The Transport Agency says it will look at the infrastructure of the entire transport corridor from Ngauranga to the Hutt Valley, extending a investigation which has already begun.
In June, the agency announced it would investigate a cycleway and pedestrian path between Ngauranga and Petone, north of Wellington.
However, after a storm in June when part of the seawall fell away, the agency has decided to expand the study to all forms of transport.
The corridor is used by trains, buses, freight, cars and cyclists.
The agency says it will consider how to better protect travellers from disruptions caused by natural disasters.
Investigation work is expected to be completed next year.