Highland train derailment was caused by signalling system fault
Get the Ross-shire Journal sent to your inbox every week and swipe through an exact replica of the day's newspaper
A signalling system fault was to blame for a train being derailed at Dalwhinnie, a preliminary investigation has found.
The empty high speed train (HST) was being used to check platform-train stepping distances when the accident happened in the early hours of April 10.
The Rail Accident Investigation Branch has said the train was wrongly diverted from the up line to the down line at a crossover located around 190 metres south of Dalwhinnie train station.
Before the train was able to be stopped, its rear three bogies became derailed due to the points at the north end of the crossover moving under the rear of the HST.
There were five staff members on the train but no-one was injured in the accident which happened at 3.03am.
The line had to be closed in the Dalwhinnie area causing six days of disruption for rail travellers with bus replacement services operating between the strath and Pitlochry.
The report states: "The crossover comprised a set of points at each end of a short section of track linking the up and down lines.
"The maximum permitted speed is 70 mph (113 km/h) on the up line and 15 mph (24 km/h) when traversing the crossover.
"The train was travelling at around 33 mph (53 km/h) when it was wrongly diverted onto the crossover and came to a stop around 290 metres beyond it.
"There were five people on the train including the driver. No one was injured. The derailed portion of the train, track and signalling equipment were damaged.
"The signal on the approach to the crossover was displaying a proceed indication for the route along the up line and there is no signalled route from there, over the crossover, to the down line.
"Both sets of points forming the crossover were detected as being in the correct position for the up-line route by the signalling system and were indicated as such to the signaller, even though the points at the north end of the crossover – the end nearest Dalwhinnie station – were set in a position to divert the train onto the crossover."
The RAIB investigation will now seek to identify the sequence of events which led to the accident.
Their probe will also consider:
* Why the signalling system did not detect that the points were in an incorrect position thereby allowing the signal to be cleared for the movement along the up line.
* How the points were able to move as the train passed over.
* Factors associated with the installation, testing and maintenance of the point machines that operated the crossover.
The RAIB investigation is independent of any probe by the railway industry or by the industry’s regulator which is the Office of Rail and Road.
Related: Derailment on Highland line