Snipping the ribbon on the first section of the Kapiti expressway is Transport Minister Simon Bridges, Te Ati Awa iwi member, Grace Ahern, 6, Otaki MP Nathan Guy, and iwi member Ruby-Mei Franklyn.

Wellington's proposed 110km expressway from the airport to Levin looks like it will end up being even longer, with the Transport Minister saying he is keen to extend it further north.

Simon Bridges expressed an appetite for expanding upon the already $2 billion-plus roading project on Thursday as he cut the ribbon to open the first section of the Kapiti expressway four months ahead of schedule.

The $630 million, 18km expressway from Mckays Crossing to Peka Peka on the Kapiti Coast is part of the Wellington Northern Corridor - one of seven Roads of National Significance being built across the country.

MARK COOTE The Mackays to Peka Peka section of the Kapiti expressway, from Poplar Ave, with a pedestrian over bridge.

The $850m Transmission Gully motorway being built north of Wellington and the proposed $330m second section of the Kapiti Expressway, from Peka Peka to Otaki, are also part of the corridor.

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Once those motorways are connected to several other major roading projects, motorists will enjoy a four-lane, expressway-style journey from Wellington's airport all the way to just north of Levin.

Joel Maxwell Former Transport Minister Gerry Brownlee turns the first earth on the Kapiti expressway in 2013.

But Bridges said there was scope to push the expressway further.

"I think the logic for going further is pretty strong actually."

It was more a case of when and how much, not necessarily if, he said.

JOEL MAXWELL/FAIRFAX NZ The road ahead - looking south down the first section of the Kapiti expressway, from the new bridge over the Waikanae River.

"Ultimately, really, it's more a question of timing and costing - all those things we'll work through."

Otaki MP Nathan Guy was also keen to push on.

"Extending these roading improvements further north is definitely worth looking at."

JOEL MAXWELL/FAIRFAX NZ The Kapiti expressway drew a string of protests and opposition from some in the community.

It made sense to start planning now for the population and business growth "that's already happening in Horowhenua" on the back of the $2b spend by the Government, he said.

On Friday NZ Transport Agency highway manager Neil Walker confirmed planning would start soon on future transport connections "between Palmerston North and Wellington".

Safety improvements had been made at Manakau and Ohau on SH1, and contracts awarded to replace the Whirokino Trestle and Manawatu River Bridge, north of Levin. Work would start "later this year", Walker said.

MARK COOTE The Mackays to Peka Peka section of the Kapiti expressway, from north of Poplar Ave.

Automobile Association spokesman Mike Noon said extending it should be looked at.

"What I would say is that taking it even north of Otaki is going to have a profound effect on Wellington, and opening up the city."

Ideally, New Zealand should have "a really good road" from Wellington to Auckland, he said.

JOEL MAXWELL/FAIRFAX NZ Looking north from the Waikanae River bridge on the Kapiti expressway, with a few vintage props set up on the road as part of the completion ceremony.

Palmerston North Mayor Grant Smith said extending the corridor made sense for the city with most of the lower North Island's freight either coming through Palmerston North or being generated in the region.

It made sense to at least connect up the section of SH1 between Foxton and Sanson with the corridor, he said.

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JOEL MAXWELL/FAIRFAX NZ Speaking at the official completion ceremony for the Mackays to Peka Peka section of the Kapiti expressway is Transport Minister Simon Bridges.

Ken Shirley, chief executive of the Road Transport Forum, which represents the freight trucking industry, said the next logical step would be to keep improving the corridor north, fix three dangerous "big dips" along the Desert Rd, and meet up with roading improvements in the Waikato.

"There's nothing more wasteful for trucks than being caught in traffic jams and gridlock like we've had on the Kapiti Coast."

'LITERALLY THE BEST ROAD IN NZ'

JOEL MAXWELL/FAIRFAX NZ The road north toward the Te Moana Rd overbridge on the first section of the Kapiti expressway.

Bridges said the completed section of the Kapiti Expressway "literally is now the best road in New Zealand".

It would improve journey times to Wellington's port, its CBD, the Interislander ferry terminal, the airport and hospital, benefiting the wider region.

More than $200m of the Mckays to Peka Peka expressway spend went into the Kapiti economy through local businesses, and more than 5000 people worked on the project, he said.

NZTA The Leinster Ave footbridge over the new Kapiti Expressway.

The expressway will not open to traffic until later this month but there is an open day on February 18, which will be a chance for people to experience the road beforehand.

BY THE NUMBERS

3,500,000 cubic metres of earth shifted - that's 102 rugby fields piled 5m high

1,400,000 new plants over 140 hectares

70,000 cubic metres of concrete poured - enough to lay a footpath from Wellington to Auckland

18 new bridges

16 kilometres of shared pathway for cyclists, walkers and, in most sections, horses

14 hectares of wetlands created