The proposed shared cycle and pedestrian walkway running between Petone and Ngauranga Gorge.

A $35 million seaside path linking Wellington and the Hutt Valley has been confirmed.

The NZ Transport Agency announced on Friday it had plumped for the more expensive seaside route for a cycle and pedestrian pathway to finally unite the valley and the city, and siphon cyclists off the busy highway.

Consent applications were expected to be lodged next year and the agency would look to start construction on the pathway in 2019 at the latest.

Wellington Cycling Action Network spokesman Patrick Morgan said the decision was a long time coming, with calls for a cycleway mentioned in Hansard records from 1905.

"This ticks all the boxes, it's going to be a great tourism asset, it's going to ease traffic congestion and make parking easier in Wellington."

He said the pathway would boost cycle safety by drawing riders away from the highway.

"Most people can't travel between the Hutt and Wellington by bike, because they don't want to mix with State Highway 2 traffic."

After public consultation the agency picked the seaside route over the cheaper option of a roadside path, which would have cost between $16m and $22m.

The new path would be three metres wide, with a 1m shoulder on either side, between the railway lines and a newly extended seawall.

Agency spokesman Anthony Frith said the path would link with The Esplanade at its Petone end and join the existing cycling and walking network to Seaview.

"Heading north from Petone, pedestrians and cyclists will travel along the new path to connect with Petone station via an overbridge."

From Ngauranga the path would connect with the existing path, "although there are proposals to upgrade this section also through to Wellington railway station".

The cash for the project would mostly come from the national land transport fund, Frith said, but how costs would be shared with the Hutt, Wellington and regional council was "yet to be finalised".

In a rare moment of motorist and cyclist unity, the Automobile Association's motoring affairs general manager Mike Noon said the announcement was "very good news".

"It's extremely good news because the current route is inadequate and forcing people to ride on the road, which is a much higher risk."

Agency central regional director Raewyn Bleakley said the preferred option would act as a buffer against events such as the 2013 storm that saw waves crashing onto the railway and highway, "contributing to massive disruption", she said.

Frith said the extended seawall would prevent debris being blown inland from the sea and would be designed to "minimise sea spray and, where possible, to withstand environmental effects".

"It will be well maintained to ensure it is kept clear of any hazards for cyclists. The result will be a far safer route for cyclists, and a more resilient rail and road corridor."

Wellington Mayor Celia Wade-Brown said the seaward pick was a good decision and would provide a 20-minute commute for cyclists on a flat route between the two cities.