The Big Dig

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The Big Dig

• Tunnel Failure in Boston, Massachusetts

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Outline for our Presentation

• What is the Big Dig and some other general facts
  about it
• Planning for the project and what it took to
  start it
• The construction and various problems it had

3
What is the Big Dig?

• The Central Artery/ Tunnel Project (unofficially
  known as the Big Dig) was a huge project that was
  designed to reroute Interstate 93 (The main
  highway in Boston) into a 3.5 mile tunnel under
  the city.

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More Facts About the Tunnel

• This project is the single most expensive high
  project ever done in America.
• The project was estimated to cost 2.5 billion
  dollars in 1985 but to the day the U.S. has spent
  over 14.6 billion dollars on the project.
• Along with the tunnel the project also included
  the Ted Williams Tunnel, the Zakim Bunker Hill
  Bridge, and the Rose Kennedy Greenway.

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The Start of the Big Dig

• The idea for the Big Dig was first thought of in
  the 1970s though planning for it did not start
  until 1982.
• It was not until 1987 that the bill was passed by
  the U.S. congress to give sufficient funds for
  the project.
• The tunnel was proposed because of the
  constantly congested streets in Boston.
• The tunnel was proposed to replace the six lane
  central artery that runs through there.

6
The Central Artery

• The is what the dig
• looked like during its
• construction heading
• South bound.

7
Planning

• 1983- Environmental impact studies began,
  approved in 1985
• 1987- U.S. Congress passes bill for Federal
  Funding allocating 755M for the project.
  President Regan initially vetoed the project but
  was overrode by Congress.
• 1991- Ground was first broken for Big Dig

8
Breaking Ground

• In addition to political and financial
  difficulties, the project faced several
  environmental and engineering obstacles.
• Constructions area was largely landfill, and
  included existing subway lines as well as many
  pipes and utility lines that would have to be
  replaced or moved.
• Many unexpected geological and archaeological
  obstacles were found, ranging from glacial
  remains to foundations of buried houses and a
  number of sunken ships lying within the
  construction area.
• More concerns included release of toxins by the
  excavation and the possibility of disrupting the
  homes of millions of rats, causing them to roam
  the streets of Boston in search of new housing.

9
Construction Stages

• Engineers had to use high-tech and expensive
  construction techniques in order to allow traffic
  to flow with out restriction.
• In order to support the existing freeway above
  the city streets, engineers built 120 ft.-deep
  concrete walls upon which the highway could rest.
• The Charles River crossing was one of the most
  controversial aspects of the project, as it was
  difficult to find a cost effective way to cross
  the River. The Zakim bridge was the final
  decision, which is the worlds widest cable
  stayed bridge.

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Finishing Touches

• Two major companies, dozens of sub-projects, and
  over 5,000 workers worked to finish the project.
• Boston Began opening various section of the
  underground highway as early as January of 2003
  and was fully open January 13th 2006.
• In 2004 the elevated Central Artery (I-93) was
  dismantled.

12
Big Dig Problems

• The project was estimated at 2.5 billion in
  1985, but total expenses eventually surpassed 15
  billion.
• On July 11, 2006, the I-90 connector tunnel was
  closed indefinitely as twelve tons of ceiling
  concrete in the tunnel collapsed on a car killing
  a woman and injuring others.
• After doing several experiments, engineers
  determined that substandard materials were used,
  that may have caused several leaks in the ceiling
  as well as the collapse.

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Romney Takes Action

• Romney hired an Illinois consulting firm to do a
  stem to stern inspection of the site
• Ordered July 14th (4 days after incident)
• Roads were found to be, fundamentally safe
• Many Problems found throughout the site

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Problems

• Bend in a bracket holding a cable that supports 1
  million pounds of pressure
• Bolt-Epoxy system failed
• Concrete cracks in the support
• Fire Alarm and Detection System need improvement
• Ventilation System

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Green- Viaduct Orange-
Transition Yellow- At Grade Blue-
Tunnel
http//www.massturnpike.com/img/big_dig/multimedia
/maps/completion_lg.jpg
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Ted Williams Tunnel

• Ramp from South Boston to Ted Williams Tunnel
  opened in August (Eastbound Lanes).
• Ramp D opened last Wednesday Nov 22nd
• Ramp D connects the Ted Williams Tunnel westbound
  to Interstate 93
• The reopened ramp represents only about 10
  percent of the total area of the Big Dig tunnels
  and ramps that have been shut down. Other
  sections could take months to inspect and reopen,
  Romney said.

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Bibliography

• http//www.masspike.com/bigdig/index.html
• http//en.wikipedia.org/wiki/Big_Dig
• http//www.boston.com/news/specials/big_dig_ceilin
  g_collapse/
• http//www.thebostonchannel.com/news/10382277/deta
  il.html