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Flexible Safety Barriers

Flexible Safety Barriers form an important part of DIER's 'Safe System' approach to road safety.

DIER uses Flexible Safety Barriers which is a high-tension wire rope cable.  It can be used on a medium strip or down the middle of a road to prevent head-on collisions; or along the edge of road shoulders to prevent run-off-road crashes.

The benefits of flexible safety barriers

Tasmania has a history of head-on and run-off-road crashes and Flexible Safety Barriers contribute significantly to improving the road environment so that persons have a greater chance of surviving a crash on Tasmania's higher speed roads.

The Flexible Safety Barriers helps to restrain an out-of-control vehicle.  Used on medians or down the middle of the road, a Flexible Safety Barriers stops an out-of-control vehicle from crossing into the path of on-coming traffic, preventing head-on crashes.  Used at the side of the road, the Flexible Safety Barriers prevents out-of-control vehicles from running off the road and colliding with road side hazards such as poles and trees, helping to reduce the severity of the crash.

Flexible Safety Barriers are effective at containing out-of-control vehicles within the road environment.  The flexible nature of the Flexible Safety Barriers helps absorb the impact energy, reducing the risk of serious injury and damage in the event a vehicle crashes into the Flexible Safety Barriers.

Experience has found that wire rope safety barriers can reduce the likelihood of a crashing vehicle rolling over as the impact of a vehicle is absorbed, rather than 'bouncing off' a more rigid barrier.

car

The 'Safe System' approach

'Safe System' is a term that is used throughout Australia, New Zealand and worldwide.  It represents a shift in thinking about road safety where the road system is looked at as a whole, ie road users, the roads and roadsides, the vehicles and travel speeds.

Safe System is based on the Swedish 'Vision Zero' and the Netherlands' 'Sustainable Safety': two countries leading road safety initiatives.  The System design is built on the ethical basis that nobody using a road should be seriously injured or killed and that road authorities should strive to eliminate fatal and serious injury crashes by adopting a more holistic system approach.

The Safe System approach recognises that people will make mistakes ‐ even the best drivers in the best cars will at times make mistakes - and that the human body is frail and can only tolerate a certain amount of energy in an impact before it is seriously damaged.  A Safe System approach can help to prevent crashes occurring, but where they do occur helps reduce the energy that's involved in a crash to that which the human body can tolerate.

The Safe System has four cornerstones:

  • safe vehicles
  • safe road users and behaviours on the roads
  • safe speeds
  • safe roads and roadsides

This means that where there is better road infrastructure higher travel speeds can be set.  For example, the use of safety barriers in a Safe System road design allows for higher speeds where it is safe to do so.  Safety barriers help reduce the risk of crashes occurring and manage energy in crashes that do occur. Safety barriers are very important because they separate opposing traffic and they protect out-of-control vehicles from hitting roadside hazards such as trees, poles and ditches.

In terms of the types of safety barriers, the issue for road designers and engineers in designing projects is to think about the most appropriate response to the problem in that area. There are different types of safety barrier systems available but the wire rope safety barriers have been proven to be the safest when crashes occur.  Studies overseas have found an 85 per cent to 90 per cent reduction in serious casualties where Flexible Safety Barriers have been installed. 

Flexible safety barriers and motorcyclists

It is recognised that the motorcycling community has concerns with flexible safety barriers.

Motorcyclists are vulnerable road users and research shows that flexible safety barriers are no more hazardous to motorcyclists than other types of safety barriers.

DIER and the Tasmanian Motorcycle Council (TMC) work collaboratively to address what type of barrier should be used in what location.

In the event of motorcyclist crashes, a person hitting the posts is more of a concern than hitting the flexible barrier.

rub railbarrier berrier close
DIER and the TMC have agreed that on high speed tight radius curves DIER will consider using a steel W-beam, fitted with a rub rail.  The rub rail is an extra piece that fits along the bottom of the W-beam and prevents a motorcyclist who loses control from hitting the post.On slow speed tight radius curves DIER will install Flexible Safety Barriers with padding around each post; this will help reduce the effects or a motorcyclist colliding with a post in the vent of a crash.