A towbar was completely ripped out of a vehicle when the trailer it was towing was hit by an oncoming ute on the Rimutaka Hill on Saturday.
The crash happened at 12.40pm, about a kilometre down from the summit of the State Highway 2 Rimutaka Hill Rd on the Featherston side.
Masterton traffic Sergeant Chris Megaw said a 55-year-old man from Porirua had been driving his work vehicle, a white ute, northbound down the hill.
"He goes around a right-hand curve and he starts drifting over into the oncoming lane."
Another man, 56, from Wainuiomata, driving a grey work ute and towing a trailer, was travelling southbound up the hill.
"The man towing the trailer sees the ute drifting into his lane and he pulls over to the left to get out of the way.
"But there is very little shoulder and the bank is right there and he can't get over far enough to get out of the way," Mr Megaw said.
The ute coming down the hill crashed into the trailer.
Mr Megaw said when the trailer was hit the towbar was ripped clean out of the back of the grey ute.
Nobody was injured in the crash.
Featherston Fire Brigade was called to help with traffic control and cleaning up the site.
Mr Megaw said one lane was closed off for about an hour.
The white ute had extensive damage to the steering and was towed, as was the trailer. The grey ute was able to be driven.