Ted Williams, majority completion occurred January 13, 2006. Three major milestone openings took place in 2003." - mass.gov. 

How expensive was the "Big Dig"?

According to local sources like Boston's WBUR, the total cost for the "Big Dig" was an estimated $24.3 billion. This makes it one of the most expensive highway projects of all time in the U.S.

To put that into perspective, courtesy of WBUR, here are some other largescale projects that were actually cheaper: 

1. Hubble Space Telescope - Estimated cost $4.5-$6 billion.

2. Large Hadron Collider - Estimated cost $6 billion.

3. Airbus A380 Development - Estimated cost $15 billion.

4. Eurotunnel's Channel Tunnel - Estimated cost $21 billion. 

7 takeaway facts about the "Big Dig"

So, without further ado, here are 7 interesting facts about the "Big Dig". Any specific figures quoted below have been sourced from Massachusetts' official webpage. 

1. The "Big Dig" was conceived to relieve local congestion problems on Boston's  Central Artery (I-93) highway. It was also designed to help improve the local environment and promote economic growth in the city and state. 

facts about big dig i-93
Source: Rene Schwietzke/Flickr

2. Planning began in 1982 with the works projected to be completed in the mid-to-late-1990s. The project overran and was plagued with issues including the death of a motorist. All of this eventually resulted in the budget ballooning and it finally being finished in 2007. 

3. The project required the large-scale relocation of underground utilities. This involved moving 29 miles (46.7 km) of utility lines. New utilities were also installed including 5,000 miles (8,047 km) of fiber-optic cables and 200,000 miles (321,868.8 km) of copper telephone cables. 

4. As a result of the project's completion, an estimated 12% drop was observed in the city's carbon monoxide levels. 

5. The project's cable-stayed bridge across the Charles River consumed 1,820 miles (2,929 km) of steel wire and 150 cranes were used project-wide. 25% of the project's construction time was completed in the first 5 years with total construction reaching around 94% complete by 1994. 

6. At the peak of construction, over 5,000 workmen were on site with them completing around $3 million worth of work per day. 

7. The "Big Dig" grand project included no less than 118 separate construction contracts. 26 of these were for geotechnical drilling contracts alone. 

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