IS TRANSFORMING

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         PUBLISHED BY THE AMERICAN COUNCIL OF ENGINEERING COMPANIES             J U LY/AU G U ST 20 07




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Extreme
Engineering: Does
Your Firm Have
What It Takes?
Liability Insurance
Rates Remain
Stable; Outlook
Uncertain
                                                                How the

                                            BIG DIG
EEA Call for Entries
ACEC Urges
More Funding
For FAA
Reauthorization
ACEC Takes Lead on
3 Percent Repeal                            IS TRANSFORMING
                                             BOSTON
      Reprinted with permission of the American Council of Engineering Companies (ACEC),
                              www.acec.org, in cooperation with the
    American Council of Engineering Companies of Massachusetts (ACEC/MA), www.acecma.org.
Boston
How the Big Dig Is Transforming
                                                                                                                                                                                                                                                                                                            Big Dig
                                                                                                                                                                                                                                                                                                            Engineering
                                                                                                                                                                                                                                                                                                            Firsts
                                                                                                                                                                                                                                                                                                            n The world’s widest
                                                                                                                                                                                                                                                                                                            cable-stayed bridge, the
                                                                                                                                                                                                                                                                                                            Leonard P. Zakim Bunker
                                                                                                                           The leonard P. Zakim Bunker Hill Bridge is the
                                                                                                                                                                                                                                                                                                            Hill Bridge, carries 10
                                                                                                                           centerpiece of the Big dig.                                                                                                                                                      lanes of traffic and can
                                                                                                                                                                                                                                                                                                            withstand 400 mph
                                                                                                                                                                                                                                                                                                            winds.



                                                                                                                                                                                                                                                                                                            n The deepest
                                                                                                                                                                                                                                                                                                            underwater tunnel in
                                                                                                                                                                                                                                                                                                            North America. The Ted
                                                                                                                                                                                                                                                                                                            Williams Tunnel in East
                                                                                                                                                                                                                                                                                                            Boston reaches nearly
                                                                                                                                                                                                                                                                                                            100 feet below the
                                                                                                                                                                                                                                                                                                            surface of Boston Harbor.



                                                                                                                                                                                                                                                                                                            n An innovative ground-
                                                                                                                                                                                                                                                                                                            freezing technique
                                                                                                                                                                                                                                                                                                            stabilized Boston’s weak
                                                                                                                                                                                                                                                                                                            soil during construction.
                                                                                                                                                                                                                                                                                                            Approximately 2,000
                                                                                                                                                                                                                                                                                                            pipes eight feet apart,
                                                                                                                                                                                                                                                                                                            were filled with a

Fifteen-year project is considered                                                                                                                                                                                                                                                                          saltwater coolant solution




                                                                                                                                                                                                                                                                          DARREN MCCOLLESTER/GETTy IMAGES
                                                                                                                                                                                                                                                                                                            chilled to minus 30


one of the most innovative                                                                                       by Samuel Greengard                                                                                                                                                                        degrees Fahrenheit.




engineering feats in U.S. history                                                                                                                                                                              After
                                                                                                                                                                                                                                                                                                            n The most extensive




W
                                                                                                                                                                                                                                                                                                            geotechnical
                                                                                                                                                                                                                                                                                                            investigation, testing
                  hen the Central Artery that knifed        Something had to be done. The main artery and        megaprojects—the price tag swelled from $2.6 bil-                                             Before                                                                                       and monitoring program
                                                         its secondary tributaries were hemorrhaging, bleed-     lion to more than $14.6 billion—it has succeeded
                  through the center of downtown         ing the life out of the city’s heart—economically and   in easing Boston’s famous traffic tie-ups.
                                                                                                                                                                                                                                                                                                            in North America
                                                                                                                                                                                                                                                                                                            prepared the way for
                  Boston opened in 1959, the             from a quality-of-life perspective.                        According to the Massachusetts Turnpike Author-                                                                                                                                         excavation, tunneling and
                                                            But all that began to change in 1991 when con-       ity (MTA), the project has trimmed the average trip                                                                                                                                        construction.
                  highway could adequately handle        struction crews broke ground on the Central Artery/     through the center of Boston from 19.5 minutes
                  some 75,000 cars per day. Through      Tunnel Project, commonly known as the Big Dig.          to 2.8 minutes, reduced rush-hour backups from




