What do you do when you're faced with the task of expanding a building on a site that doesn't allow for horizontal expansion or relocation? In the case of the Tufts Dental School in the Tufts University Medical Center in Boston's Chinatown, the answer was simple: expand vertically. Though this seems like an intuitive and obvious answer, the practicality of constructing the five-story addition in this congested urban space presented a number of logistical problems specific to this site-from concerns about building on top of an MBTA tunnel (Boston's subway) to having to communicate with the Chinese community by having safety and warning signs in both English and Chinese. But through early preparation and constant communication with the client, subcontractors, and architect, among others, Shawmut Design and Construction was able to navigate these unique issues without too much difficulty.
Aside from the initial siting and engineering of the addition, the most prominent challenge Shawmut faced when constructing this addition was the lack of perimeter space for placement of the tower crane. Given the congested environment and the limitations that the MBTA tunnel presented, there was a significant amount of planning and engineering that went into the placement of this crane. “The existing building is adjacent to the MBTA line, which is the subway in Massachusetts. So our laydown area is approximately 150 x 50 for the whole building and that includes our loading dock,” says Tony Miliote, Shawmut Design and Construction's managing director of healthcare and science. “On the other side of the building is the theater district so there's nowhere to move. On another side, there's a very small alley, and on the other side there's another small alley. The one area where the MBTA tunnel was, we could not put the tower crane to erect the building because we would've crushed the tunnel. The other two locations where the alleys are: One alley wasn't large enough for us to put a mobile crane in to erect the tower crane or we would've slammed the mobile crane into the building. In the other alley, there's a sky bridge connecting the hospital to our dental school, so we would not have been able to move our mobile to pick up the tower crane.
“So what we had to do was hire an independent engineer. We built a large structural base frame and bolted the tower crane to the roof of the 10-story building and put it in the middle of our addition, which I've never seen before in my career.”
But even erecting the tower crane on top of the building presented its own set of problems. On top of the existing building were 7,000 tons of cooling towers which, because of the addition, had to be moved elsewhere. Shawmut decided to move the cooling towers during several weeks from January to March, 2008-a time when cooling was least needed in the building-to the adjacent 10-story building. Proper construction of the Tufts Dental School addition was able to start in April of 2008.
All of this engineering came with various other measures that had to be taken, including shutting down roads and bringing in mobile cranes for support. “We had to shut down the roads numerous times because of the mobile crane that had to come out to relocate the cooling towers and reset the air handling equipment-we had to rip the 9th and 10th floors off the existing faéade to get our new air handling units in that's approximately 60 feet long by 20 feet wide by 30 feet high-we had to bring a 350 ton mobile crane in because our tower crane couldn't lift these pieces of equipment,” says Miliote. “On numerous weekends throughout the last 16 months, we've had to close both lanes of traffic on Washington street in the theater district to lift all of the mechanical and electrical equipment, cooling towers, and structural steel for the mechanical equipment.