The Day the Earth Shook: Controlling Construction-Induced Vibrations in Sensitive Occupancies

Abstract

Floor motions can disturb occupants, leading to frequent complaints and loss of functionality. In healthcare facilities, this issue can be more critical, as high-resolution imaging equipment with stringent vibration criteria are often employed. As existing healthcare infrastructure ages, extensive renovations and additions to functioning facilities are commonly being planned, designed and constructed. In many cases, these largely invasive projects are occurring while the existing vibration-sensitive facilities remain in operation. The control of construction-related vibrations form an increasingly important component of the planning, design and construction processes for these situations.

This paper provides two case studies of existing hospitals which are undergoing extensive additions. In both cases, the diagnostic imaging (DI) suites, containing Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) equipment, are located directly adjacent the facility additions. For both cases, a series of vibration tests are described that were conducted using a combination of backhoes, excavators, caisson drillers and vibratory compactors to determine the extent of mitigation and monitoring required during the construction process in order to allow the DI equipment to remain in operation. Further commentary is provided regarding the practical realism of vibration criteria for DI equipment, as it was found for one of the cases discussed below that the manufacturer-provided vibration criteria for a CT scanner were apparently inaccurate since construction activity generated vibrations that exceeded the constraints of those criteria without any subjectively apparent loss of performance.