Design to Demolition

There’s something deep-ly appealing about a construction site. At one time or another, most of us have lingered to watch a crane hoist a heavy beam or stare into a massive excavation pit. But for MIT professor of civil and environmental engineering Sarah Slaughter, construction’s bewitching power has less to do with big equipment than with the chaotic order of complex, collaborative activities. Add to the visible interplay of people and machines the unseen political, economic and artistic forces in play at a building site, and you can start to appreciate Slaughter’s career-consuming fascination with construction.

Slaughter’s specialty is innovation, something this conservative industry is not exactly famous for. She is creating detailed computer models of construction processes to try to understand the impacts of new designs, methods, materials and systems, and how improvements can be disseminated in the industry.
With Boston’s building boom in full swing, the city has become a living laboratory for Slaughter and her students. On a windy afternoon, TR Associate Editor Antonio Regalado and Editorial Intern Nurit Bloom got the chance to see a construction site through Slaughter’s eyes.

Just north of the MIT campus in Cambridge, an office building and a hotel are springing up side by side. Pointing to the partially enclosed steel frames, Slaughter remembers her early interest in construction:

Slaughter: When I was a kid, my dad used to sneak me onto sites like these all the time. I tell him it’s all his fault that I became interested in construction, which most people think is a pretty pedestrian research topic, not at all high-tech.

I double-majored in anthropology and civil engineering at MIT. My graduate work was also at MIT in engineering, management and policy. I learned how engineering can improve society through the civil infrastructure, and I came to see the whole process of construction, from design to demolition, as a point of great influence in society. At the same time, I was working with my husband’s construction company. He’s an MIT grad too, and he kept wanting to try out new materials, which always had all kinds of interesting, unexpected repercussions.

In front of us,workers secure concrete panels onto the beam work. Higher up, welders send down showers of sparks. A level above that, small figures lay decking.

SS: So many things happen in parallel across a construction site that if you change the way one activity is done, it can have a real ripple effect. My students and I build computer models to keep track of that. We wander around on site and time how long it takes each worker to perform every task. We spend a lot of time just figuring out what they are actually doing. In the erection of cast-in-place concrete columns, we modeled approximately 250 different tasks from placing reinforcing steel bars to building formwork, about 150 of which can happen simultaneously. We try and accurately represent the entire process so that we can anticipate and understand the changes an innovation brings. The contractors love these models, because they are done from a point of view that makes sense to the people on the site.

Workers are hoisting precast concrete panels tiled with ornamental brick work.

SS: Preassembled facades is an area very rich with innovations right now. By installing the bricks at a factory, you can reduce the amount of time your workers have to spend up in the air, exposed to dangerous conditions. That can have enormous societal benefits by decreasing the number of injuries and deaths. But right now, the main driver for this kind of innovation is speed. The sooner a developer can get these buildings on the market, the sooner they can sign a 10-year lease with a tenant and reduce their financial risk.

It’s a complex picture, because to put an innovation to work you need an agreement by a lot of people on the site. In this case, the bricklayers’ union doesn’t like these preset panels because they could lose their jobs. On top of economics, there are aesthetic factors. It’s the City of Cambridge that requires brick facades in the first place.

On top of one building, barely visible from the ground, sits a small tree.

SS: The last piece of steel is called the top piece; the workers put a fir tree and a flag on top. Some say the fir tree is to appease the gods from whom you are taking the materials to build this building. Others say that it’s to show that you’ve created a new element in the environment.