Four faults were detected in a safety system for a train involved in a fatal crash, investigators have said.

Tudor Evans, 66, died and four others were seriously injured when two Transport for Wales (TfW) trains collided near Llanbrynmair in Powys on 21 October.

The trains were travelling in opposite directions on a single line and were meant to pass on an extra section of line, called the Talerddig Loop.

But the braking system failed on the westbound train heading to Aberystwyth and it skidded past the loop, colliding with the eastbound train from Machynlleth.

The Rail Accident Investigation Branch’s (RAIB) interim report into the cause of the crash revealed the trains collided at a closing speed of about 30mph (48 km/h).

Previously, the RAIB said an automated system that helped train wheels grip tracks had failed.

It said it had inspected the system fitted to the train heading to Aberystwyth which automatically sprays sand via hoses when a wheel slide is detected during braking in a bid to generate more friction.

Wednesday’s report revealed safety checks on the train braking system were not carried out because the driver was unable to do so as the train was parked next to a platform.

“Early on the morning of 21 October, a train driver prepared the train for service, however the train was positioned adjacent to a platform,” the report said.

“This meant that the driver did not have access to equipment on the train’s underframe, including the sander test button.

“Consequently, certain safety systems, including the operation of the automatic sanding system, could not be checked.”

The hoses fitted to the TfW train to discharge sand when wheels slide during braking were “blocked” with leaves and debris from trees, the RAIB said.

The investigators said: “This fault would have prevented sand from being ejected from the hoses.”

Two plates which measure the flow rate of sand were incorrectly installed, with both upside down and one misaligned.

Two electrical faults were also discovered.

A “basic check” of the system was carried out the day before the crash which “suggests that the sand hoses were not blocked at this time”, the report stated.

The reported highlighted other factors which could have contributed to the collision, including:

• Weather conditions – Storm Ashley had brought heavy rain three days previously
• Time of year – falling leaves on the line affected adhesion of the wheels on the track
• Adhesion improving gel was not used on the line

The RAIB’s investigation continues and a final report will be published at a later date.