Vehicle warrant of fitness inspectors alarmed at illegal repairs of seatbelts have forced action from authorities.
The NZTA has received a number of calls and complaints about the north Canterbury off-ramp.
About a third of all fatal crashes in New Zealand involve someone under the influence of alcohol or drug.
Police are particularly interested in hearing from any truck drivers in the area at the time.
"There's lots going on and people might be feeling anxious."
"Free lesson: Load trailers correctly and use an appropriate towing vehicle."
Road diversions are still in place in the area.
An investigation is underway into a pile-up between a truck and three cars.
The crash involved one truck and three cars.