Gourt Home::Gourt :: Big Dig
Big Dig is the unofficial name of the Central Artery/Tunnel Project (CA/T), a massive undertaking to reroute the Central Artery (Interstate 93), the chief controlled-access highway through the heart of Boston, Massachusetts, into a 3.5 mile (5.6km) tunnel under the city, replacing a previous elevated roadway. The project also included the construction of the Ted Williams Tunnel (extending Interstate 90 to Logan International Airport) and the Zakim Bunker Hill Bridge over the Charles River.
The Big Dig is the single most expensive highway project in American history. Although the project was estimated at $2.5 billion in 1985, when the last major highway section opened in December 2003, over $14.6 billion had been spent in federal and state tax dollars as of 2006. The project has been replete with delays, arrests, escalating costs, leaks, poor execution and use of substandard materials. The Massachusetts Attorney General is demanding contractors refund taxpayers $108 million for "shoddy work."
The tunnel segment under south Boston which connects the mainline of I-90 to the Ted Williams tunnel is closed indefinitely in response to the July 10, 2006 collapse of a ceiling section that killed a woman riding as a passenger in the tunnel.
Historical background
Boston's historically tangled streets were laid out long before the advent of the automobile. By mid-20th century, car traffic in the inner city was extremely congested, with north-south trips especially so. Commissioner of Public Works William Callahan pushed through plans for an elevated expressway which eventually was constructed between the downtown area and the waterfront. This "Central Artery" (known officially as the John F. Fitzgerald Expressway) displaced thousands of residents and businesses and physically divided the historical connection between the downtown and market areas and the waterfront. Governor John Volpe interceded in the 1950s to send the last section of the Central Artery underground, through the Dewey Square (or "South Station") Tunnel, but while traffic moved somewhat better the other problems remained.
Built before strict federal Interstate Highway standards were developed during the Eisenhower administration, the expressway was plagued by tight turns, an excessive number of entrances and exits, entrance ramps without merge lanes, and continually escalating vehicular loads. Local businesses again wanted relief, historians sought a reuniting of the waterfront with the city, and nearby residents desired removal of this "Green Monster". ("Its matte green paint prompted
Cancellation of the Inner Belt
Another important motivation for the Big Dig in its final form was the abandonment of the Massachusetts Highway Department's intended expressway system through and around Boston. The Central Artery, as part of MassHighway's Master Plan of 1948, was originally planned to be (and signed as) the downtown Boston stretch of Interstate 95, with a bypass road called the Inner Belt (officially Interstate 695) to pass around the downtown core to the west, through the neighborhood of Roxbury and the cities of Brookline, Cambridge and Somerville. However, earlier controversies over impact of the Massachusetts Turnpike Boston extension, particularly on the heavily populated neighborhood of Brighton, and the large number of additional homes that would have had to be destroyed led to massive community opposition to both the Inner Belt and the Boston section of I-95.Clearances for I-95 through the neighborhoods of Roxbury, Jamaica Plain, and Roslindale led to secession threats by Hyde Park, Boston's southernmost neighborhood (and the one most recently added to the city, in 1912). By 1972, however, with only a minimum of work done on the I-95 right of way and none on the potentially massively disruptive Inner Belt, Governor Francis Sargent put a moratorium on highway construction within the MA-128 corridor, except for a short stretch of Interstate 93. In 1974 the remainder of the Master Plan was canceled, leaving Boston with a severely overstressed expressway system. With ever-increasing traffic volumes funneled onto I-93 alone, the Central Artery became chronically gridlocked. The Sargent moratorium led to the rerouting of I-95 away from Boston around the MA-128 beltway and the conversion of the cleared land in the southern part of the city into the Southwest Corridor linear park and a new right of way for the Orange Line subway and Amtrak. Parts of the planned I-695 right of way remain unused and under consideration for future mass transit projects.
The original 1948 Master Plan included a Third Harbor Tunnel plan that was hugely controversial in its own right because it would have disrupted the Maverick Square area of East Boston. It was never built.
Commingling of traffic
A major reason for the all-day congestion was that the Central Artery carried not only north-south traffic, but much east-west traffic as well. Boston's Logan Airport lies across Boston Harbor in East Boston, and before the Big Dig, the only access from downtown was through the paired Callahan and Sumner tunnels. Traffic on the major highways from west of Boston, the Massachusetts Turnpike and Storrow Drive, mostly traveled on portions of the Central Artery to reach these tunnels. Getting between the Central Artery and the tunnels involved short stretches on city streets, increasing local congestion.The final Big Dig plan, then, combined several projects—the depression and improvement of the Central Artery, the construction of a third Harbor tunnel (now known as the Ted Williams Tunnel), and massive interchange improvements to the Massachusetts Turnpike and several other major routes in the area. While only one net lane in each direction was added to the north-south I-93, several new east-west lanes were added to untangle the traffic. East-west traffic on the Massachusetts Turnpike now proceeds directly through the Ted Williams Tunnel to Logan Airport and Route 1A beyond, with new exits in South Boston along the way. Traffic between Storrow Drive and the Callahan and Sumner Tunnels uses a short portion of I-93, but additional lanes and direct connections are provided for this traffic.
