Big Dig

The Big Dig (about: " The Great Divide " ) was an urban planning project in Boston, with the most widely used urban highway of the city, which was John F. Fitzgerald Expressway, laid in a tunnel. Officially known as the Central Artery / Tunnel Project ( CA / T) designated and since 1982 designed and built Lowering the central city motorway, connected to a new underground crossing of the Charles River was one of the most complex civil engineering projects in the world.

At the peak of construction 5000 workers were employed with the Central Artery project. 2004, the stilts motorway to be reduced. Was built and is (with over 80 percent of federal funds ) a technocratic compromise. The deep- down city motorway is now designed to 240,000 vehicles per day, ( still in work) interface design has failed a little less green than they had imagined environmentally moving citizens' initiatives. The urban implications, but as positive. In particular, as was the isolation Boston be removed from its successfully revitalized in recent decades Waterfront. Currently ( early 2007 ) are completed 98 percent work on the Central Artery project. The total cost will be on the current release of the Massachusetts Turnpike Authority to $ 14.6 billion, which is more than five times the original target of $ 2.6 billion. The open spaces obtained by the lowering of the city highway will be about eleven acres, the carbon dioxide burden Boston expected to reduce the building by about twelve percent.

Historical Background

Boston branched roads were created long before the advent of the automobile. In the mid-20th century, the automobile quantities introduced into the streets of downtown to traffic on a regular basis to a halt. The Commissioner of Public Works, William Callahan, submitted plans for an elevated road, which was finally built 1951-1959 between downtown and the waterfront.

The Central Artery was built before the strict Interstate Highway standards were developed under the Eisenhower administration. Therefore, the highway of sharp turns, excessive number of entrances and exits and entrances without trace was characterized for ranking.

Early planning

A lowering of the six-lane Central Artery was intensively discussed since the 1970s. The designed for a capacity of 75,000 cars per day high road was hopelessly overloaded with over 200,000 cars per day, also showed the steel support structure significant fatigue. A gradual renovation of the existing building and the associated traffic delays would impose a total years of traffic chaos in downtown Boston.

Furthermore, the negative effects of urban stilts highway designed specially in potentially high-priced, urban of locations near a tunnel solution. With the redesign of the " main artery " of individual finally joined environmentally committed the hope of a renewed, greener city and the Boston architectural community hope for increased works in the vacant central locations. Also a direct motorway connection should be created under the river to the city's airport.

Preliminary planning

Planning for the project began officially in 1982, the environmental impact studies in 1983. After years of extensive courtship for federal funds, passed in 1987, a financial plan to the U.S. Congress, but this was rejected by President Ronald Reagan as being too expensive. When Congress repealed Reagan's veto, the project had the green light and the base for ground breaking in 1991.

Obstacles

In addition to the financial difficulties, the project was compared to several environmental and engineering obstacles. The reason the city center, through which the tunnel should be excavated, consisting mostly of landfill. In addition, a subway is crossed and it had to be replaced or moved countless pipes and manholes.

The workers encountered many unexpected geological and archaeological barriers of Eisschutt on foundations of buried houses to several sunken ships that lay in the construction zone.

Only with the help of sophisticated construction techniques it was possible to build such an important transport axis, without restricting the flow of traffic excessively. So diaphragm walls were founded in more than 36 meters deep, which intercepted the masts of the existing motorway route during the construction period and the entire excavation stabilized.

Another obstacle was the South Station, the seven tracks are used daily by 400 trains and more than 40,000 commuters. Instead, as planned initially the tracks to pivot multiple times, instead they built here a special Abfangkonstruktion under which the highway tunnel was dug through it. In addition, the ground was icy to further enhance stability in the vicinity of the excavation.

For the intersecting subway tunnel an underground concrete bridge was built, which was based on the foundation pit and intercepted it and then stabilized.

Construction phase

The main project of the Central Artery Tunnel project was conducted in the design and construction of the Massachusetts Turnpike Authority and monitored by a joint venture of Bechtel Corporation and Parsons Brinckerhoff. Because of the enormous size of the project that exceeds the capabilities of any single company wide, the Big Dig were split into dozens of smaller subprojects and distributed among several contractors.

The main contractor of the project were Jay Cashman, Modern Continental, Obayashi Corporation, Perini Corporation, Peter Kiewit Sons ' Incorporated, JF White and the Slattery division of Shanska USA. In total, Modern Continental was included most of the contracts, joint ventures.

One of the most controversial points of the overall project was the crossing of the Charles River. In particular, environmentalists called for a fully underground route, but this was rejected as too costly. When finally moved the date for the start of construction of the connection between Tobin Bridge and Charles River crossing ever closer, Salvucci flouted the objections and chose a variant of the later as " Scheme Z" became known plan. This seemed relatively cost- effective, but had the consequence that directly 30 meters would grow into the air next to the Charles River highway ramps. The city of Cambridge then protested against this blight on landscape and brought an action to revoke the environmental certificate to the project. The entire river crossing then had to be rescheduled, while the feeder to the Tobin Bridge was already under construction. The plan to eventually agreed, this piece of track then laid in a tunnel ( the so-called " City Square Tunnel" after the name of the place, which he passes under ). Costs increased by this change in the connection of U.S. Route 1 and changes considerably to the already existing tunnels.

