The hidden danger of construction

When you monitor vibrations, make sure it’s digital all the way!

Blasting, piling, drilling, demolition and earthmoving in conjunction with various infrastructure projects are universally known to cause vibrations. This, in turn, may result in costly damages to nearby buildings. To reduce any such obvious risks, building contractors often let specialized consultancy firms monitor vibrations around their building sites. 

Unfortunately, these efforts often turn out to be a total waste of money. 

In many cases the measuring equipment used is simply not sensitive and reliable enough. This will be painfully evident when property owners or their insurance companies present their claims for monetary compensation. Whether you are the builder or the property owner, the lack of precise and reliable documentation can be very costly indeed.

Working with the leading Danish consultancy company Grontmij A/S, Trine Kraemer is an experienced specialist in vibrations measuring:

“If and when a property owner demands compensation for cracks or other damages to their buildings, you must be able to specify exactly when, how and ultimately why the damage occurred. With the right measuring instruments you can prove exactly how strong the vibrations were, and where. And, importantly, the information will be safely stored, should anyone demand compensation, also months or even years later.

“Sometimes the greatest damages are not registered on the buildings that are closest to the building site, so you need very precise measuring data. And older, analogue measuring systems are way less sensitive than today’s best digital systems.

Analogue signals easily distorted
“A system may well be referred to as ´digital´ and have a digital data logger, but that is of no use if the signals from the sensor to the logger is analogue. In other words, they must be digitized as near the source as possible, before the vibration signals are distorted by analogue noise on their way to the data logger. ”

Several commonly used measuring systems do exactly that: they still send analogue signals from the sensors to the data logger which gives considerably less sensitivity and precision and thus more questionable documentation in case of a law suit.

“It’s just like the difference between an analogue and a digital mobile phone or TV set”, says Christer Svensson, founder of the Swedish instrument maker Sigicom: “You will notice the quality difference right away. The digital signals are crisp and clear. In the old, analogue phone or TV you may still see and hear distorted signals through the noise – and distorted signals is of course the last thing you would ever want in a measuring system.”

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