Special trains due to clear the leaf mulch that caused last year's double train crash near Salisbury had been delayed, an interim report has found.

The Rail Accident Investigation Branch (RAIB) has published the findings of its own investigation, suggesting leaves crushed by passing trains had contributed to low friction between the train wheels and the tracks.

Strong winds and heavy rain also played a part.

Thirteen people were taken to hospital after a South Western Railway (SWR) service collided with a train from Great Western Railway (GWR) just outside Fisherton Tunnel on October 31 last year.

Both trains, carrying around 200 passengers, derailed and slid into the tunnel. 

The driver of the SWR service, 74-year-old Robin Tandy, suffered life-changing injuries after getting trapped in the cab. He was released by firefighters.

The report's findings

Shortly after the incident, which caused the line to close for about two weeks, RAIB investigators attended the scene.

Their interim report contains details of the crash and the weather conditions at the time of the incident.

Key findings mention low adhesion as a likely cause. This was due to the railhead being "contaminated" by "black deposit".

The report states: "This deposit consisted of leaf material which had been crushed under the wheels of passing trains and which is often associated with low adhesion conditions.

"Analysis showed that many areas had a medium or heavy level of contamination, and that the thickness of the leaf deposit was relatively consistent through each of the areas surveyed."

The SWR service from London Waterloo to Honiton was travelling "within the permitted speed" and the signalling system was operating "as designed", investigators found.

However, water jetting to clean the tracks had been delayed that day due to planned engineering work between Southampton and Brockenhurst.

This meant that the tracks had not been treated for 32 hours instead of the usual 24.

A final report is due to be published at the end of RAIB's investigation.

You can read the interim report in full here.

Get more Salisbury news. 

You can also like our Facebook page and follow us on Twitter and Instagram to stay up to date, as well as signing up for one of our newsletters.

If you want online news with fewer ads, unlimited access and reader rewards - plus a chance to support our local journalism - find out more about registering or a digital subscription.

Email newsdesk@salisburyjournal.co.uk with your comments, pictures, letters and news stories.