Mass transit
A number of public transportation projects were included as part of an environmental mitigation for the Big Dig. Perhaps the most ambitious was the building of the Phase II Silver Line tunnel under Fort Point Channel, done in coordination with Big Dig construction. Silver Line buses now use this tunnel and the Ted Williams Tunnel to link South Station and Logan Airport. Several other mitigation transit projects promised have not been completed as of 2005 and litigation has been threatened.Yet another plan, the North-South Rail Link that would have connected North and South Stations, the major passenger train stations in Boston, was part of the original Big Dig but was ultimately dropped by the Dukakis administration as an impediment to acquiring Federal funding for the project.
Early planning
The project was conceived in the 1970s to replace the rusting elevated six-lane Central Artery. The expressway separated downtown from the waterfront, and was increasingly choked with bumper-to-bumper traffic. Business leaders were more concerned about access to Logan Airport, and pushed instead for a third harbor tunnel. In their second terms as governor and secretary of transportation, respectively, Michael Dukakis and Fred Salvucci, came up with the strategy of tying the two projects together—thereby combining the project that the business community supported with the project that they and the City of Boston supported.
Planning for the Big Dig officially began in 1982, with environmental impact studies starting in 1983. After years of extensive lobbying for federal dollars, a 1987 public works bill appropriating funding for the Big Dig was passed by U.S. Congress, but it was subsequently vetoed by President Ronald Reagan as being too expensive. When Congress overrode his veto, the project had its green light and ground was first broken in 1991.Dan McNichol and Andy Ryan, The Big Dig. Silver Lining Press, 1991
Major obstacles
In addition to these political and financial difficulties, the project faced several environmental and engineering obstacles.
The downtown area through which the tunnels were to be dug was largely landfill, and included existing subway lines as well as innumerable pipes and utility lines that would have to be replaced or moved. Tunnel workers encountered many unexpected archaeological barriers, ranging from glacial debris to foundations of buried houses and a number of sunken ships lying within the reclaimed land.
The project received approval from state environmental agencies in 1991, after satisfying concerns including release of toxins by the excavation and the possibility of disrupting the homes of millions of rats, and causing them to roam the streets of Boston in search of new housing. By the time the federal environmental clearances were delivered in 1994, the process had taken some seven years, during which time inflation greatly increased the project's original cost estimates.
Reworking such a busy corridor without seriously restricting traffic flow required a number of state-of-the-art construction techniques. Because the old elevated highway (which remained in operation throughout the construction process) rested on pylons located throughout the designated dig area, engineers first utilized slurry wall techniques to create 120 ft.-deep concrete walls upon which the highway could rest. These concrete walls also stabilized the sides of the site, preventing cave-ins during the excavation process.
Other challenges included an existing subway tunnel crossing the path of the underground highway. In order to build slurry walls past this tunnel, it was necessary to dig beneath the tunnel and build an underground concrete bridge to support the tunnel's weight.
Construction phase
The Central Artery/Tunnel Project was managed by the Massachusetts Turnpike Authority with design and construction supervised by a joint venture of Bechtel Corporation and Parsons Brinckerhoff. Due to the enormous size of the project—too large for any company to undertake alone—the design and construction of the Big Dig were broken up into dozens of smaller subprojects with well-defined interfaces between contractors. Major heavy-construction contractors on the project included Jay Cashman, Modern Continental, Obayashi Corporation, Perini Corporation, Peter Kiewit Sons' Incorporated, J.F. White, and the Slattery division of Skanska USA. (Of those, Modern Continental was awarded the greatest gross value of contracts, joint ventures included.)
The nature of the Charles River crossing had been a source of major controversy throughout the design phase of the project. Many environmental advocates preferred a river crossing entirely in tunnels, but this, along with 27 other plans, was rejected as too costly. Finally, with a deadline looming to begin construction on a separate project that would connect the Tobin Bridge to the Charles River crossing, Salvucci overrode the objections and chose a variant of the plan known as "Scheme Z". This plan was considered to be reasonably cost-effective, but had the drawback of requiring highway ramps stacked up as high as 100 feet (30 m) immediately adjacent to the Charles River.
