New Zealand state-owned rail operator KiwiRail has completed re-alignment of an unstable section of Main South Line (MSL) track in Dunedin that was damaged by severe storms in June.
The storms damaged a number of embankments on the MSL track with the big embankment at 365.85km becoming dangerously unstable.
As part of a remedial work, KiwiRail made a temporary re-alignment by cutting into the slope alongside the big embankment, and pulled the track off to remove immediate risk.
In addition, about 3,000 cubic metres of rock were stockpiled in a confined site ahead of time and then moved once reconstruction work was started.
KiwiRail senior engineering geologist Daniel Rodriguez said: "The big storm meant enough water had entered into the embankment to destabilise it. The solution was to remove the saturated embankment material and replace it with modern engineering fill.
"Replacing a six metre depth section of a 70 metre-long embankment with an operating railway running along the top is not easy, especially when you’ve only got a weekend to do the job in."
KiwiRail project engineer Robert Storm said: "The line is now better aligned and the slope is stabilised and this should improve its efficiency and safety for years ahead.
"So while the issue of not running trains at all was solved by the temporary alignment, it still needed improving as soon as possible and the opportunity for a weekend BOL in early December provided us with the ability to do that.
"We were able to remove and replace enough of the old embankment to bring the track back into its original alignment."
Image: MSL shunting yards in Dunedin. Photo: courtesy of Benchill.