Police are still investigating why two cars collided head-on, killing five people near Te Awamutu last night, and say one car crossed the centreline but excessive speed was not a factor.
However, Waikato police roading manager Inspector Jeff Penno said the speed limit on the three-lane stretch of road, which featured a northbound passing lane and single southbound lane, might be too fast.
On Wednesday, Penno told a media conference the highway had a 100km/h speed limit, but international evidence showed where a road was undivided, as was the case on that stretch of SH3, a speed limit of 80km/h was safer and survivable.
The road where the crash happened, a few minutes north of Te Awamutu, was not high-risk, he said.
"We know as a police district we put the most vehicles down the highest risk roads in the country, which is why we are infamous for our road trauma. This piece of road is not one of those roads."
Two occupants in one car and three in the other died at the scene and Penno described the crash as tragic.
"This is a horrendous event and our hearts certainly go to the friends and family of those that are starting a long journey of pain and suffering."
The crash involved two cars that collided when one crossed the centreline just before 4.45pm, Penno said.
The initial investigation showed the road did not contribute to the crash but it carried a higher risk because it was undivided by barriers, though it featured a painted median strip, he said.
Both vehicles were older model cars and it was unclear whether all the occupants were restrained by seatbelts, Penno said.
While excess speed did not appear to be a factor, police could not rule out other possible causes.
"Impairment is always something we look at, so to ensure all drivers are sober and not just alcohol but legal and illegal drugs, and that is certainly a focus of this accident."
The question now was whether the road's speed limit was appropriate, he said.
Residents' difficulty getting onto road from driveway
A resident not far from the crash scene, Margaret Alexander, was at home when she heard a small bang and went to her kitchen window.
"The car that had crashed was sideways on it's side, on the northbound lane and you couldn't see. And then the fire engines arrived and they just put a big cover over the car which we thought wasn't a good [sign]."
Alexander and her husband, Dane, had lived on the highway for 55 years and said this was the only crash on the three-lane stretch of road which had ended in tragedy.
The pensioners said they sometimes had difficulty getting in and out of their driveway because of the volume of traffic and speed.
That was because they had to cross two northbound lanes to go south at the same time southbound motorists were coming off another passing lane.
Margaret said often those cars were going as fast as possible to overtake before the passing lane ended.
However, she believed the road was safe and other residents said they did not think the 100km/h speed limit needed to be reduced.
Waipa Mayor Susan O'Regan said the sadness of loss of life on this scale had a ripple effect in the community.
"Even though we don't know the identity of who was sadly killed in the accident, it certainly is having a big impact on Te Awamutu in particular."
The crash was the second fatal in four days on Ōhaupō Rd after former Waipa councillor Jim Parlane died further up the state highway on Friday.
NZTA says it brought in safety measures seven years ago
New Zealand Transport Agency (NZTA) maintenance and operations regional manager Roger Brady said seven years ago it introduced a range of safety improvements on the road including side barriers.
"In 2017 a range of safety improvements were implemented on SH3 between Ōhaupō and Te Awamutu, including 10km of side barriers, 33km line marking, right turn bays, slip lanes and roadside hazard protection.
"The wide centre-line and roadside wire safety barriers can reduce death and serious injuries."
The crash was not in an identified high-risk area and NZTA was assisting police with the investigatio, he said.
"We will also carry out our own review of the crash site, as we do in response to all fatal crashes on the state highway network, with a focus on the potential contribution of any road or roadside factors to the crash, and any safety improvements which can be made at the site.
"It's important that allow this work to be completed in order to have a full and accurate understanding of all of the factors which may have contributed to this crash."
Friday's fatal between Airport and Kaipaki roads was 8.2km away from last night's crash, which was between Jary and Ngaroto roads, Brady said.
"NZTA doesn't have any current works on this stretch of SH3 and no planned upgrades to the area."
NZTA's programme of work for infrastructure improvements was prioritised according to risk, Brady said.
"This includes the crash history of different sections of state highway, traffic volumes, and the potential for reducing deaths and serious injuries.
"We have an obligation to invest in safety improvements where they are most needed and have the greatest impact."
He said the agency's thoughts were with the whānau, community and everyone affected by the tragedy.
NZTA is assisting the Police Serious Crash Unit, which is leading the investigation into last night's crash.