Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Flexible barriers: How they work and the 'cheese cutter' myth

Discussion in 'The Pub' started by jdkarmch, Jan 15, 2016.

  1. Found this little bit of trash on FB today

    I would recommend that we should all visit this link and leave a comment. I have.



    Improving road infrastructure is a vital part of the Towards Zero approach. $1 billion is being invested into making Victorian roads safer for people to use in the Safer System Roads Infrastructure Program (SSRIP). As part of SSRIP a number of centreline wire rope safety barriers, or flexible barriers as they are also known, are set to be installed on high risk rural roads, such as the Goulburn Valley Highway.

    Find out more about SSRIP.

    Flexible barriers can stir up emotive debate about their effectiveness at protecting road users and the potential risks for motorcyclists. While some concerns are valid, at times a misinterpretation of facts surrounding flexible barriers has people worried. Below, we address many of the concerns and questions raised about flexible barriers based on research conducted in Australia and overseas.

    What are Wire Rope Safety Barriers and how do they work?
    Wire Rope Safety Barriers, also known as flexible barriers, are road barriers made up of four tensioned wire ropes supported by steel posts. They are described as 'flexible' because they stretch and absorb the force of the crash. The barriers use a dual mechanism to slow down and divert excessive force away the people inside the vehicles. The ropes deflect and absorb the energy and the posts collapse, slowing down and redirecting the vehicle away from the hazard with very little rebound. The flexible barrier is the most forgiving system with people more likely to walk away after their car crashes into it than other available road barriers.

    How are they tested?
    Most flexible barriers are developed around the world. VicRoads assesses and accepts different products based on the US examination standard because they have a similar mix of cars on the road to Australia (from smaller to heavy vehicles).

    The tests simulate the worst practical conditions of crashes with the barrier in terms of angle and speed. They include:

    - 820kg car (eg a smart car) travelling at 100km/h hitting the barrier at a 20 degree angle

    - 2000kg car (eg a ute) travelling at 100km/h hitting the barrier at a 25 degree angle

    - 8000kg truck (eg a heavy rigid truck or bus) travelling at 80km/h hitting the barrier at a 15 degree angle. The video below demonstrates one of these tests.

    Why are we installing flexible barriers?
    There are three types of barriers that we generally see on our roads: rigid concrete barriers, semi-rigid Steel W-beam barriers and flexible wire rope safety barriers. Research conducted by Monash University Accident Research Centre (MUARC) shows that flexible barriers are superior compared with concrete and Steel W-beambarriers because of the way they dissipate the energy of the crash away from people in the cars, their deflection levels and the way they contain the vehicle. Centreline wire rope barriers are now being specifically used and are effective at preventing head-on crashes, i.e. when a vehicle crosses the median strip into oncoming cars (such as in the Towards Zero Now & Then ad).

    Loss-of-control crashes are a major contributor to deaths and serious injuries on our roads. MUARC's research evaluated 100km of wire rope barrier across Victoria and their findings suggest they are responsible for significantly reducing the risk of death and serious injury in crashes. Their results, consistent with studies conducted overseas, estimate all crashes have been reduced, including run-off-the-road and head-on crashes, on individual routes upwards of 75%. On the Hume Highway and Eastern Freeway the estimation is even greater, up to 87% and 83% respectively.

    At the end of the day, you are more likely to walk away – or as the below photo shows, drive away – from a crash with a wire rope safety barrier than any other barrier system.


    The photo comes from the Melbourne bound carriageway of the Western Highway at Anthony's Cutting. Here the flexible barrier has stopped a vehicle from crashing over a steep embankment with potentially deadly consequences. Instead the vehicle was able to drive away from the site without intervention from VicRoads (i.e. VicRoads don't have any driver or vehicle details relating to the incident).

    Aren't they banned overseas due to concerns about dangers to motorcyclists
    There is a common misconception that flexible barriers are banned in some places in Europe because of the danger they pose to motorcyclists; this is not the case. In countries such as Denmark and Norway, governments have either ceased installation or banned the barriers due to political pressure from lobby groups. But, there is no scientific research to show flexible barriers cause more deaths and serious injuries for motorcyclists. Swedish studies have shown there is actually a 40 – 50% reduction in risk of being killed for motorcyclists with wire rope safety barriers. Flexible barriers are being installed world-wide by countries seeking to reduce trauma on their roads, including Sweden, the USA, New Zealand and Australia.

