The speed limit on an unforgiving stretch of highway has now dropped to 80km/h, despite intense community opposition.
Motorists will now have to drive slower on a long stretch of the road between Napier and Taupō - in a bid to make the road safer, after several fatal accidents.
Waka Kotahi, the transport agency, calls the move crucial - but it has not been popular with regional leaders.
Nine people died between 2019 and 2020, but no one has died on the road since October 2020.
Those driving along the road on Friday had mixed opinions.
Sophie from Crownthorpe said it was "slower than normal".
She often went to Taupō, as her family had a bach there.
"I've got two kids under three, so this is the first time I'd actually had to stop, because they were getting real angsty about how slow it was."
Emily from Havelock North said the road desperately needed an upgrade.
"I've been behind trucks and cars, so it hasn't felt particularly slower than usual, but the road is in a really poor condition. It'd be nice to see a little bit of improvement in the roads, I've actually had damaged tyres on this road before."
Robyn, who was driving from Matamata to Dannevirke, said the speed change was a good idea "because there have been too many accidents".
"It's not the road, it's the drivers, that's what I think," she said.
However, Taupō Mayor David Trewavas said people would get "so frustrated".
"It's going to be a frightening thing, it's going to add to the time of travel."
Sergeant Paul Ormerod was patrolling the road on Friday and said driver behaviour had been "pretty good".
"Generally, people are sticking around the 80 to 90-92 k mark, the odd car has been creeping over 100 and we've stopped a few cars this morning. We haven't issued any tickets today, but we have helped educate people on the change in speed limits."
His advice was to use cruise control on the road.
"That'll really help you keep that speed, you will creep up more going downhill when you're at 80k's, and you just won't notice it because you're used to travelling at 100. Be a bit more focused. Trucks are probably more congested because they can go now the speed limit so they're kind of driving a bit more like cars and overtaking on passing lanes which isn't the norm."
Hawke's Bay leaders are still unhappy with the decision.
The region's transport committee chairman Martin Williams wrote to Transport Minister Michael Wood earlier this week.
"First and foremost the principal request is an opportunity to meet with the minister at mayoral level, involving the mayors of the territorial authorities whose districts absolutely hinge in terms of well-being on the lifeline which that corridor provides," he said.
He said a judicial review was still possible.
"We're getting, with urgency, legal advice on that, as we resolved to do as a regional transport committee two or three weeks ago.''
He said there was a "very significant disappointment for many people in the region and "their voices haven't been heard".
Waka Kotahi regional relationships manager for the central North Island Linda Stewart said the agency would complete an evaluation of the speed change in 12 months.
"[It] will consider the safety, economic and social impacts of the 80km/h speed limit being introduced on 76km of this 122km section of SH5 between Napier and Taupō," she said in a statement.
"Safe and appropriate speed limits are just one part of a larger programme of work to make State Highway 5 safer for everyone who uses it. Waka Kotahi is also looking at investments in safety improvements, such as shoulder widening, wide centrelines, side barriers and some intersection improvements, as well as the annual maintenance programme to repair and renew the highway."
Furthermore, it was developing a business case for a long-term improvement strategy along the road.
