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.
“So we've had to coordinate closely with the city of Boston as well as the subway. As we brought out the mobile cranes, we had to stand them over the existing subway tunnel. We needed to be sure we wouldn't crush the tunnel. On one occasion, we had to bring in the largest crane in all of New England, which is a 650-ton mobile crane.”
Safety precautions were also an important consideration in the construction of this addition. Aside from the aforementioned communication with the local Chinese community, Shawmut constructed pedestrian tunnels and nets around the perimeter of the building to catch any falling debris, as well as hired an outside engineer to design the base frame for the tower crane, to avoid the possibility of it collapsing-a type of incident that's been happening with higher frequency on similar construction projects in New York.
Even with all of these logistical issues, the Tufts Medical Center remained open and operational throughout the entire process. Shawmut provided temporary power for all of the buildings during the process so that they could remain in operation. “The building was entirely functional for the entire duration of the project. The school, the dentists, the patients, the hospital, have not lost a day,” says Miliote. “We communicated with executives and the associate dean on a daily basis as to what would be transpiring on the project every day. We also had to renovate their lobby. We switched the entrances of the lobby to ensure that they can continue to have access to one side of the lobby as we renovate the other side. They had a bank of four elevators and we restored two at a time to ensure that they had two elevators for use in the 10-story existing building at all times.”
Miraculously, Shawmut ran into very few other unexpected problems throughout the entire process. The tower crane presented the majority of the logistical issues, and the proximity of the adjacent buildings made the installation of the curtainwall difficult, but other than those unexpected trials, the project was a smooth process. Miliote chalks much of this success up to a long-standing relationship with Tufts University, constant conversation between all active parties, and the year spent in preconstruction, planning for difficult situations.
“We met with the university, end user, hospital, architect, structural engineer, mechanical and electrical engineers, and geotechnical engineer,” says Miliote. “In some cases we were meeting with the developers on a weekly basis to continue to look at the drawings, determine the means, budget, scheduling, and staging of the project. We all were challenging the assumptions of the project to make sure that the client got the best value. Over the course of the year of preconstruction, we probably met with all of the different constituents, at different times, upwards of 40 or 50 times.
“It's a very complex project in a very urban setting with nowhere to move at all, but because of the year of planning with the end user and the university, and the constant communication, the project has-we're not finished, we have about three more months left on-site-the project has gone very smoothly. We've had no accidents on-site. The hospital, university, and patients have been able to learn constantly through construction. A lot of diligence, a lot of communication, and a lot of planning went into make the project go off smoothly.” HBI