    The 'cheese cutter' myth
    The 'cheese cutter' myth is thought to have been spread after an incident in New Zealand where 21-year-old Daniel Evans was fatally injured striking a road side wire rope safety barrier. News reports at the time suggested the wire rope barriers presented a similar danger to other motorcyclists. On reading the following coroner's report about Daniel's death it was found that speed was a major factor. It was calculated Daniel was travelling between 148 – 190km/h when he left the road, which resulted in an impact speed the equivalent of jumping off a 13-storey building.

    While barriers of all kinds are designed to protect people from hazards, either on the side of the road or from oncoming traffic, they still pose a risk to the vulnerable human body and experts acknowledge their risks. They are only installed where the risk of crashing into the barrier is much less than the risk of hitting the hazard from which they are shielding. Motorcyclists are particularly vulnerable to injury in all crashes due to the limited protection their bodies have (similar to that of a pedestrian) compared to someone in a vehicle.

    Flexible barriers pose a risk to motorcyclists because of their steel posts rather than the wire rope as commonly thought. (W Steel barriers also have this risk.) The posts are designed to bend for vehicles, but not people, and generally, motorcyclists will come off their bike and slide under the wire or into a post. Raphael Grzebieta is currently the professor of Road Safety at the Transport and Road Safety (TARS) Research unit at University of New South Wales and has done extensive research on wire rope barriers and motorcycle crashes. In the coroner's report into Daniel's death he is quoted as saying:

    "The term 'cheese cutter' refers to the performance of roadside barriers made of cable wire rope or high tension wire held by posts. The idea of the 'cheese cutter' effect is a 'myth'. It appears that group of misinformed motorcyclists perceive these types of roadside barriers as a hazard providing less safety than other barrier systems such as concrete or guardrail systems.

    "There is no evidence to date anywhere in the world of motorcycle riders travelling at or below the posted speed limit, and who has crashed into a wire rope barrier, being cut by the wire rope in a manner similar to how cheese is cut with wire…"

    In Sweden, they have more than 600 km of flexible barriers on their roads and no records of motorcycles being 'sliced' by the barriers. Instead they have seen a 40 – 50% reduction in risk for motorcyclists being killed since introducing wire rope safety barriers. That being said, flexible barriers are not the barrier of choice for routes used heavily by motorcyclists or on tight curves; those without exposed posts such as Steel W-beam attached with motorcycle rubrail are the preference, but these offer less protection to vehicles than flexible barriers. Where new flexible barriers are installed in Victoria, they can now be fitted with cushioning and posts are created to have a wider surface area to lessen the impact force. Research is also currently being conducted to find a way to shield the posts or find alternatives without compromising the barriers' benefits.

    It's important to remember that barriers also prevent motorcyclists being injured by other vehicles too. In the below video, filmed on one of Sweden's 2+1 roads, the wire rope safety barrier stops a car from having a head-on crash with a motorcyclist riding in the opposite direction.

  2. Interesting, They have tested with a smart car, a Ute and a truck and then make the claim it is safe for motorcycles even though it is not one of their test vehicles.

    I have corresponded with Raphael Grzebieta professor of Road Safety at the Transport and Road Safety (TARS) Research unit at University of New South Wale. His understanding of the issues was underwhelming to say the least. His trite response to my enquiry was one of those "no evidence from crash data". Absence of evidence is not evidence of absence Professor Grzebieta.

    My response to these things is that I take note of every broken post every loosely strung wire every failure in installation and report them to VicRoads in writing. My goal, perhaps a naive one, is to increase the maintenance expenses of these installations and thus their total cost of ownership (TCO). Road designers see these as a cheaper alternative to W beam barriers with underrun protection.
    • Winner Winner x 3
    • Like Like x 1
    • Informative Informative x 1
  3. First there is no data, and then there is, makes me feel nice and safe. And I am happy my bike wont hurt anyone as well.
  4. I wonder if they realise that by quoting research from MUARC, this taints every other aspect of the article even if the other aspects are demonstrated or true? At least to me anyway.
    • Winner Winner x 2
  5. The links provided in that piece of propaganda are telling in themselves; e.g. the link (used twice) to an NZ Coroner Report on a motorcycle fatality where the rider lost his leg to a WRSB. That is offered as 'evidence' by the TAC article of political interference in the use of WRSB in Norway, FFS!!! And the reference?

