CVDG - Executive Summary
The Construction Vibration Damage Guide for Homeowners (CVDG)
Construction vibration damage to homes and other structures is increasingly recognized around the world as both real and relatively frequent. While there are no readily obtained, reliable estimates or studies of the occurrence of construction vibration damage worldwide or in the U.S., virtually every U.S. state and territory and nearly 90 foreign countries are among those reporting construction-caused vibration damage to Vibrationdamage.com. Such reports currently relate to well over 700 different construction projects worldwide.
When misused, or used properly too close to homes and other structures, heavy construction equipment can, and does, damage them. Those involved in or with the construction industry routinely say, in effect, that construction can't cause damage. Such statements are, at best, based on highly selective readings of the scientific literature and inappropriate application of clearly unsuitable vibration standards, if they are based on any scientific understanding at all.
Many construction contractors are responsible and mindful to avoid damage from their operations. Much of the far too common damage which occurs is brought about by operations performed improperly and/or in violation of both company policy and the use manual instructions for the equipment involved. Even some "properly done" construction operations, e.g. impact pile driving and use of vibratory compactors in compaction operations, are known to produce vibrations which can cause damage, if close enough to the nearby property and structures. There are well-known mitigation actions which contractors can take at minimal time and monetary expense to reduce or avoid damage.
Not all vibrations felt by people generate damage to structures. People can perceive vibration at about a factor of ten lower velocity than the lowest vibration standard for homes and other structures. Those vibration velocities which are sufficiently large to have a potential for causing immediate damage are higher than those usually encountered in normal life.
Construction vibration damage can take many different appearances and be both cosmetic and structural in nature. Cracking in wall finishes, both interior and exterior, is the most commonly observed damage manifestation (especially along approximate diagonals to wall penetration corners). Cracking is also sometimes accompanied by door and window misalignments, slab and other concrete cracking, masonry damage, damage to exterior property walls, plumbing and HVAC damage, and property damage separate from that done to structures. These damage types are often traceable to vibration-caused shearing ("racking") of the structure and its components. Damage may not appear immediately after the vibrations, but may take months to become fully evident, as the stresses produced by the vibration are slowly resolved.
Most ground vibration standards, and statements made about them, are ultimately based, to at least some degree, on extensive scientific studies of blasting vibration in surface mine and quarry operations. While there is much to be learned about vibration effects from blasting studies, blasting vibration standards are acknowledged in those blasting studies as inappropriate for construction settings, where, as with traffic, vibration can be effectively continuous for minutes, hours, weeks, months or even years in some large projects.
Continuous or long-lasting (more than "a few seconds") construction vibration enhances resonance and fatigue effects in home vibrations, which are far less significant in short duration, relatively infrequent and widely-spaced mine blasting events. Blasting vibrations last for a few seconds at most, less than the duration of the vibrations caused in a home by nearby blasting. Construction vibrations last far longer than the natural duration of home vibrations, allowing resonance and fatigue effects far more time to do damage through additive build-up of vibrations in the structure, a process referred to as "amplification".
Further, typical heavy equipment-caused construction vibrations have vibration frequency components which are mostly within the resonance frequency regimes of homes (below 40 Hz frequency), as is well shown by a set of Fast Fourier Transform-derived dominant vibration frequency data from a road reconstruction job involving virtually all the common types of construction heavy equipment. Ground impact-related vibrations are particularly worrisome in this regard. A quantitative analysis of vibrations from a road reconstruction project shows that integrated movement in construction vibration can be from tens to hundreds of times that generated in a "worst-case" mine blasting setting over the same period of time.
The limited existing research indicates that heavy equipment-caused construction vibration must be subject to much lower velocity limits than that originating from blasting. Construction vibration standards set substantially lower velocity limits for vibration than those set for blasting for that reason. Historic buildings and cultural assets require still lower vibration velocity limits. The relative scarcity of direct studies of construction vibration effects leaves many of the most critical scientific questions unanswered.
Homeowners with valid damage claims face many obstacles in handling their claims and pursuing repair reimbursement for damage done to their homes and property. Most home insurance policies carry exclusions for "earth movement", which are often invoked by insurers, with little scientific justification, to avoid paying claims in construction vibration damage cases. Construction companies receive complaints with some frequency about damage alleged to have been caused by their activities. They are experienced in dealing with claims and have money and legal resources to support their positions, placing the homeowner at an additional disadvantage.
Structure owners with damage must have extensive documentation of the damage and substantial evidence of a causal link to the construction activity to pursue a claim for damages. The best approach is to head off vibration damage problems prior to construction by documenting the house condition and registering your concerns in public comment meetings. A homeowner must give serious consideration to how to pursue a claim, perhaps even getting an attorney, if the damages will justify the expense.
There are currently few, if any, real checks and balances either to limit or remedy construction vibration damage. While science-based national vibration standards exist for various vibration sources, state and local implementations of vibration regulations are mostly limited or non-existent, making it difficult for those with damage to pursue their claims or for local agencies to stop risky and/or damaging work. In the end, we all pay a price for construction vibration damage, even if the burden falls disproportionately and unfairly on those whose homes are unnecessarily damaged by construction.
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