State Highway One near Ohakea was closed for most of Sunday after a double road fatality and a major chemical spill.
The Lower Hutt driver of a tanker, 48, was killed after swerving to avoid a pedestrian on SH1 at about 6am, but was not able to miss him.
The pedestrian, a Feilding man, 21, was killed.
The tanker then skidded and rolled about 50 metres.
SH1 at Ohakea was closed from about 6am until 7pm on Sunday as police worked with contractors to clear the tanker which was carrying 16,200 litres of caustic soda when it crashed into a ditch.
Police say approximately 12,000 litres of the chemical leaked into the ditch and the edge of the field.
They say the remaining caustic soda was pumped from the crashed vehicle to another tanker.
Police say the drainage ditch had to be pumped out and then citric acid and sand put on the area to neutralise the caustic soda.
They say next week the area contaminated by the caustic soda will need to be dug out.
Police say the recovery operation was very complex with the use of three cranes and the fire service.
They say a number of trees lying between the crashed tanker and a field had to be felled to provide clear access to the vehicle.
Police are investigating why the 21-year-old man was walking along SH1 and whether he is linked to a crashed car found in nearby Wilson Road.