                                                                                                                                                                            Massachusetts turnpike authority
                                                         The surgery was an overwhelming success. Today          10 hours per day to a couple of hours per day and                                                                                                                                          n One of the largest
the years, the number skyrocketed to upwards of          Boston’s traffic flows smoothly, neighborhoods are      added 300 acres of new parks and plazas. “The proj-                                                                                                                                        tunnel ventilation
200,000 daily vehicles, creating one of the most         once again connected and the economic impact of         ect has made Boston a more viable city with a great                                                                                                                                        systems in the world
                                                                                                                                                                                                                                                                                                            used 151 infrared sensors
congested highways in the country. n Traffic snarled     the project has pumped new life into the heart of       future,” states Richard Dimino, president and CEO
                                                                                                                                                                                                                                                                                                            controlling 140 fans used
                                                         downtown.                                               of A Better City, an organization that promotes
for 10 hours per day and the accident rate surged to        The scope of the project is nothing less than        business interests in Boston.
                                                                                                                                                                                                                                                                                                            to blow fresh air in and
                                                                                                                                                                                                                                                                                                            exhaust fumes out.
four times the national average for urban interstates.   breathtaking. The Big Dig is larger in size than the
                                                                                                                                                                                                               1989: The elevated Central Artery in downtown Boston
                                                         Panama Canal; engineers had to support existing         Clearing Congestion
Similar problems beset the two tunnels under Boston      high-rise buildings, subways and other infrastruc-      The Big Dig is a story of vision, innovation and
                                                                                                                                                                                                               experienced nine hours of gridlock a day.
                                                                                                                                                                                                                                                                                                            n The largest use of
Harbor. Moreover, the Central Artery displaced           ture while constructing tunnels and managing traf-      persistence. The genesis of the project dates to                                              gasoline, road repairs and related costs. “It was clear                                      slurry wall modules in

20,000 residents when it was built, cutting off          fic flow for more than 200,000 motorists a day.         the early 1980s. At the time, Boston faced near-                                              that something had to be done,” Dimino recalls.                                              North America allowed
                                                            Along the way, project engineers faced formidable    gridlock traffic and a realization that the problem                                              Unfortunately, Boston lacked space to widen its                                           crews to conduct
Boston’s North End and waterfront neighborhoods          challenges. For example, Boston’s weak soil couldn’t    was only going to get worse. A mile-long stretch                                              central highways or build new expressways through                                            excavation work within a
                                                                                                                                                                                                                                                                                                            confined space without
from downtown. n Worse, projections forecast that by     support a tunnel, and engineers had to use construc-    of raised highway included 27 on-ramps and off-                                               the city. Compounding matters, most of the
                                                                                                                                                                                                                                                                                                            disrupting transportation
                                                         tion methods that had never before been attempted.      ramps, which contributed to serious slowdowns                                                 city’s residents already considered the old Central
2010, stop-and-go traffic jams would stretch up to 16    Although the Big Dig suffered many of the cost          and dangerous driving conditions and would even-                                              Artery—a.k.a. the Green Monster—an eyesore and                                               systems directly above.

hours a day.                                             and political problems associated with modern-day       tually lead to $500 million a year in additional                                              ongoing problem. Its construction cut off Boston’s


