An unusual biannual spike in truck accidents on the Canterbury coast has been attributed to daylight savings.
The NZ Transport Agency data showed trucks crashed more in September and March, when daylight savings starts and finishes.
Since 2003, 80 trucks have rolled on the coast between Christchurch and Kaikoura.
Daylight savings starts next month.
NZTA transport officers manager Tony McNeill said: ''We are finding that up to 60 per cent of the crashes are happening in September/October and March/April. This is when we get the seasonal shift in freight coinciding with daylight savings.''
Sleep patterns are disrupted and neighbourhood barbecues, lawn mowing and outdoor activities impact on drivers' sleep, he said.
The biggest risk for truck drivers on the coastal route was between 3am and 6am, he said.
''The challenge is how to keep drivers safe on this return leg from Picton when fatigue is starting to set in and they are looking forward to the end of their shift,'' he said.
''As the statistics show, 78 per cent of rollovers happen at advisory corners and 80 per cent of the time the road is dry."
The draft Canterbury road safety action plan, by the Canterbury Regional Road Safety working group said trucks are ''disproportionately'' represented in crash data in Canterbury.
It said heavy vehicles make up up 3.4 per cent of vehicles in Canterbury but are involved in over 9 per cent of regional crashes.
The risk of truck crashes in urban streets had increased due to the rebuild, said the report.
''While it is necessary for these vehicles to be in residential and urban areas, it does pose an increased risk to other road users who may be less familiar with sharing the road with large vehicles," it said.
''Conversely, truck drivers using unfamiliar residential roads may be less familiar with sharing the road with cyclists, pedestrians and children."
Police say they are focusing on truck drivers next month and will breath test every person stopped and ticket all travelling over the speed limit by 5km or more.
- The Press
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