May 2, 2008
Monitoring vibrations associated with B3C construction

As construction of the new Building for the Third Century (B3C) progresses, some may not only have seen construction activity, but also may have felt some vibrations in buildings adjacent to the construction site. So, one may ask, "How are these vibrations kept at a safe level for patients and staff?"

The MGH Planning and Construction Office, the MGH Safety Office, and the Thrive B3C Operations Committee and its Noise, Vibrations and Particulate (NVP) Subcommittee work together to ensure the utmost safety of patients and staff as well as the uninterrupted work environments of MGH employees, clinicians and health care workers. The Thrive Committee and NVP Subcommittee regularly convene to address any construction-related concerns before they become issues.

Working with McPhail Associates, Inc., a firm specializing in geotechnical and geoenvironmental engineering, a great deal of scientific planning has been conducted to minimize the levels of construction-related vibrations, which are a normal and expected element of any construction project. According to Bob Hoyler of McPhail Associates, vibration is measured in terms of velocity, and the generally accepted threshold of human perception of vibrations is a level of 0.02 inches per second — equivalent to riding in a car at about 0.001 miles per hour. To stay under a reasonable level of vibration that, although above the threshold of human perception, allows construction activities and the hospital environment to co-exist, MGH construction experts and consultants have established a maximum allowable vibration criterion of 0.375 inches per second — the equivalent to riding in a car at about 0.02 miles per hour.

Since demolition began, vibrations — as well as noise and dust levels — have been monitored 24 hours a day, seven days a week. Sophisticated seismographs are located in buildings at six locations around the construction site to measure vibration levels, as each building responds differently to vibrations depending on its structural systems, foundation designs and the types of soil on which it was built. When levels greater than one-half of the allowable limit are detected, members of the project design and construction teams automatically are notified, and construction staff members ascertain the source of the vibration and assess if alternative construction methods can be employed.

Vibrations can be expected throughout construction of the B3C, which is scheduled to be completed in 2011. With the Thrive Committee, NVP Subcommittee and consultants working together, individuals can be assured that all precautions are being taken and safety is paramount. MGH staff and employees are encouraged to report any construction-related concerns at any time to the MGH Buildings and Grounds Call Center at (617) 726-2422. For more information about the B3C, visit

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