Sean Collier Memorial

A spontaneous, temporary improvised memorial of flowers, messages, and small objects appeared shortly after news of Collier's death.[1] The MIT community wanted to create a permanent memorial, and assembled a committee of students, faculty, and police officers. A public call for ideas was put out in June 2013.[1] The final design for the memorial was unveiled in April 2014, allowing only a year for fabrication of components and construction.

J. Meejin Yoon, then head of the MIT Department of Architecture, led the team which conceived the overall shape and design.[2] Essential structural engineering design was done by MacArthur Prize professor John Ochsendorf and his students.[3][1] The construction was performed on a tight schedule by Boston-based Suffolk Construction, coordinated by their project manager Rob Rogers, who was also a stepbrother of the slain officer.[1][4]

On April 29, 2015, MIT held special ceremonies dedicating the memorial.[5] MIT President Rafael Reif observed that the memorial represented the community coming together after tragedy: "We are held together by invisible forces too".[1]

The memorial consists of 32 massive granite blocks precision-shaped under computer numerical control, and fitted together into a shallow open domed arch with 5 radial support wings splayed out like fingers of an open hand.[2][4][1] This shape is a reference to the MIT motto Mens et Manus (Mind and Hand),[2] and to Collier's spirit of helpfulness.[1] The granite material is a reference to Sean Collier's love of hiking through the nearby White Mountains (New Hampshire) with the MIT Outing Club (MITOC).[6]

The architect, J. Meejin Yoon, has written that the heavy stone blocks mutually support each other, expressing strength through unity. They shelter a large ovoid cavity that represents "a passage, a marker, and an aperture that reframes the site".[3][2] The void represents the absence of the slain officer,[1] and is shaped like an oblong stone from a memorial cairn which had been constructed at trailside by Collier's friends from MITOC.[6]

The design was carefully evaluated by John Ochsendorf and his students using computer simulation to study its resistance to a major earthquake. Compressive forces on each block were calculated to be in the range of 20,000 to 50,000 pounds (9,100 to 22,700 kg).[4][1] Each joint between the stone blocks was shaped to be perpendicular to the forces transmitted through the joint, visually expressing the invisible forces that hold the structure up.[4][1] The underground foundation, an essential part of the structure, is made of reinforced concrete to resist the spreading forces produced by the shallow arch it supports. The 190-short-ton (170,000 kg) weight of the structure is supported by mini-piles driven to a depth of 30–40 feet (9.1–12.2 m).[1]

The polished, tapered stone blocks, carved to a precision of 0.5 millimetres (0.020 in), were installed by a specialized team of riggers operating a crane and machinery, under the guidance of Ochsendorf, his team of students, and a construction manager. The temporary support scaffolding was slowly lowered over the span of 8 hours, while the descent of the central 12,000-pound (5,400 kg) keystone was carefully monitored. Predicted to settle 5 to 15 millimetres (0.20 to 0.59 in), the stone was actually measured as descending 6 millimetres (0.24 in).[1]

The memorial is physically sited immediately next to the location where Sean Collier was murdered. An opening in the structure frames a view of the spot where he was sitting in his MIT Police car responding to a call for help, when he was ambushed and shot.[7][6][1] Raised stainless steel buttons encoding Collier's police badge number "179" in Braille are installed into the pavement beneath the memorial arches, to discourage its abuse by skateboarders.[1] Smaller granite blocks are placed around the periphery of the memorial, to provide seating for visitors.[1]

At night, in-ground LEDs illuminate the structure, and also represent the configuration of the stars overhead on the fatal night of April 18, 2013.[3][1]

• Humphries, Courtney (May 22, 2015). "The Making of MIT's Collier Memorial". Architect: the journal of the American Institute of Architects. Hanley Wood Media. Retrieved 2015-07-08. Detailed article includes several architectural drawings showing siting, structural components, and foundations of the memorial.