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.