Shockingly, in more than half of regional casualty crashes where the vehicle leaves the road and hits an object, it will collide with a tree.

So, what needs to be done to prevent these collisions with objects on the side of the road? Cut down trees on the roadside and remove hazards like Stobie poles and light posts?

While this measure can often solve the problem, there can be environmental or economic reasons as to why it can’t be done. Thankfully, there’s another solution that can reduce the severity of these crashes and save lives.

If you’ve driven in regional South Australia over the past few years, you might’ve noticed safety barriers being constructed on many of our state’s country roads.

These nifty safety mechanisms help stop an out-of-control vehicle from leaving the road and colliding with objects, running down embankments, or rolling over.

“RAA welcomes the increased rollout of safety barriers on regional roads, as this is a cost-effective road safety treatment that is proven to save lives,” RAA Senior Manager of Safety and Infrastructure Charles M­ountain says.

While safety barriers don’t necessarily prevent all crashes from occurring, they can substantially reduce the severity and change the type of crash that occurs.”

What are safety barriers?

Road safety barriers come in various shapes and sizes and are made from materials like concrete, cables or steel. Each type has several benefits and disadvantages. Here are three that you might’ve seen on South Australian roads.

Flexible: More commonly known as ‘wire rope barriers’, these flexible safety barriers are made of several pre-tensioned cables designed to absorb the impact of a collision.

This type of barrier is most effective at reducing the impact of a crash and can be cheaper to maintain than the other options. They can also be loosened by emergency services when there’s an emergency and the barrier is in the way.

Unfortunately, flexible safety barriers can’t be installed on roads where there are tight curves or crests. Their high level of deflection in a collision also means they are less practical in constrained environments.

Semi-rigid: W-beam steel barriers, supported by a series of posts, are commonly seen along South Australian roads in both country and metro areas. They’re easy to install, versatile and able to be used on roads with tight corners. On popular motorcycling routes, the barrier installations often incorporate additional safety features to protect motorcyclists in the event of a collision.

Rigid: Concrete barriers are a better option for heavy vehicles and are only used when barrier deflection can’t be permitted. Instead, they absorb collisions without usually requiring replacement, but they are less forgiving than other barrier types – meaning that impacts can still be severe.

Where can safety barriers be placed?­

Safety barriers can be installed on both curved and straight sections of road even though crashes are more likely on curves.

Mr Mountain says run-off road crashes often occur on straight, flat roads despite curves presenting a higher risk.

“Roads with fixed unprotected roadside hazards such as trees, roadside ditches, power poles and rocks are more likely to score a low AusRAP star rating meaning it poses more of a risk to road users,” Mr Mountain says.

“Installing a safety barrier will reduce the risk and improves the star rating of the treated section of road.

“On average, each incremental increase in star rating reduces the risk of fatal or serious crashes occurring by 40%, so one to two stars is a 40% reduction, and one to three stars is a 64% reduction.”

Road barriers aren’t just placed on the side of roads. They can also be installed in the centre of the road to separate traffic travelling in opposing directions.

Can safety barriers stop head-on crashes?

Head-on crashes make up less than 5% of casualty crashes, but still account for almost a quarter of fatalities on regional roads.

To reduce the chances of head-on crashes, barriers have been installed at several high-risk locations including along Victor Harbor Rd at Willunga and on the Sturt Highway in the Barossa Valley.

“Safety barriers help stop vehicles from crossing onto the wrong side of the road,” Mr Mountain says.

“Wire-rope centre barriers almost entirely eliminate the risk of head-on crashes occurring.”