Thousands are expected to take part in Sunday's Round the Bays in Wellington. File photo. Photo: Supplied
People taking part in Round the Bays in Wellington on Sunday will need to navigate traffic congestion.
Passenger services on the Hutt Valley, Kāpiti, Johnsonville and Wairarapa lines will be replaced by buses.
Several bus routes through Kilbirnie will also be detoured.
KiwiRail said the closures were necessary for pre-planned maintenance and further inspections of overhead power cables - which saw trains suspended last month.
Greater Wellington transport chair Thomas Nash said Metlink would be providing additional buses to replace trains.
"Metlink, Transdev and KiwiRail are in the unenviable position of having to balance the extremely pressing need for renewals and maintenance on our ageing rail network against keeping services running for significant events like Round the Bays," Nash said.
"I've asked Metlink to report to the [transport] committee on what we can do to improve services around major events, and on the cost of providing unimpeded, peak level connections for events that meet a certain threshold, such as All Blacks tests and concerts at Sky Stadium."
Round the Bays Wellington, now in its 46th year, is the largest mass participation event in the lower North Island and the third-largest in New Zealand.
The first runners to start - those undertaking the half marathon distance - will set off from Waitangi Park at 7.45am, with festivities kicking off at the end-point at Kilbirnie Park from 8.30am.
Wellington City Council has listed numerous road closures around the city at various times between 5am - 1pm on Sunday as a result of Round the Bays.