Down to the wire

Picture yourself driving a typical New Zealand highway with the last trace of summer in the air.

You notice a car in the opposite lane drifting left towards the edge of the road. Suddenly it pulls back hard to the right, veers towards the centreline and straight at you.

Does the road have a median barrier? In the time it took you to read that seven-word question the answer will have shaped the future of not just the people in the vehicles, but their families and friends.

If the road has a barrier, the other vehicle hits it and – while it will be a terrifying moment – you are physically untouched. Even the people in the car which hits the barrier are likely to survive.

If the road doesn’t have a barrier and the vehicles collide at high speed, the impact will be like falling from a high rise building. Sometimes people are lucky and only suffer minor injuries, but death or severe injuries are the most likely outcome.

“We sometimes get contacted by Members saying if people drove properly then we wouldn’t need barriers,” AA Motoring Affairs General Manager Mike Noon says. “In a perfect world that would work, but we know that things are never going to be perfect. Even if we managed to get every single reckless, drunk and drugged driver off the roads forever, you are still going to have people suffering medical events, vehicle failures, and drivers making mistakes or nodding off.

“Barriers are like emergency parachutes when you’re skydiving. Hopefully you never need them but if you ever do, it can save your life.”

The numbers speak for themselves

The AA looked at data for eight stretches of highway around the country with median and side barriers, like the new expressways in Kāpiti, Tauranga and Waikato, as well as older roads like the coastal highway on SH1 north of Wellington and SH58 between the Hutt Valley and Porirua.

In two years from 2017-2018, the barriers on those roads were struck at least 159 times and needed repairing. That is 159 times a potential head-on crash could not happen because barriers were in place. Over that period there was just one fatal crash across all those divided highways and that crash involved a vehicle hitting a pedestrian walking on an expressway.

The figures are just as compelling looking at before-and-after crash comparisons on stretches of highway that have had median barriers added. The road between Hutt Valley and Porirua has had a 95% reduction in fatal and serious crashes and SH1 north of Wellington an 88% reduction,
thanks to barriers going in 15 years ago. In just five years, the median-divided SH1 in Rangiriri, Waikato, experienced 65% fewer such accidents.

Fergus Tate is one of New Zealand’s leading road safety experts and has no doubt that New Zealand could and should be adding more barriers to its roads. The Technical Director of Transport for engineering firm WSP says that while adding rumble strips, widening road shoulders and improving line markings do make a difference, adding median barriers delivers the greatest crash reductions.

“Once a road is carrying more than 6000 vehicles per day, head-on crashes are the greatest risk of deaths and serious injuries,” he says. “The bulk of head-on crashes do not involve overtaking, either. The most common situation is people crossing the centreline on a bend; people going off the road to the left then over-correcting and ending up on the wrong side of the road is very common as well.

“Once something like that happens, it’s just luck as to whether another vehicle is coming the other way.”

People often have doubts about the value of barriers on the side of roads, but over 40% of fatal crashes involve a single vehicle going off the road, commonly crashing into a power-pole, tree or ditch.

International experience

New Zealand currently has in the vicinity of 400km of median-divided highways across the country (mainly motorways and expressways); the Government aims to have about 700km by 2021. That will be a big increase but we will still have significantly fewer divided highways than many other countries.

One of the world’s road safety leaders, Sweden, turned many of its undivided two-lane highways into ‘2+1’ roads. These highways are three lanes wide with a median barrier that alternates to provide passing opportunities. Vehicles might drive for 5km with two lanes on their side of the barrier before it switches and becomes a single lane for 5km before switching back to two.

Sweden and New Zealand have a similar-sized road network but Sweden has more than 5000km of divided highways. If New Zealand had half the amount of divided highway that Sweden has, it would equate to median barriers along SH1 from Cape Rēinga to Bluff, as well as east-to-west from New Plymouth to Gisborne.

Since 2016 the Australian state of Victoria has been on a mission to install more than 2600km of wire-rope barriers by the end of 2020. Fatal and serious crash numbers have nearly halved on the 19 roads that have been upgraded.

“Road safety always has a number of factors involved, but the AA certainly sees the much greater number of divided highways as a big part of the reason why Sweden and Victoria have half the rate of road deaths that New Zealand does,” Mike Noon says.

What’s the hold up?

It’s undeniable that barriers reduce the harm from crashes and make roads safer, so why not just put them on every highway across the country straight away?

Like everything in road safety, there are trade-offs and limitations in the real-world around cost, suitability in different locations and public acceptance. Fergus Tate has seen barrier installation projects cancelled because of opposition by residents and others concerned about not being able to turn right or pass slower vehicles.

There is also a balancing act on costs. If a median barrier can be added without increasing a road’s current width, the cost would be about $750,000 per kilometre. If the road has to be widened, costs can jump to between $2 million and $5 million per kilometre.

In terms of a pure bang-for-buck approach, we could add many more barriers if we put them in without changing anything else on a road but, from the AA’s perspective, a more balanced approach is needed.

“If people know that they aren’t going to have to wait too long for a safe passing opportunity or a place to pull off the road, they’re more likely to support barriers being installed.

“Barriers save lives and New Zealand needs more divided highways but we also need to be smart about where we put them and how we do it,” Mike Noon says.