• Visit our partners: Our Partners:
  • Visit our partners: Our Partners:

The Big Dig: An Unending Stream of Mishaps

No country on Earth has embraced the automobile quite like the United States. Road trips along vast open highways in a top-down convertible, with the wind blowing through your – um, well anyway – has become the stuff of American legend. Yes, this free-spirited sense of abandonment is glorious on the open plains of the West – but not so much sat in grid-locked traffic in a city designed well before the automobile. What took place in Boston between 1992 and 2007 was one of the most significant, costly and ambitious redesigns of an urban landscape the country had ever seen – and it was called the Big Dig.  

The Central Artery/Tunnel Project, commonly known as the Big Dig, was a titanic undertaking and at its completion, it had become the most expensive highway project in the United States. This project of tunnels, bridges, transportation improvements, green spaces and much more, was vast. In total, the Big Dig consisted of 118 separate construction projects throughout the city of Boston. 

But it certainly wasn’t smooth sailing. The project was plagued with so many issues it was difficult to keep up. From leaks to accidental deaths – from the substandard quality of some of the work to environmental concerns, the Big Dig was an enormous headache. But on such a scale, how could it not be?  


Boston, with its storied connection to the past, is perhaps the most European, and dare I say, old fashioned city in the United States. A charming place with quaint cobblestoned streets filled with historic red brick houses, where history feels that much closer. Yet this idyllic view of Boston that many have, is also mixed with the scourge of most large cities – traffic.   

By the late 1980s, history had caught up with Boston – or rather the car finally had. The raised expressway that barrelled noisily through the centre of the city was a hellish experience. The infrastructure was simply unable to keep up with the rapid rise in vehicle numbers that choked parts of the city.   

Traffic Jams 

As early as the 1930’s city planners had suggested some kind of project to alleviate increasing traffic congestions on the city streets. Like many historic urban areas, the roads had been planned and constructed well before the notion of the automobile. What had been first set out for horses and carts, was now asked to funnel modern transportation. Unsurprisingly, like many old cities, it struggled.  

Initially, an elevated highway was constructed between Downtown and the Waterfront, with a late alteration to the project meaning a section of the highway passed instead through the Dewey Square Tunnel. This alleviated some of the pressure, but such was the expansion in automobile numbers that even this addition eventually descended into snarled traffic. To give you an idea of numbers, in 1958, approximately 75,000 vehicles used the 1.5 miles (2.4km) Central Artery per day. But by the 1990s that number had swelled to over 190,000 per day. It wasn’t uncommon for it to be badly congested for up to ten hours a day, and had a traffic accident rate four times higher than the national average. It was estimated that this was costing the public $500 million per year in lost hours. Dire predictions of traffic jams of up to 16 hours per day by 2010 meant that something had to change.

The Plan 

What was conceived was ambitious. The major aspect of the plan was to essentially move the elevated expressway underground through a tunnel that would follow the same path, with an additional tunnel to alleviate the traffic heading to and from Boston Logan Airport. The problem was that even though the I-93 ran North to South, the city was designed in such a way that much of the traffic heading East to West needed to use it also, at least partially. 

Boston's highway system before and after the Central Artery/Tunnel Project
Boston’s highway system before and after the Central Artery/Tunnel Project by MrJARichard is licensed under CC-BY

But as I’ve said, the Big Dig was so much more than just a tunnel. Though the Thomas P. O’Neill Jr. Tunnel would be the focal point of the project, it would also include the Ted Williams Tunnel (that extends I-90 under Boston Harbor to Logan International Airport, the Leonard P. Zakim Bunker Hill Memorial Bridge over the Charles River, and the Rose Kennedy Greenway, which would replace the old raised expressway. But there were countless other smaller projects mainly involving the expansion, or improvement of the public transportation network. This wasn’t simply making a few alterations here and there, it was a radical redesign of one of America’s most historic cities, to better adapt it for the 21st Century

A Logistical nightmare 

Planning for the enormous project began in 1982, and it’s fair to say obstacles were there from day one – in fact, work would not begin on the Big Dig for nearly ten years. The biggest and most immediate problem was money. Initial estimates placed the cost at $2.8 billion, and planners believed the project could be completed by 1998. Not to give too much of the game away, but both of these predictions proved to be wild underestimations. 

In 1987 a bill passed through the U.S Senate to fund the project, and although it was vetoed by President Ronald Reagan on the grounds of cost, the Senate was able to override the veto and preparation began.

