A final report into the Stonehaven rail crash last year that killed three people will not be ready until 2022.
In August 2020 a landslip caused a ScotRail train to leave the tracks at Carmont, just south of the Aberdeenshire town.
An interim report, published by the Rail Accident Investigation Branch (RAIB) in April 2021 said a signaller was not aware of any obstruction on the line.
It also found that part of a key drainage system close to the scene was not inspected for eight years.
According to BBC Scotland, the final report, which had been expected this autumn, will not be published until January.
Driver Brett McCullough, conductor Donald Dinnie and passenger Christopher Stuchbury died when the 06:38 Aberdeen to Glasgow Queen Street train derailed last year.
The train had turned back to Stonehaven due to another landslip that had been signalled by a train driver travelling north from Montrose. Rainwater had overwhelmed a drain at the side of the track at Carmont and washed gravel onto the line.
The interim report found that the train was travelling at 72.8mph, the normal range for the line, which the driver was told was safe to do.
The report from RAIB is thought to be in its last stages.