VIBRATIONS CAUSED BY TRAFFIC, CONSTRUCTION, AND BLASTING

This section covers Traffic Vibrations, Blasting Vibrations and Construction Vibrations. In addition, Vibration Recommendations are also included along with references.

Vibrations are found everywhere in nature and are generated by a wide variety of sources, both natural and manmade. They can propagate through air, ground, and water. Vibrations are used in geophysics to develop a better understanding of the subsurface, whereby vibrations are generated under planned and controlled conditions to gain specific objectives. The vibrations generated during geophysical data acquisition are normally imperceptible to humans and quickly attenuate once the surveys are completed. However, vibrations generated from other sources and for other reasons can be very perceptible and unwanted. The following discussion examines various options for measuring/monitoring, evaluating, and responding to unwanted ground vibrations from construction, blasting, pile driving, and other highway/transportation-related sources.

Many unwanted ground vibrations originate from natural sources such as volcanoes, earthquakes, and landslides. Since these events can be unpredictable and cause significant damage, they are considered in structural designs and building codes. An application of geophysics that addresses structural issues is seismic engineering observations, or the measurement of earthquake motions for comparison with structural design levels. Seismic engineering observations are real-time, continuous monitoring systems and have been installed on many critical bridges around the world. This is addressed in this document under Bridge Deck Structures - Stability.

Generally, vibration issues can be broken down into three broad areas: human perception, deleterious effects on critical processes, and physical damage, all of which can be important. For example, human perception becomes important in critical areas, such as near hospitals or residential neighborhoods. Vibrations can harmfully diminish the quality of Magnetic Resonance (MRI) images in a nearby hospital, or affect crystal growth in a semiconductor factory. Higher amplitude vibrations can cause physical damage to structures. Unfortunately, the procedures for measuring effects on human perception can be quite different from those used to measure effects on critical processes, or potential damage.