Wellington metro prepares for summer heat

KiwiRail’s Wellington Metro track team has been busy preparing the rail network for summer, carrying out maintenance designed to reduce the risk of track problems during periods of high temperatures. 

“With talk of a hotter than usual summer, we’ve been testing, lifting and clipping down sections of the Upper Hutt and Kāpiti lines that are more susceptible to buckling in very hot conditions,” says General Manager Wellington Metro Andy Lyon. 

“Doing this work before the hottest weather arrives helps make the track more resilient and reduces the likelihood of heat-related speed restrictions and disruption for passengers.” 

Steel rails naturally expand as they heat up and contract as they cool. This can create pressure within the rail and increase the risk of the track moving or buckling. 

Where testing shows the rail needs adjustment, KiwiRail can carry out a process known as de-stressing. This involves adjusting the rail so it is set at the right level of tension to better accommodate changes in temperature. 

The work is also part of KiwiRail’s wider approach to prepare the rail network for more extreme weather and the impacts of a changing climate. 

While it is too early to know whether heat-related speed restrictions will be needed this summer, KiwiRail will continue to monitor rail temperatures and weather conditions. Restrictions will be introduced where necessary to keep trains operating safely. 

“Our focus is on addressing the underlying causes of heat-related track instability by ensuring the rail is correctly stressed and that the track, sleepers and ballast are in good condition,” says Mr Lyon. 

The Wairarapa Line in particular has benefited from significant track renewal work in recent years, making it less susceptible to heat-related track movement than some other parts of the Wellington network.