12   ENGINEERING INC.   July / AuGust 2007                                                                                                                                                                                                                      July / AuGust 2007                                ENGINEERING INC.   13
                                                                                                                                                                                                                                        t
                                    Twelve steel binocular immersed tubes, each the
The Timeline                                                                                                                                                                                                                               he project has made Boston                            1998: Peak construction
                                    size of a football field, make up the Ted Williams                                                                                                                                                                                                           years begin. Construction
                                    Tunnel that crosses Boston Harbor.                                                                                                                                                                     a more viable city with a                             begins on the Charles
1982: Work begins on Final
                                                                                                                                                                                                                                                                                                 River Crossing.
Environmental Impact State-                                                                                                                                                                                                             great future.”
ment/Report (FEIS/R).                                                                                                                                                             of the most difficult conditions highway engineers
                                                                                                                                                                                                                                        richard diMino                                           1999: Overall construction
                                                                                                                                                                                  could ever face,” explains Michael Bertoulin, vice                                                             50 percent complete. New
1985: FEIS/R filed and                                                                                                                                                                                                                  a Better city
                                                                                                                                                                                  president of Parsons Brinckerhoff, part of the                                                                 Broadway Bridge opens.
approved in early 1986.
                                                                                                                                                                                  construction management team on the Big Dig.                                                                   Leverett Circle Connector
                                                                                                                                                                                                                                                                                                 Bridge opens.
1986: Bechtel/Parsons                                                                                                                                                             “The challenges associated with keeping the city
Brinckerhoff begins work as
                                                                                                                                                                                  running during the height of construction were                                                                 2000: Nearly 5,000
management consultant.
                                                                                                                                                                                  enormous.”                                                                                                     workers employed on the




                                                                                                                                              Massachusetts turnpike authority
                                                                                                                                                                                                                                                                                                 Big Dig.
1987: Congress approves
funding and scope of proj-
                                                                                                                                                                                  Deep Thinking                                                                                                  2001: Overall construction
ect. Building acquisition and
                                                                                                                                                                                  The first phase of the project involved tunneling                                                              70 percent complete.
business relocation process
begins; no private homes                                                                                                                                                          under Boston Harbor using the immersed tube                                                                    2002: Leonard P. Zakim
are taken.
                                                                                                                                                                                  tunnel (ITT) method. In 1991, a dredger known                                                                  Bunker Hill Bridge
                                                                                                                                                                                  as the “Super Scoop” began dredging 900,000                                                                    completed.
1988: Final design process
under way. Exploratory                                                                                                                                                            cubic yards of earth. This enabled work crews                                                                  2003: I-90 Connector
archaeology begins.
                                                                                                                                                                                  to begin laying steel ITT sections across the har-    the 33-ton sections in 1995. By December of that         from South Boston to
                                                                                                                                                                                  bor. Each of the ITTs consisted of a 15,000-ton       year, the newly christened Ted Williams Tunnel           Rt. 1A in East Boston
1989: Preliminary/final
                                                                                                                                                                                                                                                                                                 opens in January. I-93
design and environmental                                                                                                                                                          composite structure composed primarily of con-        opened on budget and on schedule.                        Northbound opens in
review continue.
                                                                                                                                                                                  crete and a pair of 40-foot steel tubes joined side      But the Big Dig had only just begun. In order to      March. I-93 Southbound
                                                                                                                                                                                  by side and extending 330 feet. By 1992, the          connect the tunnel to I-90, engineers had to build       opens in December.
1990: Congress allocates
$755 million to project.                                                                                                                                                          12 tunnel sections—built by Maryland-based            another tunnel under Boston’s 400-foot-wide Fort         2004: Dismantling of the
                                                                                                                                                                                  Bethlehem Shipbuilding—began arriving at the          Point Channel. The eight-lane highway would              elevated Central Artery
1991: Federal Highway
                                                                                                                                                                                  site. Crews then added concrete to transform the      have to cross over a subway line, run adjacent to a      (I-93). Opening of the
Administration issues
                                                                                                                                                                                                                                                                                                 tunnel from Storrow
Record of Decision, the                                                                                                                                                           steel hulks into structures that would serve as the   manufacturing plant and large post office and run        Drive to Leverett Circle
construction go-ahead. Final
                                                                                                                                                                                  highway’s foundation.                                 beneath commuter rail lines. To extend I-90 under        Connector, which provides




