The boss of the $850 million Transmission Gully project worked on one of Queensland's biggest motorway jobs before shifting here.
Australian Mick O'Dwyer, Leighton HEB joint venture project director of design and construction, worked on the A$1.95 billion ($2.1 billion) Dinmore to Goodna Ipswich motorway upgrade.
He is now overseeing dozens of people, fine-tuning plans for the 27km four-lane alternative route between Cannons Creek northwest of the Hutt Valley and MacKays Crossing south of Paraparaumu.
"Dinmore to Goodna was the biggest project I've worked on. In 2010, Goodna was under 30ft (9m) of water," he said, recalling challenges of that huge motorway project which was an 8km upgrade of the Ipswich Motorway, which started in mid-2009 and officially opened in 2012.
Transmission Gully is the Sydney-born O'Dwyer's first New Zealand job but he has worked overseas before, including in Belgium, and now lives in Mt Victoria, Wellington.
Transmission Gully is due to open in April 2020 when O'Dwyer's role will finish: "I'm just design and construction," he said, referring to the much longer-term programme for The Wellington Gateway Partnership to then operate the motorway.
O'Dwyer said the Wellington work was difficult on many fronts.
"It's quite a challenge from an engineering perspective. There are fault lines - one that I'm aware of at Wainui - but it wouldn't matter where you chose the route north of Wellington, you would always find fault lines.
"But the biggest engineering demand is that it has to be resilient in an earthquake."
Initial site works will start around the physical middle of the project and that work will involve building cross culverts, stream diversions and preparing for major earthworks toward the end of the year.
Site offices will be located at the project's northern end where about 30 people will work, in the central area where up to 100 will work and south, for another 30 people.
Transmission Gully
•The Wellington Gateway Partnership to build and operate the motorway.
•Parties are Leighton Contractors, HEB Construction, ACC and InfraRed.
•First NZ motorway project procured through public private partnership.
•27km four-lane motorway to open to traffic from 2020.