On 21 October 2024, a passenger train heading westwards from Shrewsbury to Aberystwyth on the Cambrian Line in Wales collided head-on with another train heading in the opposite direction on a section of single line approximately 900 m (1⁄2 mile) west of the passing loop at Talerddig, Powys.

Most of the route is single track, with passing loops provided at strategic points to allow crossings of trains in opposite directions.

[2] Talerddig was a station and passing loop at the summit of the Cambrian Line between Caersws and Machynlleth.

The station opened in 1900 and was closed in 1965, but the passing loop remained in use and is a regular crossing point for trains.

From this level stretch, the line descends at a gradient of 1 in 56 (1.79%), steepening to 1 in 52 (1.92%) after the first mile down to the former Llanbrynmair station.

Unbraked goods trains always had assistance at the rear if not also at the front, because of the danger that a broken coupling could result in a runaway wagon.

[11] Before the impact, the driver of the Shrewsbury to Aberystwyth train had entered the saloon to warn passengers of the impending collision.

[23] As a result of the accident, plans to close the A470 between 31 October and Christmas were postponed, with the work rescheduled to take place early in 2025.

[24] As a direct result of the accident, Transport for Wales cancelled four services on the Cambrian Line until further notice.

[27] The RAIB's initial inspection of the track found evidence of low wheel/rail adhesion, and they stated that the possibility the train may have suffered wheel slide while braking would be investigated.

[11][28] A Rail Head Treatment Train had visited the line four times in the previous five days, including the night before the accident.