Tag: Falling Weight Deflectometer testing
Falling weight deflectometer (FWD)
by Ian on Dec.27, 2008, under Materials and Construction
Did I mention I had two of these machines? a light weight FWD (Prima 100) and a trailer mounted Dynatest FWD. Well not actually mine but of course my companies. What my beef today is Transport Scotland’s specification that requires FWD to HD 29, ie trailer mounted. Well first you need a departure to the more appropriate hand held FWD for subbase and formation, why, because HD 29 describes the trailer mounted beast. Not the least of this post’s beef, it’s the effect on the program, using the trailer FWD, waiting for base and binder to cool to less than 30 oC , ideally 20oC; tie ins are a problem, short trunk roads are a problem, trying to accelerate a program is a problem. The blooming use of the FWD is a problem, can a designer really analyse FWD data on freshly laid but cooled blacktop and confirm it complies with his design? If it is anything like the precision of the ITSM (NAT) test, then I can answer that question, forget it! It is just about possible to describe it as accurate.
Let me say I am not against testing, it’s my background, but testing that results in delays to a contract for a pile of data that means zero? And lets face it you and me as tax payers do pay for this data collecting, and we do have the freedom of information act.