Vibrationdamage.com

An unacknowledged risk of damage

If you read the scientific literature of construction vibration damage to structures, you'll find that most of it attributes damage risks to three main sources: construction and mine blasting, pile driving, and vibratory compaction of soil and asphalt. Little attention is given to demolition procedures generally, which can produce damaging vibrations from various sorts of ground impacts. No mention at all is given to "pounding" with an excavator or backhoe bucket to break pavement, rock or hard soil.

I have previously pointed out that there is little if any, published data on the vibration velocities associated with this type of construction operation. This is true probably because it is explicitly banned by most contractors, for the reason that it is "hard on the equipment". Although no reference velocities (PPV's) for such powered pounding are available, they are available for unpowered weight dropping operations like "dynamic compaction" and "crack-and-seat") used to break pavement. The published velocities for these operations are FAR beyond any blasting or construction vibration operation, ranging anywhere from 3-8 in/sec.

Not only have we observed pounding of this sort in action, we have come to realize that it is common. The original damage to my own home was done by pounding on asphalt pavement. After notification of the damage and its cause the contractor continued to do it - until they were forced to institute vibration monitoring. I could calculate from known resistances of materials to vibration damage that the minimum reference PPV from the vibrations produced in the initial instance were over 10 in/sec - more than 50 times the FTA limit for timber-framed homes of 0.2 in/sec.

Since that time, 5 other contractors have come to the same intersection - mostly to repair the shoddy work done by the original contractor. I have had to stop 4 of the 5 crews from pounding on the concrete or asphalt, pointing out the vibration risk. ALL of those then continued with the pounding after I left them. Note in the photo below of the most recent incident that the "teeth" of the excavator bucket are located over the pavement, not the dirt. The photo shows the crew had on site with them the exact equipment needed to lift and overturn the pavement in pieces. They chose not to use it.

Their company was sued 15 years ago for its role in a job which caused extensive damage to numerous homes. Thus, one could reasonably conclude that they cared more about their work than they did about the real possibility of damaging homes.

My experience is seemingly common. At least 70 people have reported to us at Vibrationdamage.com similar excavator or backhoe pounding on pavement as the likely cause of damage to their homes or structures, always in the absence of any vibration monitoring. Monitoring would almost certainly raise a red vibration flag for the crews.

If you experience this kind of pounding by construction crews and your home is within 100 feet of the work, you should assume that there is a high probability of damage. Immediately contact the construction crew and advise them to stop what they are doing. Follow up immediately with a notification to their company. You should also begin documenting by photo or video everything done by the crew. There are many other ways to remove pavement without such vibration risks, including getting under it with equipment of the sort shown in the photo, picking it up in pieces and hauling it away.

Vibration damage and Homeowners' Associations (HOA's)

Many homeowners are members of local HOA's. When there is widespread damage among the members' homes, you may consider involving your HOA in making vibration damage claims for all those affected. This can increase your leverage in finding a non-litigation solution for the damages, but is not without problems.

It may be difficult to get your local HOA to vote in favor of concerted action. Many people do not want to be involved in claims, even if they have damage; others who think they don't have damage may be unwilling to support your claims. There is a good chance that some member of the HOA will reveal information to others that you would not like revealed.

If you involve your HOA in helping make your claim, you will have to do some work in building support within the HOA. This will take time, but it may have value in finding out not only who has damage, but who is unwilling to support any claim. At the very least, you will build awareness by bringing your claim and concerns to the HOA as soon as possible.

Send a message to learn more

Equipment reference PPV's

Far too often, perhaps in a majority of cases, vibration monitoring is not done during a construction job in which there are damage claims involving surrounding properties. Then, vibration PPV's can only be estimated, using measured distances to the work, records of the type(s)( of construction equipment used, and reference PPV's found in several reference works, including our free Construction Vibration Damage Guide for Homeowners. With these data, PPV's can be approximated for construction equipment or blasting, employing vibration attenuation equations of the sort built into our free Ground Vibration and Safe Distance Calculators (https://vibrationdamage.com/vibration_calculator.htm).

However, one needs considerable care in employing calculations to estimate PPV's. First, such calculations with the simple equations usually employed are only accurate to within about a factor of two. Second, the reference values usually quoted date back to 1980, when most construction equipment was smaller and less powerful than current types, thereby likely underestimating the PPV. Third, most types of equipment, especially compactors used in road construction and development, have many operator adjustable parameters which can affect both the PPV generated and calculated. Fourth, some types of equipment, including pile drivers, have different energy classes, which determine the amount of vibrational energy transferred to the ground. Sadly, many of these critical parameters are either unknown or exceedingly difficult to get for the situation at hand.

Whether you're a homeowner trying to get handle on what vibrations might have been in a construction job or an expert trying to render an opinion based on such reference values, keep in mind always the need for the factor of two accuracy range of such calculations. Any vibration PPV within a factor of two of a properly chosen construction vibration standard should be seen as capable of doing damage to structures.

Send a message to learn more