Urban Blasting Vibrations: Case Histories of Vibration Monitoring in New York City

This paper summarizes the monitoring experienced gained from several urban rock blasting projects in New York City and one just beyond the city limits. The majority of the experience was gained on the new South Ferry Terminal Structural Box project that included a new subway terminal station and section of tunnel on the number 1-line subway located in Battery Park in Lower Manhattan. The paper will review lessons learned and the limitations of using “off-the-shelf” seismographs for near-field blast monitoring. We allege that standard and widely available seismograph equipment is not generally utilized to its fullest potential, and that alternative forms of monitoring are often overlooked in favor of criteria based on peak particle velocity alone. The new South Ferry Terminal tunnel and station comprised a 1,300 ft long excavation varying in width from 25 to 60 ft and 20 to 50 ft in depth. The excavation necessitated blasting adjacent to and underneath existing subway lines at several locations. A separate project currently underway and at a site located north of New York City, is also mentioned due to its wider variation of blast parameters relative to the more typical “urban” blast projects of New York City