Train derailment that led to major fire in South Wales caused by faulty brakes, investigators say

A train derailment which lead to a major fire in South Wales was due to a fault with the brakes on one of its carriages, investigators have said.

The diesel-carrying freight train, which was travelling at around 30mph (48kph) at the time, crashed as it travelled through Llangennech, near Llanelli on 26 August.

Ten of the wagons came off the tracks, spilling 330,000 litres of fuel, after the brakes became applied "at some point on the journey", the Rail Accident Investigation Branch (RAIB) said.

Police declared a major incident and 300 people were forced to leave their homes.

All the train's wheels were "probably rotating freely" when it left Robeston oil refinery in Milford Haven, the RAIB said after a preliminary examination, but "at some point during the journey" the brakes on the third wagon became applied.

This created a flat spot on some of the wheels, leading to a section of track being distorted and the subsequent derailment of the third wagon, followed by another nine.

The locomotive and the first two wagons came to a stop about 180 metres away.

The driver, who was unhurt, "looked back and saw that a fire had started in the wreckage", the RAIB said.

He uncoupled the locomotive from the first wagon and drove it around 400 metres away.

It was feared the diesel spillage into the nearby River Loughor could ruin the local cockle fishery industry, with the Food Standards Agency advising the closure of shellfish beds in the area's estuary.

The RAIB said its investigation will consider why the brakes on the third wagon became applied, the maintenance history of the wagon, whether any other factors contributed to the derailment and how it led to the fuel spillage and fire.

The train, owned by DB Cargo UK, was travelling to a fuel distribution terminal in Theale, Berkshire.