When driving along Queensland's M1 motorway, it can be hard to tell where Brisbane ends and the Gold Coast begins.

Key points: 350,000 people are expected to move to the Gold Coast in the next 20 years, with northern suburbs likely to handle much of the growth

350,000 people are expected to move to the Gold Coast in the next 20 years, with northern suburbs likely to handle much of the growth Pimpama, situated along the M1 corridor, is the third-fastest-growing suburb in Australia

Pimpama, situated along the M1 corridor, is the third-fastest-growing suburb in Australia New residents are attracted to the Gold Coast for its lifestyle, but say traffic congestion is a major concern

With around 170,000 vehicles travelling between the two cities every day, congestion is increasing in the suburbs of Oxenford, Coomera, Upper Coomera, Pimpama and Ormeau.

Property developer Greg Rix remembers the area as a mix of trees and dirt roads in 2001.

"Twelve-thousand to 15,000 people move to the Gold Coast every year, and the northern corridor was the obvious location where these people had to go to live," he said.

"It hasn't abated — you've got to realise the northern corridor is still on fire."

Between 2011 and 2016, the area's population jumped 31 per cent to more than 74,000, but Mr Rix said infrastructure was struggling to keep pace.

"We are building ourselves out and we are strangling ourselves with infrastructure," he said.

"Roads, first and foremost, need paramount attention."

The M1 is the crucial transport link between Brisbane and the Gold Coast. ( ABC Gold Coast: Dominic Cansdale )

Dealing with growing pains

Mr Rix said the number of new registered homes in Pimpama reached 1,500 in 2017, with around 4,700 people — average age 27 — moving to the suburb.

"It's a huge rental market [and there are] first home buyers, which means new residents for the Gold Coast."

But with most employment opportunities found outside these suburbs, and with 88 per cent of journeys on the Gold Coast made by private car, the demographic shift presents a headache.

Paul Coupeland, who has lived in Ormeau for 18 years, said he now found transport increasingly problematic.

Paul Coupeland has lived in Ormeau for 18 years. ( ABC Gold Coast: Julie Clift )

"Basically, the amount of traffic and the constant getting on and off [the freeway] into the suburb, probably all the way down the coast now, has become fairly difficult," he said.

"It's a very busy road now, and of course they don't seem to come up with any alternative."

Local residents remember

When Heather Jay began working at Yatala Pies in 1981, it was a "suburban bakery" just off the highway, serving commuters halfway between Brisbane and the Gold Coast.

"The M1 is nowhere near a suburban road anymore, so that's the biggest change, just the pure population," she said.

"All the suburbs are just so much bigger."

Heather Jay says increased traffic along the motorway has changed the area. ( ABC Gold Coast: Julie Clift )

The iconic pie shop cradles the City of Gold Coast's northern suburbs, which Ms Jay said now made up a big part of her business.

"They're little satellite cities ... things are changing so quickly," she said.

"You'd hope to see less commuters because a lot of people can use modern technologies to work from home."

The growing population has helped sales at Nathan Said's business in Pimpama. ( ABC Gold Coast: Julie Clift )

When homewares store manager Nathan Said moved to Pimpama eight years ago, it was "just cane fields and bush".

"We were told it was going to be a growth area, but we always just thought, 'Nah, they're just saying that'," he said.

"We never thought it would become like this."

With Pimpama's population now at an estimated 16,000 — up from about 9,000 in 2016 — "the traffic can get a bit full-on", Mr Said said, adding that the area needed to "move with the times".

"I think we need a police station around here; that's probably the number-one thing, and probably a post office."

Around 200,000 vehicles use the M1 between Brisbane and the Gold Coast each day. ( Supplied: Jessamie Jackson )

In defence of development

Builders and developers were often blamed for congested roads and stretched infrastructure, Mr Rix said.

"The development industry turned the areas of Coomera, Upper Coomera, Pimpama, Ormeau into thriving communities," he said.

"We supplied the infrastructure — that means sewerage, roads."

Greg Rix was one of the first people to establish large-scale developments in Pimpama. ( ABC Gold Coast: Julie Clift )

But he said there was "a lag in police, ambulance, fire brigade" services usually provided through the State Government.

"The developer pays $28,500 in infrastructure charges for every new lot he opens, the developer pays GST on land sales, the developer pays land tax.

"The developer is upfront funding bureaucracy, [so] don't blame the developer.

"The northern corridor is screaming for more infrastructure."

What's the future?

With the state election due in October 2020, congestion has become a critical issue for both major parties.

The Government has committed $120 million to build three new train stations on the Gold Coast, including one at Pimpama, while it and the LNP have both promised to duplicate sections of the M1.

Consultation is underway for duplicating the motorway between Nerang and Coomera, a road used by more than 210,000 vehicles a day in early 2019.

Mr Rix said predictions that Brisbane and the Gold Coast would merge into "one corridor of constant development" were now a reality, with the northern suburbs set to reach capacity.

"Pimpama was supposed to be built out by around 2035; that's not going to happen, it'll be built out probably before 2030," he said.

"You're going to see 40,000-plus residents in each of those areas ... it's going to be its own community."

In the Australia Talks national survey, 61 per cent of respondents identified population growth as a problem.

The ABC asked 54,000 Australians about their lives and what keeps them up at night — use our interactive tool to see the results and how their answers compare with yours.

Visit ABC iview to watch a special TV event in which some of Australia's best-loved celebrities explore the key findings of the survey.