The blue clay minerals and other soil removed from the tunnels were used to cover many local landfills, fill the Granite Rail Quarry in Quincy, and restore the surface of Spectacle Island in the Boston Harbor Islands National Park.

The Leonard P. Zakim Bunker Hill Memorial Bridge, designed by the Swiss engineer Christian Menn, was finally the end of the project, the underground city highway with I-93 and U.S. 1 to join. The distinctive cable-stayed bridge is supported by two forked associated pylons, where the cables are attached and track support.

In 1999, the Leverett Circle connectivity, a sister bridge of the Zakimbrücke taken for traffic from I- 93 to Storrow Drive into operation. This project was for many years in planning, but for a long time by the wealthy residents of Beacon Hill was fought. This resistance finally crumbled, because the only way the traffic would be channeled to Storrow Drive and downtown Boston and moved away from the inner-city streets. For connecting two ramps were used, which were originally intended for Interstate 695. This increased the capacity of the I- 93, which could also accommodate the traffic now that would have been performed according to the original plans of the I-695.

When construction starts, the project cost, including the Charles River crossing, were estimated at 5.8 billion U.S. $. During the construction phase, the cost overruns were so high that the chairman of the Massachusetts Turnpike Authority, James Kerasiotes, was released in 2000. His successor had to commit to a limit of 8.55 billion U.S. $. The total cost eventually amounted to 15 billion U.S. $.

Final phase

On 17 January 2003, the opening of I -90 connecting tunnel was celebrated, extending the Massachusetts Turnpike ( Interstate 90) east into the Ted Williams Tunnel, and onwards to Logan Airport. ( The Williams Tunnel was completed since the end of 1995 and released in limited use for trade and for high- occupancy vehicles ( vehicles with at least two people). ) The leading westward direction opened in the afternoon of January 18, the leading eastward on January 19.

The next phase, in which the high Interstate 93 should be installed under the ground was conducted in two phases. The northward leading lanes were released in March 2003, which was southward leading to a preliminary arrangement on 20 December 2003. A tunnel under the Leverett Circle, who with Interstate connects the east leading Storrow Drive 93 north and the Tobin Bridge December 19, opened in 2004, to reduce the traffic congestion occurring around the roundabout. The last leading south lanes of Interstate 93, including the left lane of the Zakim Bridge and the repaired Dewey Square Tunnel was opened on 5 March 2005 the traffic.

In September 2004 there was a flooding in the north tunnel, as a result of the tunnel had to be temporarily closed. During the subsequent investigation, the project management admitted that the tunnel over 1000 leaks had. New reports showed that even 7.2 million liters of water per month were pumped out of the tunnel in March 2007. The leaks are due to partial inferior concrete and cracks in concrete and were the reason for an action for damages against a number of construction companies.

On 10 July 2006 fell two ceiling panels with a total weight of 2.6 tons to a vehicle traveling in the tunnel car and injured the 38 -year-old female passenger Milena Del Valle fatal. The collapse took place in the Interstate 90 East tunnel at the level of D- Street. As a result of the collapse of all the ceiling tiles of the same design have been removed in the I -90 East and I-90 - West Tunnel and the I-90 tunnel was closed for several months. Exactly one year later, the NTSB published its report in which it was found that the use of low-grade epoxy resin had caused the accident in the bonding of the ceiling studs and thus existed negligence of the involved contractors. The state of Massachusetts offered the construction consortium Bechtel - Parsons Brinckerhoff on 14 July 2007 a ​​comparison that would, but for a payment of $ 1 billion by a court process. This offer was heavily criticized by the media, as in the case of a process, the punishment for Bechtel Parsons Brinckerhoff should be significantly higher.

Following extensive inspections and repairs Interstate -90 East and West routes were reopened in early January 2007.

Extensions

The project also includes the construction of the Ted Williams Tunnel as an extension of Interstate 90 to Logan International Airport, the Zakim Bunker Hill Bridge over the Charles River, and the Rose Kennedy Greenway park on the site of the previous highway. Originally, the plan included a designated as a North - South Rail Link rail link between the two main train stations of Boston.

Costs

The Big Dig is the most expensive road construction project in the United States. 1985 initially estimated at 2.8 billion U.S. dollars, amounted to the total cost by the end of 2006, more than 14.6 billion, financed by taxpayers' money the federal government and the State of Massachusetts. In the course of project implementation, there was a criminal investigation, skyrocketing costs, our inability to manage and use inferior materials. The Attorney General of Massachusetts is considering actions for damages in the amount of 108 million U.S. dollars against several contractors to reimburse the state for the bad work.

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