The next major hurdle was how they could construct the tunnel system without causing significant delays to the already inflamed traffic above. Remember the purpose was to ease traffic, I’m not sure how the feisty Bostonians would have reacted if they had faced nearly twenty years of massive delays.

To get around this some rather ingenious methods were used. The existing raised expressway rested on pylons for support, no surprise to hear that these pylons were located exactly where they would need to build the tunnel. As a consequence, they needed to build an entirely near support system for the expressway before even commencing tunnelling.  

This was done by constructing a 37 metres (120ft) deep concrete wall using a slurry technique, which is a way of building walls in soft earth conditions, often near water. This was constructed below the expressway which could now rest upon it. 

The area was also home to not only the Red and Blue lines of the Boston Subway but also needed to pass under a seven-track railway line leading into South Station. This railway line posed a serious problem with a fear that the tunnel below could cause the lines to collapse, especially at busy hours with 400,000 commuters and 400 trains passing through a day. This would be the largest tunnelling project below existing railway lines anywhere in the world. Initial plans had called for large scale re-routing of train traffic, but this idea was scrapped, and instead, engineers used specially designed jacks to support the ground and train tracks while excavation work went on beneath them. 

Then there were the environmental concerns, which were perhaps best encapsulated by the fear that construction work could disturb Boston’s rat population underground, forcing them up to the surface, where they would presumably take over and slowly eradicate humankind. 

That last part might have just been my imagination, but you never know. In short, even before construction began on the Big Dig engineers and planners had faced a catalogue of issues, surely construction itself couldn’t be any harder?

Construction Begins

Construction finally began on this long drawn out project in September 1991 on the first bypass through South Boston. 

Even after this point, the project was still in flux. The biggest example of this was how to cross the Charles River, with a total of twenty-eight designs being rejected for numerous issues. Environmental activists were eager for a tunnel, but this was deemed far too expensive.

Eventually, planners decided on a design that would have meant highway ramps as high as 30 metres (100ft) next to the river. The City of Cambridge, which lies directly across the river, understandably baulked at such an eyesore and sued for a change in design – which they won. 

Christian Menn, a Swiss engineer, was given the task of designing a bridge that would span the river. He proposed a cable-stayed bridge – which involved one or more towers and cables that support the bridge itself. The design was accepted, and construction began on 1st October 1997. It is a beautiful addition to the Boston skyline. At 436 m (1,432 ft) in length, it doesn’t even make it into the top 50 longest cable-stayed bridges in the world, but at 56 m (183 ft) it was at the time the widest. It was constructed using 1,820 miles (2,929km) of steel and just to make sure everything was safe, on 14th October 2002, around five months before its opening, fourteen elephants borrowed from the Ringling Brothers and Barnum & Bailey Circus, weighing a total of 112,000 pounds (51,000 kg) walked across it. Apparently, in the 19th century, this was a common method to test new bridges, but one we just don’t see much of these days. 

Unsurprisingly the tunnel systems provided the biggest challenge. The soft earth, mixed with landfills that sometimes dated back hundreds of years, proved a real headache to drill through. As a result, much of the tunnel was dug again using the slurry technique meaning that a small tunnel was dug then expanded horizontally to minimize risk. 

Digging under such a modern metropolis was always going to be tough. During construction, 29 miles (46.7km) of utility lines had to be moved, but that pales in comparison to what was added. 5000 miles (8,047km) of fibre optic cables and an astonishing 200,000 miles (321,868km) of copper telephone wiring was also installed beneath Boston during the Big Dig. 

In total, 12.2 million cubic metres (16 million cubic yards) of soil was removed during the project, that’s enough to fill your average sports stadium to the rim a staggering 16 times. Much of this soil was re-used, either to fill landfills around New England or to resurface Spectacle Island, which lies in Boston Harbor, with as much as eight feet dumped in some areas on the island as a way of restoring it from weather damage. 

In terms of concrete used, it was equally astonishing. The 2.9 million cubic metres (3.8 million cubic yards) used during the project would be enough to build a pavement, three feet wide and four inches thick that would stretch from Boston to San Francisco six times.

The project was officially completed in 2007, though by 2001 nearly 70% of work, and the largest inidiviulal projects, had already been finished. At its peak, the project employed 5000 workers, producing about $3 million worth of work per day.      


