Built in 1812, New York’s City Hall ranks among the most important historic buildings in the nation’s most populous and, some would argue, grandest city. With its elaborate furnishings and interiors, invaluable fine arts collection, and gorgeously decorative plaster ceilings, it has been a fitting home to the city’s 108 mayors (including the incumbent, Michael Bloomberg), City Council members, and numerous municipal executive and legislative offices for two centuries. It stands as one of the nation’s oldest city halls still in continuous use.
City Hall last received a major renovation nearly a century ago. Four years ago, a Building Team led by construction manager Hill International took on the monumental task of restoring City Hall for another couple of hundred years of active service.
The job posed some unusual problems. City Hall sits atop four subway lines, which raised concerns about vibration during construction. Both its American Georgian interior and Federal-style exterior have been designated New York City landmarks and are listed on the National Register of Historic Places, making any attempt at restoration a white-glove job. And, as the Building Team would learn, excavation of the site would uncover archeological artifacts whose documentation and preservation had to be completed before work could continue.
PROJECT SUMMARY
CITY HALL
New York, N.Y.Building Team
Submitting firm: Hill International, Inc. (CM)
Owner: New York City Department of Design and Construction
Architect: Beyer Blinder Belle
Structural engineer: Robert Silman Associates
MEP engineer: Lakhani & Jordan
Fire/life safety consultant: Rolf Jensen & Associates
General contractor: Rockmore Contracting Corp. (phase 1); Plaza Construction (phase 2)General Information
Size: 70,000 sf
Construction cost: $93.5 million
Construction time: September 2008 to July 2012
Delivery method: CM at risk
The Building Team also had to contend with the political theatricality of the place—the possibility that at any moment the Mayor might call a press conference that would halt work, or a tour group would come through and interrupt reconstruction activity, or the adjacent park might become the site of a demonstration that could disrupt the delivery of materials. Compounding these logistical issues was a well-publicized fixed date of completion: July 1, 2012, the bicentennial of its original occupancy.
The Hill-led team took on the challenge in bold fashion, starting with the 1903-era ceiling in the 4,050-sf Council Chamber. The 75x54-foot ceiling, with its elaborate oil-on-canvas murals—a central oval panel measuring 40x22 feet surrounded by four 11x11-foot octagonal panels, which are mounted onto the plaster ceiling—towered nearly 29 feet above the floor, complicating the task of restoration.
To enable its team of 11 specialty conservation contractors to execute the work to the level of detail and quality that the project called for, the Building Team erected a temporary “ballroom floor” 11 feet below the ceiling, rather than using scaffolding.
This enabled the conservators to work with much greater precision on the ceiling and allowed them to discover areas of deterioration that might not have been addressed under conventional methods. The canvasses were hand-scraped from the plaster base and removed for off-site refurbishment.
'Trench warefare' in Lower Manhattan
Another massive undertaking involved the revamping of the building’s electrical service. Previously, City Hall obtained its electricity from feeds running from the Tweed Building across the street via an underground tunnel.
To provide City Hall with its own source of electrical service, the Building Team proposed running the electrical feed from a vault located across the street to a newly constructed electrical sub-basement beneath the East Wing. This would require digging an open trench of two thousand linear feet.
Unfortunately, the route of the trench went through a rich lode of archeological artifacts and graves, which meant that work had to be halted with every new discovery. Compounding the problem, the excavation posed a threat to the nearly 300-year-old trees on the park site. The pace of excavation slowed to two feet a day.
Hill International turned for advice to colleagues who were working on local subway projects. They suggested the use of a micro-tunnel boring machine. This device allowed the City Hall team to cut a 32-inch tunnel at a depth of 15 to 20 feet, thereby avoiding any contact with artifacts or human remains. A job that could have taken eight months was completed in three and a half weeks, saving $2-3 million.
Although some work is still proceeding, to date the renovation of City Hall has consumed 2,300,000 man-hours, making it one of the most elaborate reconstruction projects in recent U.S. history.
“This was a very experienced team that executed a spectacular restoration of an important symbol of New York City,” said Reconstruction Awards Honorary Chair Walker C. Johnson, FAIA. “Great attention to detail resulted in an exquisite, newly restored structure.” +
Related Stories
Multifamily Housing | May 1, 2015
Trade groups extend campaign to promote apartment living
The groups claim that there are more than 37 million Americans—12% of the population—living in just under 20 million apartment units nationwide. Apartments and their residents contribute $1.3 trillion annually to the economy.
Contractors | May 1, 2015
Nonresidential fixed investments fall in latest Construction Economic Update
This is the first time that nonresidential fixed investment declined since the first quarter of 2011, ABC reported. Nonresidential fixed investment had been rising by more than 4% on an annualized basis during five of the previous six quarters.
Architects | Apr 30, 2015
Safdie Architects accepting applications for 2015 Research Fellowship
The program, which features a theme of “dense urbanism,” encourages participants to tackle the challenges associated with contemporary urban landscapes using new tools and solutions to create a better functioning and humane city.
Museums | Apr 27, 2015
Finalists’ designs for Guggenheim Helsinki competition released
A custom-developed App engages an international public in the selection process.
Wood | Apr 26, 2015
Building wood towers: How high is up for timber structures?
The recent push for larger and taller wood structures may seem like an architectural fad. But Building Teams around the world are starting to use more large-scale structural wood systems.
Museums | Apr 23, 2015
Moshe Safdie unveils pentagonal scheme for National Medal of Honor Museum
The new museum near Charleston, S.C., will archive the history of the nation's highest military honorees.
Green | Apr 23, 2015
3 sustainable projects take top prize in 2015 Global Holcim Awards
Projects from Colombia, Sri Lanka, and the U.S. were chosen by the Holcim Foundation for the impact the projects have on their local communities.
High-rise Construction | Apr 23, 2015
Size matters in NYC, where several projects vie for the city’s tallest building honor
The latest renderings of 217 West 57th Street show a tower that would rise higher than the World Trade Center’s pinnacle, when elevations are included.
Multifamily Housing | Apr 22, 2015
Condo developers covet churches for conversions
Former churches, many of which are sitting on prime urban real estate, are being converted into libraries, restaurants, and with greater frequency condominiums.
High-rise Construction | Apr 22, 2015
Architects propose sustainable ‘vertical city’ in the Sahara
Designers aim to make the 1,476-foot tower sustainable, relying on rainwater collection, solar power, and geothermal energy.