Water carts and chip spreaders are on standby as state highways heat up.

NZ Transport Agency Waka Kotahi is advising drivers to drive to the conditions.

"If the conditions change, reduce your speed. That also applies to these long, hot summer days," said an NZTA spokesperson.

With an increase in temperatures over the past few days, NZTA  is aware that some roads in the regions have shown signs of ‘bleeding seal’ or sticky surfaces.

The first onset of hot weather in a season can create issue with newly constructed chip seals especially on uphill inclines but settles down as we move through the summer. 

Even some older seals can “liven” up with the first flush of hot weather. Saturated road surfaces can sometimes also exacerbate ‘bleeding seal’ as water is released from the road.

NZTA Hawke’s Bay / Tairawhiti system manager Martin Colditz said road temperatures are typically significantly hotter than the air temperature on any given day, given the road surface retains the sun’s heat for a lot longer.

“For example, when the air temperature reaches the high 20’s or early 30s, the temperature of the road may reach 55 degrees Celsius or higher.

“Bleeding seal isn’t an East Coast-specific occurrence," Colditz said.

“NZTA currently has crews out actively monitoring the state highway network for signs of ‘bleeding.’

“Water carts are also on standby and being used to spray water at sites which have previously been known for bleeding. Spraying water helps the road cool and prevents bleeding in the first place."

Colditz said a  water cart and chip spreader have been used on previous occasions to successfully address bleeding seal.

“Our crews are also using trucks to spread sealing chip at sites which have already started bleeding. This has a number of benefits, including protecting the road surface and preventing soft bitumen from running off the road; and improves traction especially for heavy vehicles," Colditz said.

“If there is loose chip at sites, we’ll have warning signs in place reminding road users.

“The biggest thing road users can do to help avoid bleeding and minimise the disruption at sites which are already bleeding, is to drive to the conditions. If there are speed restrictions in place, please respect them. It’s crucial to follow the traffic management in place and the speed limits.

“By respecting those speed limits, we can prevent further damage at other sites, while also minimising the chance of crashes and possible injuries to people."

At a glance

What is being done about the sticky highway surfaces?

• Monitoring: NZTA crews are actively checking the state highways for signs of ‘bleeding.’
• Cooling: Water carts are on standby to spray water on hot spots, helping to cool the roads and prevent bleeding.
• Chip spreading: Crews are spreading sealing chips on affected areas to protect the road surface and improve traction.

What can you do?

• Drive to the conditions: If the road is sticky or there are speed restrictions, slow down and follow the traffic management signs.
• Respect speed limits: This helps to keep people safe, minimise damage to the roads and prevents further issues.
• Report issues: If you see bleeding seal or have safety concerns, call 0800 4 HIGHWAYS.

Plan ahead for a safe, enjoyable journey. Keep up to date with:

• Traffic updates: journeys.nzta.govt.nz/traffic
• Facebook: https://www.facebook.com/nztahbg
• X: https://x.com/nztacni
• Journey planner: journeys.nzta.govt.nz
• Phone: 0800 4 HIGHWAYS (0800 44 44 49)