The ongoing investigation into last month’s fatal train crash, which sadly left one person dead and four more seriously injured, appears to be focusing on the emergency braking system on one of the trains.

The Rail Accident Investigation Branch (RAIB), which is trying to find out what led to a collision between two trains near Telerddig, has provided an update this morning.

The accident caused the line via Newtown and Welshpool to close for a week and rail users are advised to check before travelling, as further disruptions are possible in the coming weeks.

Here is the full statement from RAİB:

On: At around 19:26 on Monday 21 October 2024, train 1J25, a 18:31 Transport for Wales passenger service from Shrewsbury to Aberystwyth, collided with train 1S71, a 19:09 Machynlleth to Shrewsbury passenger service, also operated by Transport for Wales. .

The collision occurred approximately 900 meters west of the bypass loop on Network Rail’s Cambrian line at Talerddig, Powys. One passenger died and four people were seriously injured. Eleven more people suffered injuries requiring hospital treatment.

Neither train was derailed in the collision, but the leading vehicles of both trains suffered serious damage.

RAİB was informed at 19.45 on the night of the accident and a team of inspectors was immediately dispatched to the scene. Over the next few days the RAIB worked with British Transport Police, the Rail and Road Agency and relevant railway companies to secure the evidence necessary to support our independent safety investigation.

RAIB notified Network Rail of the accident scene on Wednesday evening, 23 October 2024, for inspection and repair of the line and recovery of the trains. Both trains were removed from the site on Friday, October 25, 2024. RAIB investigators and support staff continued to collect evidence at the crash site and nearby locations until Saturday, October 26, 2024.

Both trains involved in the accident were 2-car class 158 diesel multiple units. These units are equipped with wheel slip protection systems, functionally similar to anti-lock braking systems on road vehicles, and an automatic sanding system that automatically discharges sand via sanding hoses when wheel slip is detected during braking. The purpose of this is to increase the available friction at the wheel/rail interface.

The Cambrian line is equipped with the European Rail Traffic Management System, a type of railway signaling. This system eliminates the need for trackside signals by transmitting signaling and control data directly to the train. The boundaries of each section of road controlled by the system are indicated by reflective line edge markings known as block markings.

The railway approaching Talerddig from all directions consists of a single line. A loop is provided there to allow trains to pass each other. There are points at each end of this that allow trains to enter a short length of track adjacent to a single track. Westbound trains climb a rising grade to enter the loop and on the way out rejoin the single track as it descends towards Llanbrynmair and Machynlleth.

RAIB’s preliminary investigation revealed that westbound train 1J25 had to stop at the loop at Talerddig to allow eastbound train 1S71 to pass. Initial analysis of data from the on-train data recorder (OTDR) fitted to train 1J25 shows that the driver applied the service brake to slow the train as it approached the loop at Talerddig. Approximately 40 seconds after the first service brake application, the OTDR records that an emergency brake request has been made. This emergency braking request remained in place until the collision. OTDR data shows that wheel slip begins during service braking and is constant during emergency braking.

Train 1J25 then entered the loop at Talerddig. Although the train slowed down as it went through the loop, it did not stop before passing the block marker located near the exit. The train then exited the loop, rejoined the single track and continued traveling down the descending grade for approximately 900 meters before colliding with train 1S71.

There is conflicting evidence regarding the speed of the trains at the time of the collision. Initial analysis showed that train 1J25 was traveling at a speed between 24 km/h (15 mph) and 39 km/h (24 mph), while train 1S71 was traveling in the opposite direction at around 10 km/h (6 mph). hours) shows that it is traveling at speed. The RAIB continues to analyze evidence relating to collision speed, which remains an area of ​​ongoing investigation.

Following the accident, RAIB carried out measurements of wheel/rail adhesion levels at various locations from the approach to the Talerddig loop to the point of impact. These found low levels of wheel/rail adhesion.

An examination of the automatic sanding system installed on train 1J25 after the accident showed that the sanding hoses on the lead vehicle of this train (which were active at the time of the accident) were clogged and apparently unable to discharge sand.

Our investigation will attempt to determine the sequence of events leading up to the accident.

It will also take into account:

• The actions of those involved and the factors that may have influenced them
• Current level of wheel/rail adhesion from approaching the talerddig cycle to the point of impact
• Condition and performance of braking, wheel slip protection and grinding systems on train 1J25
• behavior of both trains during and after the collision
• Transport for Wales’ policies on low wheel/rail adhesion and how the risk of low adhesion on the Cambrian line is managed
• Network Rail’s policies on low wheel/rail adhesion and how they manage the risk of low adhesion on the Cambrian line
• Processes used to assess and control the risk of flooding in the Cambrian line
• Key factors involved, including actions taken in response to previous relevant security recommendations.