Turoa's High Noon Express rebuild complete
A major makeover for Turoa's High Noon Express has been completed in time for the 2011 snow season.
The rebuild, proposed by Doppelmayr who built the lift in 2007, is aimed at reducing problems caused by ice and wind in the chairlift's extreme weather environment.
Four extra towers have been installed, two existing towers relocated and several others were lowered. As a consequence, the High Flyer chairlift can no longer operate because the High Noon cable is now too low where it previously went over the top of the High Flyer bull wheel.
Ruapehu Alpine Lifts managing director Dave Mazey said the company had been in discussion with Doppelmayr for the past two years, looking at ways to reduce the problems they have faced in operating the lift.
He said that when the state-of-the-art six-seater detachable chairlift was built, the thinking world-wide was to have fewer towers, with bigger rope spans.
"It meant less holes in the ground, less visual impact, less cultural impact, less de-icing and servicing and less economic impact," said Mr Mazey.
He compares the 1.4km lift, with 11 towers, with Whakapapa's 20-year old Waterfall Express lift, with 17 towers over 1km.
But Turoa's unique environment - one of the toughest in the world for ski areas - has proved extremely difficult.
Mr Mazey said there have been around 100 derails of the cable in storms since it was completed.
In June last year, Tower 9 collapsed at the end of a storm cycle, after a natural ice release led to the cable whipping. The forces involved toppled the 18m high tower. Later in the same season, the top of Tower 8 was damaged in similar circumstances.
The ski area is known as the worst in the world for ice storms.
Mr Mazey said Doppelmayr's engineers believe that with the height of the towers, the length of the cable spans, the extreme winds on the south side of Mt Ruapehu - especially cross winds - all coupled with massive ice build up had compounded to set up "some sort of harmonic" that led to the derailing and damage.
He said the derailing was not just a case of the cable falling off the towers - sometimes it whipped up and down a huge amount, even flicking up above the top of the towers.
"Doppelmayr engineers (who have built lifts all around the world) have never seen it before."
After the tower collapses last year, Doppelmayr agreed that the modifications they were working through were not enough and came up with the proposal that has now been carried out.
Tower 8 is reduced from 19m to 11m, towers 1,2,9 and 10 are the same, while the rest are reduced in height by 3-5 metres.
Lowering the towers is designed to reduce the effects of extreme winds, especially across the lift line. Doppelmayr and RAL believe that the extreme wind effect is exponentially worse higher up the towers.
New towers - 7a, 8a, 9a - have been built near the top of the line, Tower 3 is moved about 20m down the slope and Tower 4 moved 44m up the slope and another new tower built in between.
More towers have combination sheave assemblies fitted - with wheels underneath and on top of the cable, to hold it in place.
Mr Mazey said the benefits from the modifications to the lift line will be that there should be much fewer derails and de-icing will be completed more easily and quickly. This should lead to the lift being operational sooner in he morning after storm events.
"We should see a quantum shift in the way we can manage this lift," said Mr Mazey.
"It's still a brilliant lift. All these issues are not about when it's running."
Ruapehu Snow Bulletin June 2011