These things are turning up because they are really cheap.... half the initial installation costs and then repair is VERY cheap... few plastic guides which attach to the ground and then re-strain the wires...
so simple a kid could do it... or 4-5 council workers
Also, for what they are designed to do -stop larger vehicles leaving the roadway- they are quite effective.
For parrallel impacts (rubbing a car/truck alongside) eg when a driver falls asleep......
they'll make lots of noise to wake the driver and keep them safely away from trees, livestock etc.
I'm doubtfull that for a frontal impact (hitting with force directly at them) eg when a driver loses it on a bend and ploughs straight into them, wether they'd do squat.
We've all seen them after they have had an impact.... how saggy they are... if you hit them straight on i'm fairly confident they'll strech up and over the bonnet, and possibly the whole car. I hope no-one has to find out the hard way..... especially on some of the bends with cliffs behind the barriers!!!!
They do push the vehicle downwards, hopefully that is enough to drag the belly of the car on the ground enough to slow you down!!!
The other possibilitys are -they could break having little effect, or do what the clip shows - no good outcomes whatever happens!!!!
As for the clip, if you look at 34s to about 54s you can clearly see a radiator hose spewing hot steam in the upper lhs, means they had a real motor in them.... the barrels on the back are probably to add weight, (more force to push the truck into the "linebacker") and cause more damage.
Ultimately, if we all drove cars, they'd be ok, but then if we all drove cars why don't we all just drive safely and there'd be no need of safety barriers in the first place!!!
Or, we could take responsibility for our own actions and when we do get hurt, stop whining about our injuries and get on with life.
Alternatively, look up the "pensioners" thread.... free medical sounds good!!!
Well, that's my rant done for the day! and it's all my own opinion.... no one has to agree with me, but I sure think I'm right!!!
Also if you like linebackers check out this:
http://www.youtube.com/watch?v=RzToNo7A-94