                                                                                                                                                DARREN McCOLLESTER/GETTy IMAGES
FEIS/R approved. Construc-
                                                                                                                                                                                     In 1993, a catamaran barge began towing the        the tracks and across the channel, engineers were        access to I-93 North and
tion contracts begin to be
                                                                                                                                                                                                                                                                                                 Tobin Bridge.
advertised and awarded.                                                                                                                                                           tunnel sections into position. Each of the tubes      forced to push the limits of existing technologies.
Construction begins on Ted
                                                                                                                                                                                  had to be lowered within a fraction of an inch        The process involved a combination of imaginative        2005: Full opening of
Williams Tunnel and South
                                     Cars and trucks travel north through the new                                                                                                 from their designated location in order to ensure     concrete box ITTs, massive ground modification           I-93 South. The opening of
Boston Haul Road.
                                                                                                                                                                                                                                                                                                 the completely renovated
                                     I-93 tunnel.                                                                                                                                 a watertight seal. Workers used global positioning    and “jacked” highway tunnel boxes underneath an          Dewey Square Tunnel,
1992: More than $1 billion
                                                                                                                                                                                  devices and lasers to position pieces of the tun-     operating rail corridor.                                 including new exit and
in design and construction
                                   North End and waterfront neighborhoods from            methods, along with equal doses of creativity and                                       nel within the murky waters of Boston Harbor.            Engineers turned to soil mixing—a Japanese            entrance ramps. Opening
contracts under way. Dredg-
                                                                                                                                                                                                                                                                                                 of the two cantilevered
ing and blasting for the Ted       downtown, forever changing the look of the city        persistence.                                                                            Working 100 feet below the surface—the Big Dig        technique—to modify the pudding-like soil on             lanes on Leonard P. Zakim
Williams Tunnel continues.
                                   and, many contend, damaging its economy.                 “The Big Dig harnessed some of the best tech-                                         was the deepest tunneling project in the history      the bank of the Fort Point Channel. Using heavy          Bunker Hill Bridge. Opening
Downtown utility relocation
                                      The idea of tunneling under the city and its        nical minds in the industry and confronted some                                         of North America—workers finished connecting          blades and rotors, construction workers drilled          of permanent ramps
to clear path for Central
                                                                                                                                                                                                                                                                                                 and roadways at I-90/I-93
Artery tunnel construction         waterfront grew out of the realization that there                                                                                                                                                    down approximately 130 feet and mixed in cement

                                                                                          R                                                                                       I
                                                                                                                                                                                                                                                                                                 interchange and in
begins. Archaeologists find
                                   wasn’t a more practical way to solve Boston’s trans-        emoving the raised roadway                                                           t is a terrific example of                          to create a material that would support 300 to           other areas.
17th- and 18th-century arti-
facts at a North End dig.          portation problems. Fred Salvucci, then secretary           has reinvented and re-knitted                                                        engineering excellence and                          1,000 pounds per square inch (PSI). After solidify-
                                                                                                                                                                                                                                                                                                 2006: Reached substantial
                                   of transportation for the Commonwealth of Massa-                                                                                                                                                     ing an area and creating a mass gravity wall, exca-
1993: South Boston Haul                                                                   the city. It has helped create an                                                       innovation. It will be a case study                                                                            completion of the Central
                                   chusetts and now a senior lecturer and researcher at                                                                                                                                                 vation commenced adjacent to existing commuter           Artery/Tunnel Project in
Road opens. All 12 sections
of the Ted Williams Tunnel         the Massachusetts Institute of Technology, believed    attractive urban environment…”                                                          for building large public projects.”                  rail lines at the channel edge. The area became the      January. Spectacle Island
                                                                                          Michael Bertoulin                                                                       aBBie r. GoodMan                                                                                               Park opens to the public.
are placed and connected on        it was absurd to “simply rebuild a 50-year-old                                                                                                                                                       interface between the ITTs and jacked tunnels.
harbor floor.                                                                             Parsons Brinckerhoff                                                                    acec/Massachusetts
                                   mistake so that it could hang around for another                                                                                                                                                     However, low bridges in the channel prevented            2007: Restoration of
                                   50 years, polluting and obstructing the economic                                                                                                                                                     crews from building the ITTs off-site. Instead,          Boston city streets.
1994: Charles River Cross-
                                                                                                                                                                                                                                                                                                 Continued construction
ing revised design and             growth of the city.” He also recognized that total                                                                                                                                                   engineers created a 60-foot-deep and 1,000-foot-         of the Rose Kennedy
related FSEIS/R approved.
                                   closure of existing roadways was not an option.                                                                                                                                                      long dry dock, otherwise known as a casting basin.       Greenway and other
New set of loop ramps open
                                      After studying the city’s transportation problems                                                                                                                                                 The basin held six different concrete sections dur-      parks. Construction on
in Charlestown.
                                                                                                                                                                                                                                                                                                 development parcels
                                   in the early 1980s, traffic planners recommended a                                                                                                                                                   ing construction.                                        continue after the
1995: Ted Williams Tunnel
                                   $2.6 billion initiative that would ultimately grow                                                                                                                                                      The challenges didn’t stop there. Crews had to        Central Artery/Tunnel
opens to commercial traffic.
                                   into a comprehensive quilt of 140 construction                                                                                                                                                       float the 27-foot-high sections (which measured          Project is finished.
1996: Downtown slurry              projects. Construction would span more than a                                                                                                                                                        up to 414 feet long and 174 feet wide) into place.
work under way for I-93
                                   decade and redefine modern highway engineering.                                                                                                                                                      Construction teams also couldn’t build all the           SOURCE: Massachusetts Turnpike
tunnels.                                                                                                                                                                                                                                                                                         Authority.
                                   Urban planners and engineers could not have fore-                                                                                                                                                    structures at the same time—meaning the basin
1997: Overall utility work 80      seen what a complicated and challenging project                                                                                                                                                      had to be filled and drained more than once. Two
percent complete.
                                   the Big Dig, approved in 1987, would become.                                                                                                                                                         of the sections served as the foundation for venti-
                                   It would require new and untested engineering                                                                                                                                                        lation structures on their roof—thus making the