The city of Cambridge, objecting to the visual impact of the chosen Charles River crossing design, sued to revoke the project's environmental certificate, and forced the project to redesign the river crossing yet again. Meanwhile, construction continued on the Tobin Bridge approach. By the time the I-93 design was finally settled to the satisfaction of all parties, the construction of the Tobin connector (today known as the "City Square Tunnel" after the intersection in Charlestown which it bypasses) was already so far along that significant additional expense would be incurred to stage construction of the U.S. Route 1 interchange and eventually retrofit the tunnel; in the new design, not all of the traffic movements originally envisioned would be possible.
Boston blue clay and other soils extracted from the path of the tunnel were used to cap many local landfills, fill in the Granite Rail Quarry in Quincy, and restore the surface of Spectacle Island in the Boston Harbor Islands National Recreation Area.
The Zakim Bunker Hill Bridge, designed by Swiss designer Christian Menn, represents the terminus of the project, connecting the underground highway with I-93 and US 1. A distinctive cable-stayed bridge, the crossing is supported by two forked towers, which are connected to the span by cables and girders.
The Storrow Drive Connector, a companion bridge to the Zakim that carries traffic from Interstate 93 to Storrow Drive along the Charles River, opened in 1999. The project had been under consideration for many years, opposed largely by the residents of Boston's wealthy Beacon Hill neighborhood, and finally came to fruition as a way to funnel the traffic bound for Storrow Drive and the northern part of downtown Boston away from the mainline roadway. Ultimately the Connector wound up using a pair of ramps originally constructed for Interstate 695, ironically making it possible for the mainline I-93 to carry more of the through traffic that was supposed to use I-695 in the original Master Plan.
At the time construction began, the whole project (including the Charles River crossing) was projected to cost $5.8 billion. Eventual cost overruns were so high that the chairman of the Massachusetts Turnpike Authority, James Kerasiotes, was fired in 2000 and his replacement had to commit to a cap in federal contributions of $8.549 billion. Total expenses to date have surpassed $15 billion.
The project today
On January 17, 2003, the opening ceremony was held for the I-90 Connector Tunnel, extending the Massachusetts Turnpike (Interstate 90) east into the Ted Williams Tunnel, and onwards to Logan Airport. (The Williams tunnel had been completed and in limited use for commercial traffic and high-occupancy vehicles since late 1995.) The westbound lanes opened on the afternoon of January 18 and the eastbound lanes on January 19.
The next phase, moving the elevated Interstate 93 underground, was completed in two stages: northbound lanes opened in March 2003 and southbound lanes (in a temporary configuration) on December 20, 2003. A tunnel underneath Leverett Circle connecting eastbound Storrow Drive to I-93 North and the Tobin Bridge opened December 19, 2004, easing congestion at the circle. All southbound lanes of I-93 opened to traffic on March 5, 2005, including the left lane of the Zakim Bridge, and all of the refurbished Dewey Square Tunnel.
By the end of December 2004, 95% of the Big Dig was completed. Major construction remained on the surface, including construction of final ramp configurations in the North End and in the South Bay interchange, and reconstruction of the surface streets. Many impact-mitigation projects (transit, pedestrian, bicycle, and parks) also remain, but some are in danger of cancellation due to cost overruns on the rest of the project.
The final ramp downtown—exit 20B from I-93 south to Albany Street—opened January 13, 2006.
Substandard work, criminal misconduct, and collapses
"Thousands of leaks"
As far back as 2001, Turnpike Authority officials and private contractors knew about thousands of leaks in the ceiling and wall fissures, extensive water damage to steel supports and fireproofing systems, and overloaded drainage systems. A $10 million contract, signed off as a cost overrun, was used to repair these leaks. Many of the leaks were a result of Modern Continental and other subcontractors failing to remove gravel and other debris before pouring concrete. This was not made publicly available to the media.On 2004-09-15, a major leak in the Interstate 93 north Liberty Tunnel forced the closure of the tunnel while repairs were conducted. This also forced the Turnpike Authority to release information regarding its non-disclosure of prior leaks. A follow-up reported on "extensive" leaks that were more severe than state authorities had previously acknowledged. The report went on to state that the $14.6 billion tunnel system was riddled with more than 400 leaks. A Boston Globe report, however, countered that by stating there were nearly 700 leaks in just one, 1,000-foot section of tunnel beneath South Station. Turnpike officials also stated that the number of leaks being investigated was down from 1,000 to just 500.
Substandard materials
On August 11, 2005, it was announced that the Massachusetts State Police searched the offices of the Big Dig's largest concrete supplier in June and found evidence of faked records that hid the poor quality of concrete delivered for highway project. However, it is not believed that the low-quality concrete is connected to the hundreds of leaks discovered in the tunnels that take vehicles under Boston.On March 19, 2006, the International Herald Tribune reported that Massachusetts "Attorney General Tom Reilly plans to sue Bechtel/Parsons Brinckerhoff and other companies if the two sides do not reach an agreement over 200 complaints of poor work in the construction of a highway system under the center of Boston, the Boston Globe reported Saturday. Reilly was said to be seeking $67 million from Bechtel and $41 million from other companies."
