The UK's highest railway is set to be shut for safety reasons until at least November.

The Scottish Government economic development agency Highlands and Islands Enterprise took the decision to withdraw the beleaguered Cairngorm funicular railway from service on August 25 while a series of 'snagging' works were carried out.

It was supposed to be back in action at the start of September after it was hoped the works would be completed "relatively quickly".

But on September 6, it emerged that it would not be back up and running until the end of the month.

The agency later said the scale and complexity of the project, which includes continuous testing to ensure public safety, had led it to revise its schedule to complete the job to mid-October.

READ MORE: Scot gov agency sues creators of shut Cairngorm railway for £14.5m

Now HIE says the works to resolve the issues will have to continue into November and has apologised to visitors.

The decision to close the railway came after the leading Scottish Government economic development agency settled a court action against constructors and designers over structural problems. HIE said two weeks ago that it had received £11m after settling the court action.

It had been pursuing a £14.5m claim against the company that owns Morrisons Construction and the civil and structural engineers for the scheme.

The agency made claims over defects in the design and construction of the railway and breaches of contracts which emerged after the funicular was forced to shut five years ago.

The Herald:

HIE had at one point included a provision of £14.3m for the cost of reinstating the funicular which had been expected to take two years.

It finally came back into action in January after a four-year hiatus and following a two-year programme of works to strengthen the viaduct that supports the railway track.

HIE said a 12-month snagging and inspection programme has been running since the relaunch, "as is usual practice with complex engineering projects".

The latest disruption came following an inspection that showed that some of the ‘scarf joint assemblies’ that link the beams at the top of the piers did not meet the required tension.

An HIE spokesman said “Achieving resolution of the tensioning issue has proven more difficult and time-consuming than we had anticipated at the outset. At the same time, though, there can be no short cuts when passenger safety is concerned.

“We apologise to Cairngorm visitors for having to withdraw the service while these works are carried out.

“We are now looking forward to completing the project during November when the operators of Cairngorm Mountain will also be carrying out their annual maintenance programme.

The Herald: Skiiers and Snow boarders at the Ptarmigan summit at the Cairngorm ski area, Aviemore.....Photograph By Colin Mearns.  15 February 2005..Stock Photograph..

“Every effort will be made to reintroduce the service in good time for the start of the 2023/24 snowsports season at Cairngorm.”

The Cairngorms is a major Scottish tourism attraction and centre for recreation with downhill hillwalking and rock climbing a major draw for the 1.92m who visit the national park every year from around the world.

The crucial funicular, which was opened in 2001 and connects a base station with a restaurant and a ski area 1,097m (3,599ft) up Cairn Gorm mountain near Aviemore, was closed in September 2018 due to structural issues.

News of the long-running case emerged in 2021 when it was revealed that ministers had to refund part of an EU grant for the original Cairngorm funicular because of discrepancies in the way it tendered for the work as costs spiralled.

As of the end of last year the cost to the taxpayer of funicular had soared to nearly £52m - with the costs of crucial repairs spiralling.

The cost of the repairs rose by 56% from £16.16m to £25m.

The faults were discovered after the costs of building the funicular spiralled from £14.8m to £26.75m.

Calls were made for a public inquiry into the management of the Cairngorm funicular, which it was hoped would re-open in late 2022.

A £14.5m claim was made against the now owners of Morrison Construction, Galliford Try Infrastructure Limited and Inverness-based AF Cruden Associates Limited, the civil and structural engineers for the scheme which had been taken over by Glasgow-based Arch Henderson.

The case was due to be dealt with in a proof hearing at the beginning of August.

But HIE confirmed that it had reached an out-of-court settlement for £11m - £3.5m less than the original claim.

HIE said that while the works continue, Cairngorm Mountain remains open.

It said that the funicular is a "unique and complex structure", comprising a mostly single track and a short loop section where upward and downward trains can pass one another.

The 1.7km viaduct is supported by 94 piers of varying heights, each one effectively a small bridge.

It ascends 450 metres up Cairn Gorm, with the track entering a 300m tunnel in its final stage leading into the top station.

The agency said: "Technical challenges involved in the current works are compounded by the mountain location, where access can prove difficult and weather and temperature conditions are prone to sudden and dramatic change."