14   ENGINEERING INC.   July / AuGust 2007                                                                                                                                                                                                                                          July / AuGust 2007   ENGINEERING INC.   15
                                                                                                                                                      KEy PLAyERS
                                                                                                                                                       FREd SAlvuCCI
By the                                                                                                                                                 An engineer and former
Numbers                                                                                                                                                Massachusetts transportation
                                                                                                                                                       secretary (1983–1990), he is
n Amount of dirt                                                     process of transporting them, and balancing their
excavated: 15 million                                                                                                                                  credited with first envisioning
cubic tons.
                                                                     weight within the water, even more complex.                                       the concept of the Big dig
                                                                        Using remote control cameras, engineers posi-                                  and generating the project’s
n Concrete used to replace                                           tioned the pieces and connected them like giant                                   initial financial and political
the dirt: 3.8 million cubic
feet.
                                                                     Lego blocks.                                                                      support.
                                                                        Constructing the last link between the ITT and                                                                                                                                                                                                              Before
n Steel used: 26,000                                                                                                                                   SAlly PERRIN
                                                                     I-90 created another challenge. Engineers had to
linear feet.                                                                                                                                           Former deputy project
                                                                     dig under commuter rail lines carrying more than
                                                                                                                                                       manager for the Bechtel/
n Traffic management                                                 150 trains and 100,000 passengers a day, without




