Managing Rock Blasting Work in Urban Environments

In recent years, controlled rock blasting methods have been used to excavate rock in shafts, tunnels, and chambers at many projects at urban locations throughout the United States. For engineers, blasters, regulators, project supervisors, and managers, controlling blast-induced vibrations and air overpressure and other risks associated with this blasting is becoming an ever increasing challenge. For urban work, explosives security, storage and handling systems, overbreak control, impacts of blasting on green concrete, community relations, and the availability of skilled labor also influence the outcome of the work. This paper presents practical methods regarding blast design and risk management practices that have been used successfully at high-exposure projects located in or near Boston; Atlanta; Portland, Ore.; Milwaukee, Wis., and other cities in the United States. Special focus is on practical blast design techniques that mitigate blast-induced vibration and air overpressure generated by shaft and tunnel blasts. Controlling blasting impacts on concrete of varying age and placement condition is also discussed.