Kiwirail has geotechnical engineers on-site today to investigate subsidence on a section of the Western rail line near New Lynn station in Auckland.

Passenger trains are running at a reduced timetable, and only a single track will be operational as a precaution from today, and there's no time frame for a fix yet.

Passengers heading West, towards Swanson, will have to transfer at New Lynn Auckland Transport says it is working closely with KiwiRail to minimise disruption.

 Kiwirail's Chief Operating Officer - Capital Projects & Asset Development - David Gordon spoke to Michael Cropp.