                                                                                                                                                                                            Massachusetts turnpike authority
                                                                                                                                                       Parsons Brinckerhoff team,
system: 400 video cameras,                                           disrupting the tracks. Once again, workers faced the
130 electronic message                                                                                                                                 she oversaw environmental
signs, 30 infrared height
                                                                     problem of soft soil that couldn’t support tunneling.                             mitigation, real estate and
detectors, six emergency                                             Any attempt to remove the soft soil under the tracks                              traffic management as they
response systems.                                                    risked derailing the entire project. That’s when one                              prepared for construction.
n Reduction in air pollution
                                                                     contractor proposed a new and radical solution:
due to central artery                                                Freeze the soil during the tunneling process using                                                                                                                                                                                                                                                 After
project: 12 percent citywide.                                        2,000 pipes located eight feet apart, each filled with a                          JOHN KENNEdy
                                                                     brine refrigerant solution chilled to minus 30 degrees                            Senior principal at vanasse                                             Once a mass of elevated highway ramps, North           On Jan. 18, 2003, officials raised the      for five months while workers replaced the
n Maximum number of                                                                                                                                                                                                            End Park, part of Boston’s Rose Fitzgerald
                                                                     Fahrenheit. “It was like creating a manmade per-                                  Hangen Brustlin, Inc.,                                                                                                      sign on I-90 and opened the last section       panel’s anchor. Later, Thomas F. Reilly,
construction workers
on project: approximately                                                                                                                              he designed the traffic                                                 Kennedy Greenway, will open in spring 2008 (top
                                                                     mafrost,” Bertoulin says. Workers mined 18 inches                                                                                                                                                             of the 3,462-mile link to Seattle. A year      attorney general for Massachusetts, filed
5,000.                                                                                                                                                 management plan that                                                    right). A series of 14 parks will cut through the
                                                                     into the frozen soil, creating a void using the tunnel-                                                                                                                                                       later, workers dismantled the old I-93         15 lawsuits against firms that he accused
                                                                                                                                                       maintained safe and efficient                                           city from Causeway to Kneeland Streets (above).
n Number of construction                                             jacking process. The tunnel jacking required 10,000                                                                                                                                                           structure and began replacing it with 300      of negligence in the ceiling collapse.
contracts executed: 109.
                                                                                                                                                       traffic operations during the
                                                                     PSI to move the 35,000-ton sections at a rate of                                                                                                                                                              acres of parks and plazas. “Removing the          Nevertheless, the Big Dig left a
                                                                                                                                                       15-year Big dig construction
n Underground utilities
                                                                     three feet per day until they were in place. The pro-                                                                                                     supporting the bridge and two cantile-              raised roadway has reinvented and re-          remarkable imprint on Boston. With 7.8
                                                                                                                                                       period.
relocated: 29 miles of                                               cess took three years to complete, but left the struc-                                                                                                    vered on the east side. It is designed to           knitted the city,” Bertoulin says. “It has     miles of highway and 161 total lanes,
gas, electric, water, sewer,                                         tures on the surface untouched.                                                   PAul HARRINGTON                                                         withstand 400 mph winds and a magni-                helped create an attractive urban envi-        it has greatly reduced traffic, accidents
telephone and other lines                                                                                                                              director of structural division at
managed and maintained by
                                                                        In September 2001, a massive leak occurred in                                                                                                          tude 7.9 earthquake.                                ronment that otherwise wouldn’t have           and air pollution. A new park—the
31 companies.                                                        the section where the land and sea tunnels met.                                   Fay Spofford & Thorndike, Inc.,                                            Throughout the Big Dig, engineers had            been possible.”                                Rose Kennedy Greenway—will accom-
                                                                     Rapidly rising water inundated expensive cranes                                   he developed the underpinning                                           to keep cars flowing. “It was essential to                                                         modate joggers, picnickers, workers on
n Deepest point: 120 feet                                                                                                                              (foundation support) system
at Dewey Square, where it
                                                                     and other equipment and made the tunnel impass-                                                                                                           understand how every aspect of the project          Leaving a Legacy                               lunch breaks, local residents walking
                                                                     able. Although crews began working on the prob-                                   that allowed tunnel construction                                        would affect traffic patterns and driving           Though the Big Dig has distinguished           dogs, and children at play. And the Bos-
passes beneath the
Red Line subway.                                                     lem immediately, it took divers nearly eight weeks                                to proceed without affecting                                            conditions,” explains John J. Kennedy, a            itself as an engineering marvel on par with    ton waterfront, now reconnected to the
                                                                                                                                                       existing transit/rail systems or
n New parkland: 300 acres
                                                                     to identify and plug the leak. By then, the opening                                                                                                       traffic consultant with Watertown, Mass.-           the Panama Canal, Europe’s Chunnel and         city, is enjoying an economic boom.
                                                                                                                                                       surface structures.
(27 acres reclaimed from                                             of the tunnel was delayed by four months.                                                                                                                 based Vanasse Hangen Brustlin, Inc. “We             the Hoover Dam, its accomplishments are           “It is a terrific example of engineering
the elevated highway).                                                                                                                                 SENA KuMARASENA                                                         had to make sure that total coordination            not without controversy. At $14.6 billion,     excellence and innovation. It will be a
n Toxic contaminants
                                                                     Driving Results                                                                   HNTB associate vice                                                     existed among various contractors and               the Big Dig is the most expensive highway      case study for building large public proj-
hauled away: 435,000 cubic                                           The final piece of the project was the engineer-                                  president, he served as                                                 government agencies.” Engineers rerouted            project in history and its eventual price      ects,” says Abbie R. Goodman, executive
yards of soil and other debris.                                      ing of the tunnel beneath I-93. To clear space for                                project engineer and project                                            traffic daily and, almost without excep-            tag—more than $12 billion above the ini-       director of ACEC/Massachusetts.
                                                                     the underground highway, engineers had to build                                   manager during the design                                               tion, improved traffic flow during the con-         tial estimate—has left some citizens and          The legacy extends far beyond Bos-
The old elevated High Bridge                                         corridors to relocate pipes, cables and other infra-                              and construction of the                                                 struction phase, he recalls.                        government officials angry and dissatis-       ton. “Many of the design and engineer-
over the Charles River is                                            structure that fills virtually every square inch of                               leonard P. Zakim Bunker Hill                                               At its peak, the Big Dig employed                fied. The Massachusetts Turnpike Author-       ing methods used for the Big Dig have
demolished in early 2004.                                            subterranean Boston. At one point, they had to dig                                Bridge, the widest cable-                                               nearly 5,000 construction workers. The              ity filed a $146 million breach-of-contract    been picked up and applied to other
                                  Massachusetts turnpike authority




