Highway meltdown arrives early this year in ‘extreme weather’
The sweltering summer heat is melting roads across New Zealand.
Following a week of blistering temperatures, some road surfaces have reached 60 degrees Celsius, causing the bitumen to ‘‘bleed’’.
Two state highways have started melting in Marlborough, often crowned the sunshine capital, but softer roads have also been reported in Canterbury, Wairarapa and Manawatu¯ .
NZTA transport system manager Frank Porter said it was unusual to see the bitumen melt at this time of year.
Porter said there had been melted bitumen on the route between Blenheim and Nelson and also in Marlborough’s Wairau Valley, along the alternate highway to Christchurch.
‘‘We’ve had some areas where the bitumen has started bleeding on State Highway 6, and State Highway 63 [in Marlborough] was particularly bad towards the end of last week.
‘‘It’s not so common this early in the summer, [but] the last week’s run of weather has been quite extreme,’’ Porter said.
Bitumen bleed happened when bitumen below the chip seal melted and rose to the road surface, which increased the risk of skidding.
‘‘Motorists need to be aware the roads could be slightly slippier and there’s not that hard chip right up on the surface so when motorists see that black seal they should travel around the corners slower, they should increase their travelling distance behind another vehicle.’’
NZTA had added new chip on some segments of the melted roads in Marlborough, with signs showing where there was bitumen bleed.
‘‘On both of those roads we’ve made a significant effort to try and correct those areas, we’ve laid new chip, where we actually preheat some of the chip and when the road surface is very warm, we add the preheated chip and the new chip will embed into the sticky bitumen,’’ Porter said.
NZTA journey manager Lee Wright said if motorists got bitumen on their vehicle, baby oil and kerosene would help clean the bitumen off paintwork.
‘‘A newly surfaced road may take a little longer to settle in the very hot weather and people may encounter loose road chip and see bitumen tracking along the road. It is important to slow down at these sites and follow any temporary speed advisory signs,’’ Wright said.
Marlborough woman Sally McLennan said on social media the tar on her street was ‘‘liquid’’ by 9am.
‘‘And it was only resealed a couple of months ago. It’s a bloody mess.’’
Renee Roberts said her 5-yearold son had discovered it was ‘‘great fun to get hands sticky and covered in it too’’.
But Aidan McClure, who lives in Melbourne, Australia, said he could not understand why roads in New Zealand were melting. ‘‘In Australia, it never happens – not even when temperatures are in the
mid-40s. Surely it’s a matter of construction method?’’
Porter said chip seal was commonly used in New Zealand because it was less expensive than other surfaces. ‘‘There are other surfaces but they’re a lot more expensive and not affordable and you start getting into asphalt surfacing which doesn’t flush up the way chip surfaces do.’’