Wire (cheese cutter) barriers

**Ocean1** · 29th October 2007, 13:16

Originally Posted by Pixie

Why? They obviously didn't approve the barrier's installation,less than 0.5 m from the lane

Someone did, nowadays nothing happens without a formal safety analysis. The fact that such work still allows the installation of the likes of WRBs is a reflection of the regulatory framework rather than the engineering involved. The purpose of such safety analysis is to placate OSH, not to define best-practice safety procedures. Cynical? Me?

Originally Posted by Pixie

Mototub,as they use in France is tubing extruded in recycled plastic - around 300mm in diameter.
Two parallel runs, one above the other are attached to the posts

Like it.

**Ixion** · 29th October 2007, 19:27

Well, on Friday I departed darn Souf, to Terra Banjo. On passing down the Southern Motorway, I naturally took much notice of the cheescutters. And I observed, to my surprise, that Transit have, perhaps unwittingly, provided some of the cheesecutters with protection that would not make them entirely safe, but which would I, I think, help a lot. And which is pretty much free!

On one section of the motorway, not far from the recent crash site, Transit (presumably) have planted bushes along the line of the wire. I am not one who knows the names of all the various bushes or shrubs , but these are a very tight compact bush, that forms a ball shape about 6 to 8 foot in diameter, reaching to the ground. In some places they completely enclose the barrier on both sides. I stopped and poked one of the bushes, and it was a good strong woody thing , with close knit interwoven branches.

Now, in my misspent youth, I gained very great experience of the results of hurtling at high speed into all manner of vegetation. And believe me, nothing slows you down as effectively, but without serious injury as a good quickset hedge or cutty grass bush . These would be nearly as good as a hedge, and with 3 foot of vegetation on each side I'm sure that the slicing effects of the barrier would be greatly reduced (the branches break and compress up, and form a sort of mat.) .And at the same time a car hitting them , being heavier, would not rebound much if at all.

Improved safety, for free, and it's even environmentally positive.

**riffer** · 29th October 2007, 19:49

My god Les, I think you've discovered the answer!

And it's carbon neutral.

They're bound to go for it.

**tri boy** · 29th October 2007, 20:31

I agree.
Just goes to show, when in need of inspiration, turning to nature often brings results.

**motorbyclist** · 29th October 2007, 20:56

i read that a certain typre of thornless blackberry over in europe is being trialled as it will slow a car as effectively as it's brakes, and posed very little damage to bikers..

personally, i've seen guys jump off cars at 50kph into flax bushes are come out laughing... and dirtbikes are a good way to learn the cushioning power of vegetation

**Ocean1** · 29th October 2007, 22:05

Originally Posted by motorbyclist

personally, i've seen guys jump off cars at 50kph into flax bushes are come out laughing... and dirtbikes are a good way to learn the cushioning power of vegetation

Dude if Mum catches you riding in the garden shrubbery again she’s gonna be pissed.

But you’re right, in more civilised countries motorways and even freeways have medians many metres wide, usually planted with shrubbery very similar to a lot of NZ native bush.

**Sanx** · 30th October 2007, 00:56

Originally Posted by Ocean1

Dude if Mum catches you riding in the garden shrubbery again she’s gonna be pissed.

But you’re right, in more civilised countries motorways and even freeways have medians many metres wide, usually planted with shrubbery very similar to a lot of NZ native bush.

And what's more, those areas often become a wildlife haven. in the UK, you'll see kestrels hovering above motorweay embankments on a very regular basis. No-one ever goes there, so mice and voles come out to play.

I was thinking the same thing on the way home from Taupo last night, probably about the same set of bushes. However ... they take a while to grow and don't provide 100% coverage.

**cooneyr** · 30th October 2007, 08:19

The vegetation is a solution that Transit would lap up but I can see it not being applicable in all situations. There will be locations where sight distance will be a problem and other locations where digging up the pavement to plant the vegetation will potential result in issues with water getting into the pavement. Definatly another solution to push - Vegetation where applicable, Mototub on Armco and similar concept on WRB's.

I'm not sure there is need to manufacture a new product i.e. NZ version of Mototub. A product such as black LDPE or HDPE (Low or High Density Polyethylene known as Alkathene (not sure this is the right spelling)) pipe of the right diameter (up to 300mm diameter available here) . I would think a low pressure (thin wall) version of the pipe would have enough strength. It would come in rolls in the order of 50 to 100m long so should be easier to install than shorter lengths. Just need to find a suitable method of attaching it to the posts which I'm sure would be a piece of cake.

Anybody know how HDPE stands up to UV over a long time. Any farmers out there who have had a bit exposed on their farm for 20 years? The old man had some lying around on the farm for 10 or so years in the sun and it appears to be fine - hasn't become brittle yet.

Cheers R

**car** · 30th October 2007, 10:18

Originally Posted by tri boy

I agree.
Just goes to show, when in need of inspiration, turning to nature often brings results.

http://en.wikipedia.org/wiki/Psilocybin

**RiderInBlack** · 30th October 2007, 20:03

Originally Posted by Ixion

On one section of the motorway, not far from the recent crash site, Transit (presumably) have planted bushes along the line of the wire. I am not one who knows the names of all the various bushes or shrubs , but these are a very tight compact bush, that forms a ball shape about 6 to 8 foot in diameter, reaching to the ground. In some places they completely enclose the barrier on both sides. I stopped and poked one of the bushes, and it was a good strong woody thing , with close knit interwoven branches.
Improved safety..... environmentally positive.

Had thought this would be ideal in most greener areas of NZ. OK the hedging would need regular trimming so not "fee" or as cheep as some would think, but it would not only make the barriers more absorbing, but also "beautify" the barriers and the wire barriers would stop vehicles going right though the bushes.

**Ozzie** · 30th October 2007, 20:37

The problem is only that it is very patchy.

The bit where Dan met his fate, 100 meters either side has these things.

They are a good idea, but, to be effective, like anything else, they need to be consistent.

These aren't.

Without regular maintenance, they become sparse, patchy, inconsistent and ineffective.

We need, as much as ever, someone to not make a half arsed attempt, be consistent, and basically, Give A Shit!

**sunhuntin** · 30th October 2007, 20:49

suitable where there is already a few foot of grass verge, but cant see it workin on the wellington road.

**motorbyclist** · 30th October 2007, 20:55

i see concrete working there better than wire

**Ocean1** · 30th October 2007, 21:24

Originally Posted by sunhuntin

suitable where there is already a few foot of grass verge, but cant see it workin on the wellington road.

Yes, most places I've seen them there's minimal room, probably the reason they're there in the first place.

I think that's the core problem, there's simply inadequate seperation between opposing traffic flows on almost all of NZ's main roads. The trend overseas has been towards green medians some 10 to 15 metres wide for many years.

NZ's very wrinkled though, a challenging shape on which to construct or widen roads, and we have a lot of miles of road for our population. That makes for a comparitively high cost, and while widening roads to include a broad median is probably the "correct" fix it's simply not going to happen any time soon.

Having said that it's obvious that a lot of WRB installations are far closer to traffic than most authorities advise. It looks very much like a cost/benefit equation based on an inadequate budget. I don't think the modifications discussed so far represent an inappropriate expectation. Expensive certainly, but if the cost of the WRBs is what I've heard ($700K/Km) then it's hardly a massive increase to what's ultimately been a cheap solution in the first place.