Train Ground-Borne Vibration Control Measures and Validation Tests to Meet Stringent Vibration Thresholds for University of Washington Research Labs

Seattle Sound Transit’s Link Light Rail extension to Northgate runs under the University of Washington (UW) campus that is home to world-class research facilities with vibration-sensitive equipment. Sound Transit has installed 1150 m of 5 Hz floating slab track in each of the twin bore tunnels. The train vibration is required to meet stringent vibration limits for 24 buildings over the 2–100-Hz third octave bands. Prior to opening of the new extension for revenue service, detailed compliance verification tests were performed for worst-case operating scenarios. Based on these tests, the vibration limits were amended at four sensitive buildings for the 5-Hz third octave band frequency. This paper presents the results of the compliance tests, performance of the floating slabs, and the determination of allowed train speeds under the UW campus.