                                                                     underneath three levels of subterranean transporta-                               stayed bridge in the world.                                             management team of Bechtel Corp. and                lawsuit in 2004 over cost increases and        projects around the world,” Bertoulin
                                                                     tion systems—subway lines, heavy rail and a bus                                                                                                           Parsons Brinckerhoff oversaw 38 design              other lingering issues, including outstand-    explains. And although some techniques
                                                                     station—and create a tunnel space only 36 inches           been attempted on such a large scale.                                                          contracts and 119 construction contracts            ing legal and insurance claims, with the       are so specialized that they haven’t
                                                                     beneath the subway.                                           Project planners also recognized the need to                                                involving 109 companies. “It was a very             Commonwealth of Massachusetts. ACEC/           yet made their way into mainstream
                                                                        “Essentially, we had to create a parallel set of        replace a deteriorating three-lane double-decker                                               schedule-driven project that required tre-          Massachusetts is now sorting through the       engineering projects, the innovation
                                                                     walls with huge crossbeams beneath the exist-              bridge over the Charles River used to connect                                                  mendous synchronization of people and               mess. “It’s a complex matter that will take    and lessons learned have proved invalu-
                                                                     ing raised structure in order to build the tunnel.         the tunnel to the interstate. Further complicating                                             resources,” explains William J. Rizzo,              years to resolve,” Leathers says.              able. “That’s the nature of engineer-
                                                                     The ground had to support both the existing                the project, engineers decided it was necessary to                                             former CEO and president of Tetra Tech                 The project also endured its share of       ing and construction,” Bertoulin says.
                                                                     steel and concrete structure and the tunnel box,”          build around the existing bridge structure so that                                             Rizzo, which handled the engineering                tragedies. Sadly, four workers died while      “Every project draws on the knowledge
                                                                     says Frank Leathers, a geotechnical engineer               traffic continued to flow during construction.                                                 for two interchanges along I-93. “We                building the tunnels and infrastructure.       gained from previous projects, and every-
                                                                     and president of GEI Consultants, Inc., which              Today, the $100 million cable-stayed Leonard                                                   had people from different companies—                In July 2006, a motorist passing through       one benefits.” n
                                                                     designed one section of the slurry walls for the           P. Zakim Bunker Hill Bridge, the widest asym-                                                  with entirely different cultures—working            the I-90 connector tunnel was killed after
                                                                     project. Prior to the Big Dig, Leathers says, the          metrical bridge ever built, carries 10 lanes of                                                together [in a joint venture] to achieve a          bolts failed and a 12-ton concrete slab fell   Samuel Greengard is a business and technol-
                                                                     slurry wall module building method had never               traffic—eight through the legs of twin towers                                                  mutual goal.”                                       atop her vehicle. The tunnel was closed        ogy writer based in West Linn, Ore.


16   ENGINEERING INC.   July / AuGust 2007                                                                                                                                                                                                                                                                                               July / AuGust 2007   ENGINEERING INC.   17

				
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