The Rail Accident Investigation Branch (RAIB) – one of the bodies looking into the Stonehaven Derailment – has published an update on the passenger train derailment that occurred on 12 August in Aberdeenshire.
The six-car train derailed at 9:38am after hitting a landslip roughly 2.25km north-east of Carmont. In total, the train was carrying 9 people, of whom three were staff. The driver, the conductor and one passenger died in the accident. The remaining individuals were taken to hospital.
On the morning of 12 August the region experienced thunderstorms associated with heavy rainfall. Around 52mm of rain fell in the Carmont area over a four-hour period preceding the accident. For context, that is nearly 75 percent of the total monthly rainfall (70mm) for an average August in Aberdeenshire.
The accident site is on the double track main line between Dundee and Aberdeen. The train operating company responsible for the service was Abellio (as ScotRail). The train in question was an HST with a leading power car, four Mark 3 passenger coaches and a rear power car. It was operating as train reporting number 1T08, departing Aberdeen for Glasgow Queen Street at 6:38am.
The stop following Aberdeen was Stonehaven, which it departed on time. The train travelled past Carmont on the southbound line until the signaller at Carmont stopped it via radio message at 6:59am. The signaller had received a report from the driver of train 2B13 on the northbound line that there was a landslip obstructing the southbound line between Carmont and Laurencekirk.
As a result of this, train 1T08 was stationary south of Carmont for more than two hours. Shortly after 9am the rain stopped and the weather was sunny by 9:30am.
The 2B13 northbound train that originally reported the landslip had been held at Stonehaven station because of reports of flooding between Stonehaven and Aberdeen. At 9:10am, after its passengers had alighted, train 2B13 was moved forward by a short distance to make room on the platform at Stonehaven.
Train 1T08 could not continue its journey south so it was decided that it was to return to Stonehaven to allow its passengers to make alternative arrangements for onward travel. At 9:25am train 1T08 received permission to begin moving north and was routed over a crossover at Carmont on to the northbound line. The signaller at Carmont cleared the signal for the train to carry on to Stonehaven. After passing the crossover at 5mph, the driver came close to the set linespeed of 75mph – the maximum permitted speed for HSTs on this stretch of line – after roughly 1.4 miles.
At 9:38am the train hit a landslip covering the northbound line, whereupon it derailed. The track curved to the right, whereas the train continued travelling straight for approximately 70 metres until it hit a section of bridge parapet, which was destroyed. The leading power car continued almost all the way over the bridge and fell off the line down a wooded embankment, as did the third Mark 3 coach. The first passenger coach came to a stop on its roof, having rotated to be almost perpendicular to the track. The second passenger coach also overturned on to its roof and came to a stop on top of the first coach. The fourth passenger coach remained upright and attached to the rear power car. It too came to a stop on the first carriage. All of the wheelsets of the rear power car derailed but it remained upright.
On the left-hand side of the railway line (in direction of travel) a steep slope rises to a field that then slopes more gently away from the railway. There is a drain that runs northwards along the lower edge of the field until it reaches an access chamber roughly 50m to the south of the landslip area, from where it runs diagonally down the steep slope, passing through two further access chambers. It then reaches an outfall structure at a track-level ditch, which takes water northwards towards Carron Water. The drain running diagonally is made up of a 450mm diameter plastic pipe at the bottom of a trench. Following the installation of the drain, the trench was filled with gravel. Water flowing from land above the railway washed some of this gravel on to the railway line, along with some larger chunks of rock.
The Rail Accident Investigation Branch is currently gathering evidence so that it can identify the relevant factors behind the accident. It will likely examine the following areas:
The RAIB will publish its findings, including recommendations, once it concludes the investigation.
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