'Bro, I'm awake now'

A truckie allegedly fell asleep and rolled his truck, blocking three lanes, then walked out and told police officers, "bro, I'm awake now".

It was one of a series of crashes on slick Waikato roads this morning that have seen one person seriously hurt. Police are warning motorists to stay alert and drive to the conditions.

The Mainfreight truck blocked three lanes on the Lichfield stretch of State Highway 1 in the South Waikato and had since been cleared, police said. No other vehicles were involved.

Tokoroa Senior Sergeant Graeme Hill said the crash happened about 4.30am and police were shocked to see the man walk away from the crash.

"He walked out and said, 'bro I'm awake now'," Hill said.

"He fell asleep behind the wheel, and he didn't sustain any injuries."

The road was blocked for three hours but was now open.

Hill said it was a timely reminder for drivers not to test their limits on the road.

Meanwhile, Waikato shift supervisor Senior Sergeant Peter Simpson warned motorists to keep their wits about them in the wet weather, saying areas of road where oil had built up over the long dry period would be greasy and dangerous.

At 4.29am police were called to a single-vehicle crash on SH1 south of Huntly where the driver lost control in slippery conditions.

The person was taken to Waikato Hospital with serious injuries.