A rail line carrying 2-3 heavy freight trains per day passes through MIT’s Brain and Cognitive Sciences Center. The Institute was initially concerned about vibrations from the trains that may effect sensitive equipment planned for the Center, including 2-photon microscopes, electrophysiology rigs, and MRIs.

Acentech measured the vibrations from freight trains and performed transfer mobility tests to determine ground vibration propagation at the site. We measured the vibrations from 36 freight trains over two weeks. We recorded vibrations from six sensors (3 surface sensors and 3 subsurface sensors at the bottom of boreholes up to 115 feet deep). The recorded data was later post-processed to obtain the vibration time waveform as well as vibration spectra (frequency distributions) from each train passage. Acentech’s seismic hammer imparted a known force pulse to the ground near the train tracks. We recorded the vibration response from the hammer pulse at the six sensor locations. We used transfer functions between the sensors and the applied force to calibrate a numerical model of the ground which in turn was used to evaluate the vibration isolation potential of various foundation schemes and building constructions.

Acentech used the rail-induced vibration data to determine the required vibration isolation to protect the sensitive equipment in the building and to assess the effects of rail vibration on the building’s occupants.