Where do we even start? This was a project with a whole host of problems that sprung up either during construction or since completion. It’s easy to single out problems on these kinds of projects, the very nature of their size typically makes them ripe, however, the Big Dig experienced more than its fair share. The Boston Globe reported that during the project a total of $1 billion was lost because of design flaws. 

Let’s start with the leaks – of which there were hundreds, if not thousands. As early as 2001 those involved were said to be aware of leaks throughout the tunnels, but the information was not made public until a group of MIT researchers discovered them. Much of the blame was attributed to contractors who had failed to remove gravel and debris before pouring concrete. It was an embarrassing admission, especially with newspapers reporting 700 leaks in a single 1,000-foot (300 m) length of tunnel. 

This murky quagmire became even worse when in 2005 Massachests police raided the offices of Aggregate Industries, who had provided much of the concrete for the project, in the belief that they had knowingly supplied sub-standard materials. The following year, six employees were arrested and charged with defrauding the United States. In 2007 the case was settled for $50 million, with an additional $500,000 set aside to inspect areas thought to contain the poor quality concrete. 

While there were obvious flaws, the project had so far escaped any serious incidents – but that changed on 26th July 2006. Concrete panelling weighing an estimated 24 tonnes fell and landed on a car travelling on a two-lane ramp connecting northbound I-93 to eastbound I-90 in South Boston. The impact killed a female passenger, and badly injured the driver. A full investigation and safety audit was ordered by Governor Mitt Romney, and it was not until June the following year that all sections of the Big Dig project finally re-opened. 

The cause of the accident was the epoxy glue which had been used to fix the panels. This type of adhesive had been originally designed for shorter lengths of time. Powers Fasteners, who made the glue, agreed on a settlement that totalled more than $28 million. 

Another aspect of the project which quickly became infamous were the so-called Ginsu guardrails. These safety rails with squared-off edges were eventually blamed for as many as 8 deaths involving a passenger being ejected from a vehicle after a crash and hitting these posts. Ginsu was a brand of knives advertised on television during the ’70s and ’80s, the nickname given to these supposed “safety features” shows just how dangerous they could be. These were finally removed, but only on the curved sections.       

The Finished Product

After all of that, you’re probably wondering whether it was all worth it. That, of course, depends on who you talk to. At first glance, the ballooning costs, amateurish mistakes and incompetence might make it a little difficult to view this as a success. 

Some have argued that the situation has just pushed the traffic jams out to the suburbs and whether, with the climate change situation being what it is, the city should have encouraged road users instead of investing more in public transportation.

Mid-day traffic on Boston's elevated Central Artery (since demolished) in 2003
Mid-day traffic on Boston’s elevated Central Artery (since demolished) in 2003 by ArnoldReinhold is licensed under CC-BY-SA

Then there’s the final cost. Remember it was originally budgeted at $2.8 billion, but its cost in 2007, when construction ceased. was in the region of $14.6 billion. However – with interest that is still being paid – it’s thought that the final cost will be around $22 billion and won’t be fully paid until 2038. But did it achieve what it was designed to do?  

Mostly, yes. The congestion problems in and around central Boston have undoubtedly improved. The area has seen a 12% decrease in carbon monoxide since the completion of the project and a 62% reduction in vehicle hours of travel on I-93 – from 38,200 hours per day before the project to 14,800 per day after.

The goal was always to adapt Boston to the demands of the 21st Century, and for better or worse, it has done that. The dynamic of the city has completely changed without the noxious raised expressway creeping overhead. The green belt of parks and communal areas has transformed the city and added 27 acres of much needed open space in the downtown area.   

The Big Dig in many ways has been overshadowed by its problems, but the way it was able to remodel Boston is undeniably impressive. It would take a die-hard cynic to say it hasn’t led to improvements. With spiralling numbers in our urban areas, there is an increasing need to address the issue of traffic congestion and pollution in our cities. Whether this is done with better roads or better public transportation remains to be seen. We are quick to demand peace, calm and beauty in our cities, but as long as our lust for the good old automobile continues to grow, we will continue to need projects like the Big Dig. It wasn’t easy or cheap – and the name mentioned in a Boston bar will likely be met with grumbles – but when our way of life demands so much, what other option do we have? 

Related Articles


Please enter your comment!
Please enter your name here

Stay Connected


Random Article


Salisbury Cathedral: Gothic Home of the Magna Carta

Ninety miles south-west of London sits the small town of Salisbury, England. The town has just 30,000 inhabitants, but its most famous resident is,...

Latest Articles