Rail Accident Investigation Branch says verified pre-accident inspections had found no track defects in the area.
Network Rail said the height and rural location made the repair a 'complex' job.
Three men died when a ScotRail train struck a landslip following heavy rainfall on August 12.
UK transport secretary Grant Shapps made the comparison when the rail tragedy was raised in the Commons.
Network Rail interim report published into crash that killed three people in August.
Investigators are finding it difficult to access the site where three people were killed after a train derailed in Stonehaven.
Police investigating after jogger spots damage to main entrance door at popular Stonehaven tourist attraction
The Ship Inn in Stonehaven, Aberdeenshire, was targeted during the early hours of Saturday morning.
Around 200 pupils from Dunnottar Primary School in Aberdeenshire have been told not to come in.
Residents in Malcolm's Way in Stonehaven have raised thousands for charity over the years.