People heading back into Auckland have faced massive delays on the roads - with one woman reporting a nearly 10-hour crawl from Taupō.

Many other families have reported spending several hours sitting in traffic trying to get through Auckland's Covid-19 checkpoints, after the city went into alert level 3 lockdown early yesterday morning.

Another long day of queues is expected today - with police and road authorities urging people to "please be patient".

But people are confused about the need for checkpoints for those trying to get into the city.

At Mercer, a queue that was more than a kilometre long earlier this morning, quickly diminished to about 500-metres just after 8am.

However, a steady flow of traffic continues to come through.

State Highway 1 is split into two lanes - one for cars and one for trucks, which is relatively free-flowing.

Between 7.30 and 8am, it looked as though two cars were turned away.

Police officers and Defence staff are lined up the off-ramp at Mercer where people are being asked what their reason for travel is and if they have documents for proof of travel.

Senior Sergeant Jonathon Chappell, speaking to Newstalk ZB at the Mercer checkpoint, said 23,000 vehicles had been through the five checkpoints on Auckland's southern border since the start of the lockdown.

In 22 hours, only 320 vehicles had been turned back for either not having a legitimate reason for travelling or not having the required paperwork.

Most people had been understanding, though Chappell said "you can't please everyone".

One man tried to get through with an exemption he was given in August, was turned around, tried to come back later, and was turned around again.

He then came back later came back and had actually altered his exemption form to make it look current. Unfortunately for him, he pulled up to the same official who recognised him and turned him around again.

ACT leader David Seymour wrote on Twitter: "The Government needs to explain why it is blocking people going into Auckland. People are reporting six-hour waits and ambulances rescuing distressed motorists."

Speaking to Newstalk ZB this morning, he described the fiasco as "absolutely extraordinary".

"It just beggars belief. I mean, I had people texting me all night - we had people, in their nineties, having to go to the bathroom on the side of the road, ambulances collecting people because they'd expired in the heat.

"And it shows a few things - first of all, this government's total lack of commonsense. Why would you stop people entering Auckland?

"The point is to keep the virus contained within Auckland, not stop people going home."

Seymour said he could not understand how government officials failed to anticipate the thousands of people who would be trying to head back home to Auckland over the weekend.

"Even if you do want to stop people entering the area, given the extraordinary circumstances of calling restrictions with no notice in the middle of the weekend, of course there are going to be thousands of people trying to re-enter Auckland on Sunday night.

"How the Government failed to anticipate that and created a kind of disaster it did, I'll never understand."

Prime Minister Jacinda Ardern this morning told Newstalk ZB's Mike Hosking that what we saw happen yesterday was the effect of a lockdown taking place in the middle of a weekend.

Defence Force called in to help

Additional staff from the NZ Defence Force have been drafted in to help ease queues, she said.

"MBIE here have done an incredible job. Yes, the first level 3 was tough and we needed to improve at the border.

"Now we have a regime where everyone is just reissued their documents so they are able to move straight away."

Waka Kotahi NZ Transport Agency issued an alert on Twitter early today reminding motorists of checkpoints at State Highway 1 and SH2.

"Travel to (and) from Auckland is restricted at Covid level 3 with journeys for essential purposes only.

"Please be patient with delays expected a police checkpoints at SH1 Te Hana, SH1 Mercer & SH2 Mangatāwhiri."

Police said traffic at some of the checkpoints remained heavy at times overnight and that they hoped to release figures relating to the first day of checkpoints later today.

Motorists who contacted the Herald yesterday reported having to sit in long queues for anything between two to nine hours.

One woman, who did not want to be named, said she had been in traffic south of the city for six hours.

She left Rotorua at 1pm and still hadn't reached the Auckland southern border checkpoint by 10pm.

"I have not gone above 5km, I have crawled."

The woman said people were getting out of their cars and running to a nearby gas station to get food and then making it back to the car before it had moved very far.

People were also dashing from their cars into the bushes on the side of the road to go to the bathroom, she said.

"It seems crazy it's taken us so long to get back in. I don't blame the police at all. I just hope they could do something slightly different."

She had food and water but wasn't drinking it - out of fear she might need to go to the bathroom.

Auckland resident Olivia Savidan drove back to the city from Raglan and said she covered about 7km of motorway in five hours.

She was travelling back after a "mums and daughters" trip away with seven mothers and nine daughters, but the usually two-hour commute had taken the group more than seven hours.

"We're joking about how lucky and fortunate we are we don't have a crying baby or a pet," Savidan said.

"The girls are staying entertained. Everyone is going to the toilet on the side of road, it's not exactly graceful.

"We can't believe there is a border control coming back into [Auckland], we'd expect it going out. This is just crazy."

But not even the lengthy traffic delays could wipe the smiles off the daughters' faces after their weekend away, with the young girls all in good moods after hours stuck in traffic.

"One of our girls did burpees on the side of the road.

Another mum in the group, Nerolie Curran, was upbeat about the traffic delays.

"We're just playing our small part for New Zealand to keep us as open as we can."

She said she'd wait in the queue again "any day".

"The only reason we could go away with a group of friends is because New Zealand has done so well to get this far. This is just part of making sure we can do more weekends away."

Other motorists also reported lengthy delays heading back into the city, with one woman saying she'd been in the car for almost 10 hours as she drove back to Auckland from Taupō.

The trip usually takes just over three hours.

Shorter wait north of Auckland

Meanwhile, a Northland man said he got through the northern border in about 20 minutes, most other motorists are experiencing delays of several hours - up to six hours by 6pm today in at least one case.

One man heading from Hamilton to Auckland was stuck in the northern checkpoint for nearly four hours, while another motorist has seen people "toileting" on the road side and heard cries from babies.

By late afternoon, police had set up a dedicated "livestock lane" to help expedite the travel of vehicles transporting animals.

Those who had stock or animals and were stuck in traffic were urged to call *555.

text by Belinda Feek and Vaimoana Tapaleao