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My wife and I support and apply the "Dipped Headlights on" as a voluntary practice in NZ, not just in poor light but in all daylight conditions and wanted to know the breakdown of the accident risk reduction from doing this.

We feel that if oncoming drivers see us coming, then our safety chances have just taken a quantum leap!

We look forward to your answer as winter is upon us all!

Brian & Janet

From the "Ask Jack" archives -


Your email was forwarded to our Motoring Affairs team in Wellington for response.

The AA supports the use of lights on during the day under certain circumstances, although we do not support making them mandatory unlike some European countries and Canada. Essentially, our advice to motorists is to consider turning your headlights on in low light conditions during the day, especially during winter or when weather conditions are poor. Having your headlights on (dipped beam) is the best way to let other drivers know that you are there. If you have difficulty seeing other vehicles on the road, then those other drivers will have difficulty seeing you.

We have researched this issue thoroughly and there are several reasons to support voluntary use. In the 9 countries where daytime lights are mandatory, many cars have daytime running lights (DRL) which are separate to headlights and come on with the ignition but switch off when the headlights are turned on, and are not as bright as full beam so do not dazzle.

International evidence suggests mandatory DRL would reduce daytime crashes by 6-9%, however local studies suggest that such significant savings would not apply to NZ because of our brighter natural light (compared to low-light Northern Hemisphere countries where the evidence was sourced) and the fact that fewer accidents are attributed to poor visibility or lighting in NZ. In addition, new studies overseas show that DRL has led to an increase in accidents involving 'vulnerable' road users (cyclists and motorbikes). This is because cars or trucks with headlights on essentially makes bikes (travelling a little in front) invisible to oncoming traffic as their single beam is mistaken as one of the twin beams of the vehicle behind.

Recently, the NZ Transport Agency proposed making headlights mandatory on all motorcycles (it is common voluntary practice) in order to make them more visible against other traffic. The AA and various road safety groups support this proposal, which would be undermined by making DRL compulsory on all other vehicles.

To complicate things further, mandatory DRL is proven to increase fuel consumption by 1-2% (because more electricity needs to be generated by the engine to keep headlights running). If it were mandatory in NZ, this would equate to an extra 128 million litres of fuel consumed per year.

While safety is paramount, the cost of extra fuel consumed (plus the cost of modifying cars so lights come on automatically with the ignition) cannot be totally ignored,hence there are no proposals to make DRL mandatory in NZ (excepting motorbikes).