    Now I don't know about you, but a 5 year old NZ Coroners Report referencing a professor from NSW stating something 'appears' to be political doesn't quite sit as well as it should.

    Again, there is bugger all motorcycle related research quoted anywhere in this. Time that the TAC got back to proper communications and reference with the likes of the VMC.
    • Agree Agree x 2
  6. Rope, steel post, whatever. If one limb goes one side and another body part goes the other, it is not going to end well.
    W Steel Barriers with under-run protection pose zero risk of dismemberment.

    No mention of the 'cheese grater' effect. That of sliding along a steel rope and hitting each retaining post along the way, progressively causing more injury.
  7. I reckon running into any roadside furniture is never a good plan.
    Ride to the conditions includes noting hazards presented by hard objects on the roadside.
    • Agree Agree x 2
  8. That video at the end. Did anyone watch their justification for how its saved a motorcycle rider?
  9. Yes ...
  10. Utter puss.....

    Next question?
    • Like Like x 1
  11. While I was reading that I was thinking to myself that maybe they're not as dangerous as what I've heard.

    But then I realised the source of the information, and the credibility they've had in other areas which threw doubts straight away. Propaganda or truth - I really don't know, but given the history that I know of their credibility in other areas, it pretty much means I can't depend on what's been written...
  12. On the other hand the report


    co authored by our friend Professor Grzebieta. when he was at the much loved MUARC says

    Simulations of the wire rope barrier collisions
    showed that regardless of angle or speed it is
    unlikely that the motorcyclist will clear the barrier
    very cleanly. In many cases the motorcyclist’s
    extremities became caught between the wires. This
    results in the rider being subjected to high
    decelerations and possible high injury risk
    secondary impacts into the road.

    In all the simulated wire rope barrier collisions, the
    wires guided the motorcycle into the posts leading
    to heavy contact with the post. The motorcycle and
    the rider were subjected to large decelerations
    because of this snagging effect and hence elevating
    the injury risk for the rider
    • Informative Informative x 7
    • Agree Agree x 1
  13. You beat me to it - the question is what further research has been done? .
    • Like Like x 1
  14. That all sounds horrific
  15. copied to their FB page. Hope that's okay chris
    • Like Like x 2
  16. Like everything the 'Monash University Accident Research Centre' release it seems to be based off half truths with their always being a stinky smell about who actually benefits from the results or what's it being used to justify this week.
    In this case I can almost certainly tell you its the cheaper cost of the barriers compared to proper separation of the roadways or building a large 'bugger off' cement wall' which will stop anything upto a battletank.

    I've seen riders and cars run wide and clip metal or cement walls and recover. Wire barriers are designed to snag the car or bike+rider and rip them to pieces to bring them to a stop.
    That video is the biggest joke, any barrier would have prevented that, you can't say a wire barrier is 100% safer compared to no barrier where they run off the side of a Swedish cliff-face or head-on into another car!
  17. What a load of bullshit. The photo where the car hit the rope and didn't go over the embankment would have had the same result with Armco.
    The "test" with an 8tonne unlaiden truck shows that it still went a couple metres onto the other side of the road. More than enough to still have a head on.
    They are very unlikely to stop a fully laden truck unless it veers off the road at a shallow angle.
    We have them being installed alongside roads that have a dropoff on straight roads. At what cost? If thousands/millions of drivers can drive along a straight road
    without running off the side why do we need to spend money on barriers that are not needed.
    I might be cynical but i suggest that someone in RMS and or councils is getting a kickback from the companies supplying these unessecary WRBs.
    • Agree Agree x 1
  18. Those wire rope barriers look nasty ... best not crash into them ...
  19. Agreed. There are quite a few in this part of the world, and they're quite effective in getting me to corner more slowly.