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I'm sorry, but is it not pointless to put up concrete speed barriers on the highway/freeway? Answered

I've seen that most vehicles (besides motorcycles, who usually send the rider over them) can generally go through the barriers at highway/freeway speeds.  In the US, particularly Arizona, even more particularly Phoenix, the cars will plow through, I've noticed, the speed barriers.  Please, correct me if I'm wrong.


I don't know what "speed barriers" you're referring to -- I can't think of anything called that here on the East Coast -- but I suspect that if they really had no effect, money wouldn't be being spent on 'em.

You folks call them "Jersey barriers"; out West we know them as K-rails. According to the Wiki page, not all the ones you see are technical K-rails. There's some slightly different dimensioning called an "F-shape barrier", but at 100 klicks they all look pretty much the same.

Military slang for both kilometers and kilometers per hour, determined by context, as in "Our target is objective A, located 25 klicks NNE," or "Whoa! That tank must've be going 30 klicks across the sand!"

Uhm. Jersey barriers don't have anything to do with speed, except that they scare some drivers. They're a replacement for guard rails, either temporary modules (eg during construction) or permanent cast-in-place.

If that's what is being referred to, they certainly aren't pointless -- they _do_ keep cars from crashing through about as well as anything can be expected to, and they're safer than some of the alternatives for that purpose, though ugly. (They do a lot less damage to the car and occupants, and the car does a lot less damage to them, in a glancing blow than sometimes happens with metal guard rails, for example -- and on a highway most of the accidents they have to catch will be exactly that kind of tangential impact.)

Could the Original Poster clarify, please? If you can post a photo, or point us to one, that might help us all agree on what we're talking about.

. I think s/he is talking about the barriers placed in medians to keep opposing lanes separated.

Even if a speeding vehicle could plough through the barriers (which I doubt), the vast majority of collisions at speed will be glancing blows.

You may want to research the engineering design and criteria of K rails. That will give you some real facts to back up your claims, or it might change your naive impression.

Sure maybe 1 in 100 go thru of over them but they keep the other 99 from running headlong into on coming traffic.

They also have the effect of making some people drive more carefully so as not to run head long into a concrete barrier.

How long have you been driving?

Yes, they serve a dual purpose. One is physical the other is mental. Just having something there will tend to keep people in their lanes where they belong. Its easier for many people when they have some kind of guideline. That's why they spend a fortune on lane markers, its not decoration. They help people to understand what their boundaries are. We are not supposed to be driving like bumper cars where you just bounce from one obstacle to another. The idea is to not hit them. For those who fall asleep, or somehow loose control the barriers are the last resort to try and prevent disasters.

I know them as Jersey Barriers and they come in many different sizes. An ongoing DOT project in my area is replacing the original strongpost guiderail with the large version, which seem to be between 5-6 feet high and several tons of hardened re-inforced concrete. Every place I have seen where they have done this replacement, the danger to oncoming traffic has been greatly reduced.



7 years ago

Yea.....  your right about that.
I tool around in the Sierra mountains.
To me it's like a WPA project.
Keeps some guys working on my nickle ¥
Have a good one.