The Construction Vibration Damage Guide (CVDG) deals mostly with ground vibration effects caused by construction heavy equipment, with some considerable discussion of blasting-generated vibrations and their effects on structures. However, there are several other sources of vibration which can interact with homes. While they are not central to the discussion of construction vibration in the CVDG, a brief discussion of some of the most common other vibration sources encountered by some home and building owners follows. The purpose of this discussion is to provide people who are experiencing vibration effects from non-construction sources with some starting points for their own investigation.
Traffic on streets and highways can be a semi-continuous source of low-level vibration. Depending on the distance of the structure from the road and the type, speed and amount of the traffic, vibrations may be felt, particularly from passing large, heavy trucks (e.g. semi trucks). It has long been recognized that the semi-continuous nature of traffic vibrations requires lower acceptable peak particle velocities than those acceptable in short duration blasting.1
Traffic vibrations are often used by contractors as rationalizations for damage done by road construction projects (see Counterarguments in the CVDG Pro for more on this). One 6-month road construction job involved work on moderately busy city streets with both car and large truck (no semis) traffic. After initial extensive damage was done by the contractor pounding on pavement with an excavator, vibration monitoring was started.
That monitoring was very poorly done. It lacked any "baseline" measurements of weekend or night hours when no construction was occurring. However, some breaks in work during lunch periods and at the end of days after stoppage of construction allowed an estimation of the contribution of traffic to vibration. The construction activities included excavation with a large excavator, laying of water main and backfill with the excavator. Looking at the histogram record, shown at left, of one such day's work, pre-construction start, the lunch periods and post-construction-work periods stand out as being strikingly low in vibration, even though these are among the busiest traffic hours on the street.
In all cases, where even heavy truck traffic (e.g. full large trash pickup trucks as at right, note blue seismograph box just behind truck at left of photo) went as close as two feet from the seismograph head, no vibrations above normal "background" were detected.2 By contrast, even the heavy equipment with the smallest vibration-inducing properties produced vibrations which averaged 3-4 times the background velocity level.5 Thus, a typical mix of car and truck traffic on a residential city street is often of relatively little concern from a vibration standpoint, even if you occasionally experience vibration in your home.
This picture could change if you live very near an interstate or any other highway with large amounts of semi-truck traffic. Because such vehicles both weigh a great deal and travel at high speed, the potential exists for accumulated vibration to create some damage over a period of years. Again, the mere fact that you feel some vibration does not imply causation of damage, by itself. A good source of information for those who have concerns over traffic-caused damage is the High-Speed Ground Transportation Noise and Vibration Impact Assessment of the Federal Department of Transportation. Our More Information page carries a link where you can download a free copy of it.
Anyone who has sat in a car at a rural railroad crossing knows that passing trains can produce vibration. However, the cases of most concern are those where railways are present in cities, either to move freight or as part of a mass transit system. Many factors come into play in determining whether train traffic can cause damage in buildings, including those associated with the building (age, construction, maintenance), those associated with the site (distance from railway, soil and bedrock properties) and those associated with traffic on the railway (condition of track and bed, age of track and type of rolling stock, and weight of train cars), among others. Because there are so many factors which relate to damage potential in these situations, it is often difficult to predict which ones will be prone to inducing damage. Again, one of the best sources for information on railway vibration is the High-Speed Ground Transportation Noise and Vibration Impact Assessment of the Federal Department of Transportation.
Some cities (e.g. New York City) also set vibration standards for railways. Because railway vibration is semi-continuous, these standards tend to be much lower in peak particle velocity than those set for blasting or even those which currently govern construction vibration (e.g. the highest allowed PPV in New York around railways can be as low as 0.05 in/sec, depending on the surrounding structures).
"Fracking" and Oilfield Wastewater Disposal
Hydraulic fracturing ("fracking") of oil and natural gas-bearing rock formations is a subject of much current controversy with respect to generation of small earthquakes and, on seemingly rare occasions, relatively minor damage to structures. Fracking involves pumping at high pressure a complicated mixture of water, sand, surfactants ("detergents") and other additives into oil or gas-bearing rocks at depth in order to crack the rocks and release the trapped petroleum components for recovery. Any technology capable of breaking rock at depth has at least a potential for causing vibration similar to small earthquakes. There are only a few documented examples where fracking is thought to have caused small earthquakes and minor home damage. Damage to structures from fracking operations is controversial, but rapidly becoming accepted in the scientific community as at least possible. It is probably best to conclude that it is unlikely, but not impossible in some instances.
Oilfield wastewater disposal is often confused with fracking, because it has some similarity with fracking in terms of equipment and its effects. Wastewater disposal often involves pumping the water at high pressure into rock formations, cracking them as a result. One state in the U.S. in particular, Oklahoma, has experienced a large increase in earthquakes, some damaging to buildings, which correlates with increased oilfield and shale gas production activities there - mostly wastewater disposal. Several scientific studies have indicated a link between increased seismicity (earthquakes) in Oklahoma and oil production activities there. Other U.S. states have experienced increases in seismicity around fracking-type activities, but their real impact on structures remains controversial. Predictably, those in the oil industry, much like those in the construction industry with respect to construction damage, argue that fracking does not damage homes.
There are other concerns regarding fracking and wastewater disposal in oil and shale gas fields, including the potential for ground water contamination and ground water use in generally arid areas in the U.S. West. These concerns cannot be ruled out completely, though they seem less well-supported than the seismic issues identified in Oklahoma and elsewhere. For a good layman's introduction to fracking and other oilfield-related issues, there is a helpful series of National Geographic articles available online.3,4
Machine tools with rotating or reciprocating parts, like lathes, turbines, stampers, forgers and many other types also produce vibrations, the intensity and frequency distribution of which depend on the tool, its operating speed and whether it is rotary or impact in nature. Since vibration in rotating devices wastes energy, there is a whole field devoted to measuring and reducing machine tool vibration. If you live very near a steel mill, foundry or other large manufacturing facility, machine tool vibration may be detectable on your property. Its transmission through the ground can be measured on the property using the same instrumentation used for construction vibration.
Other Sources of Vibration
Homes can experience occasional vibrations from many sources in addition to the ones discussed here and elsewhere in the CVDG. Sonic booms, activities of people in the home, and even some home mechanical systems can all be sources of vibrations. However, most of these are simply too localized, too small, or of too short duration to be much of a factor in causing significant home-wide damage in the overwhelming majority of cases. Therefore, such sources can be discounted in most cases as likely causes of significantly damaging vibration.
There are, of course, many sources of vibration beyond those mentioned here. Many of these produce near-continuous vibration with relatively low velocities (intensities). When evaluating the potential for damage for such a near-continuous source, the frequency distribution of the vibration components is at least as important as the vibration velocity (PPV). Because homes respond differently to different frequencies, especially those near the home resonance frequencies, even small vibrations near those resonances can be dangerous to a home, if they persist long enough. Vibrations which have a broad spread of frequencies, particularly ones generated by impact or impact-like activities (e.g. driving of tracked equipment over distances), are virtually certain to lead to amplification of the vibrations in homes. Thus, understanding the true frequency distribution, best gotten from FFT analysis of the vibration waveform, is critical.
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