From RAIB at https://www.gov.uk/government/news/freight-train-derailment-east-somerset-junction
At around 17:50 hrs on Monday 20 March, six loaded wagons of an eastbound freight train became derailed as the train passed over East Somerset Junction, between Castle Cary and Frome, while travelling at about 20 mph (32 km/h). The train, the 17:05 hrs service from Merehead to Acton yard, was joining the up Westbury line from the Merehead single branch line.
There were no injuries. The accident resulted in substantial damage to the railway infrastructure; around 100 metres of track including two sets of switches and crossings were destroyed. Train services between London Paddington and the West Country were diverted via Swindon while the wagons were recovered and track repairs took place over the following four days.
The freight train consisted of a class 59 diesel-electric locomotive hauling 38 loaded wagons of types JNA, JHA, HOA and IIA. It was carrying stone from the Merehead quarries for use in the construction industry. The wagons that derailed were the 24th to 29th from the front of the train. The train split between the 21st and 22nd wagons when the derailment occurred, and the train was stopped by the automatic application of the brakes.
The leading wagon which derailed was of the HOA type. The derailment occurred close to where a set of trailing points had been removed and replaced by plain line in 2012.
Our investigation will identify the sequence of events that led to the accident, and how the wagons derailed. It will also include consideration of:
* the condition of the track, its geometry and how it was maintained
* how the wagons were loaded
* the condition of the wagons
* any relevant underlying management factors
Our investigation is independent of any investigation by the railway industry, the British Transport Police or by the industry’s regulator, the Office of Rail and Road.
We will publish our findings, including any recommendations to improve safety, at the conclusion of our investigation. This report will be available on our website.