The New Zealand Transport Agency has drafted a series of options as part of a road-safety push by Associate Transport Minister Julie Anne Genter.
Based on crash data from the last decade, there have been around 650 head-on collisions each year, 12 percent of which were fatal.
On average, 90 people are killed in head-on collisions annually and a further 320 are seriously injured.
However, installing median barriers could reduce the number of these deadly or serious injury crashes by 90 percent. These options range in cost and coverage from hundreds of millions to almost $2 billion.
Cost: $368 million
Road Coverage: 246km
This would have prevented 27 of the deadly or serious injury crashes (DSI) that occured in 2017, and reduced the severity of 63 crashes.
NZTA says these 'Quick Win' roads have a benefit cost ratio (BCR) of 1.64 or 1.55 based on 2017 data.
A BCR greater than one means the benefits of having median barriers on these roads will outweigh the costs of installing them because of medical costs avoided due to fewer crashes.
To be classified as a 'Quick Win', roads must be 10 metres wide with fewer than two intersections and two driveways per kilometre.
There must also be a history of high rate head-on collisions, including at least three deadly or serious crashes in the past five years.
This would have prevented 49 DSI crashes in 2017, and reduced the severity of 97 crashes.
This option includes 'Quick Win' roads with a BCR lower than one. However, this option still has a BCR of 1.11, or 1.43 based on 2017 data.
This would have prevented16 DSI crashes in 2017, and reduced the severity of 32 more.
These are the roads that don't fit the definition of a 'Quick Win', however the benefit of having median barriers on these roads will still outweigh the cost of installing them.
These roads have a BCR of 1.32, or 1.3 based on 2017 data.
This would have prevented 45 DSI crashes in 2017, and reduced the severity of 123 crashes.
This includes roads deemed 'Other Opportunities', so don't fit the definition of being 'Quick Win' roads, where median barriers would help reduce the road toll.
However, due to the need for major road works like widening, straightening or other safety improvements the BCR of these roads is 0.66, or 0.74 based on 2017 data.
Cost: $1.98 billion
This would have prevented 94 DSI crashes in 2017, and reduced the severity of a further 220 crashes.
This combines options two and four and has a BCR of 0.82, or 0.99 if using 2017 figures.
Watch the video for the full story from John-Michael Swannix.
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