Criminal misconduct
On May 4, 2006, six current or former employees from the concrete supplier Aggregate Industries Inc. were arrested and charged for falsifying records regarding the poor quality concrete.On May 5, 2006, due to the controversy, Massachusetts Governor Mitt Romney announced he would return some $3,500 in political contributions from employees of Aggregate Industries.
Big Dig tunnel ceiling collapse
On July 10, 2006, at approximately 11:00 p.m., a steel tieback that suspends the concrete drop ceiling inside the tunnel structure failed near the eastern portal of the eastbound I-90 connector tunnel leading to the Ted Williams Tunnel in South Boston, causing four three-ton sections of ceiling to collapse. A section of ceiling fell on top of a car traveling through the tunnel, killing newlywed 38-year-old passenger Milena Del Valle and slightly injuring her husband Angel Del Valle, who was driving. The Boston Globe noted that similar tiebacks were in use in the Ted Williams Tunnel, as well as in 17 places on Interstate 90. Attorney General Tom Reilly issued subpoenas to those involved in the construction and testing of the tunnels in which criminal charges may follow. Governor Mitt Romney also returned from a vacation in New Hampshire to view the condition of the tunnels. Governor Romney and Attorney General Reilly both called for the resignation of Turnpike Authority chairman Matthew J. Amorello who provides oversight of the project. This stance was supported in editorials in Boston's two major newspapers, the Boston Herald and the Boston Globehttp://www.boston.com/news/globe/editorial_opinion/editorials/articles/2006/07/12/time_to_go/ Romney and Reilly have garnered criticism from the media for accepting campaign contributions from Big Dig contractors and for not taking more action prior to the fatal accident. Modern Continental was the contractor that built this section.
On July 12, 2006, investigators began questioning how the tunnel ceiling was constructed. The collapse of the ceiling structure began with the failure of a single steel hanger that held up the panels. The failure of that panel set off a chain reaction that caused other hangers to fail and sent 12 tons of concrete smashing below. Numerous problems with this same system of bolts and epoxy in the Ted Williams Tunnel were revealed by the state Office of the Inspector General in a 1998 report. Not only were the bolts too short, but the epoxy used to glue the bolts into the concrete was not up to standard. Safety inspections ordered in the wake of the tunnel collapse initially identified 60 potentially dangerous bolt fixtures that support the ceiling in the Interstate 90 connector tunnel. A follow-up investigation quadrupled the number of potentially dangerous bolt fixtures to 242.
On July 16, 2006 Attorney General Reilly told the press that three of the bolts that held up the three-ton concrete panel that fell did not have epoxy on them and that others showed an uneven distribution of epoxy.
As a result of the indefinite closure of the Interstate 90 connector, all surface work along the Big Dig, including the Rose Kennedy Greenway, was ordered stopped by Boston officials, to accommodate the extra traffic that normally would use the closed tunnel.
On July 13, 2006, the leaders of the state legislature, Senate President Robert Travaglini and House Speaker Sal Dimasi called upon Turnpike Authority chairman Matthew J. Amorello to consider stepping down from his position and accepting a diminished role. The legislature approved the governor's plan to assume oversight of the investigation into the collapse, taking it away from the Massachusetts Turnpike Authority and to also allocate $20 million for a "stem to stern" safety review of the Central Artery system. At the request of the all the members of the Massachusetts congressional delegation, the National Transportation Safety Board dispatched a six-member civil engineering team to Boston to inspect the accident scene and determine whether a full-scale investigation is warranted.
The state Turnpike Authority (citing the existence of an ongoing criminal investigation into the tunnel ceiling collapse) and the Federal Highway Administration have refused requests to release documents relating to the work conducted along the Seaport connector, including:
- Deficiency reports that would have shown problems flagged during initial work on the tunnel.
- Construction change orders that would have shown costly repairs and contract revisions that occurred because of deficiencies.
- Inspection reports and other documents that would show who would have knowledge of the workmanship and building material quality.
Likewise, just one year earlier, U.S. Representative Stephen Lynch had trouble obtaining records regarding the Big Dig tunnel leaks for the Congress' Committee on Government Oversight.
References
External links
- Washington Post "Boston's Big Dig Awash in Troubles" November 19, 2004
- Official site
- Boston CA/T Project History at MIT Rotch Library
- Steve Anderson's BostonRoads.com
- PBS.org – Central Artery
Tunnels in Massachusetts | Transportation in Boston | U.S. Route 1
"Big Dig"