Opinon: Looking back at Abermule 1921 - a head-on collision on Cambrian single line that killed 17

Abermule lies 17 miles east of Talerddig, the site of October 21’s runaway and head-on collision.

There’s little railway at Abermule today, just a level crossing. But in 1921 there was a station, signal box, goods yard and passing loop.

Abermule sits in history as the site of one of the railway’s worst head-on collisions, on January 26 1921, in which 17 people died.

Inspecting Officer J W Pringle delivered his report and recommendations to the Ministry of Transport ten weeks later (so a little more quickly than the year that most Rail Accident Investigation Branch reports take today).

The Cambrian Railway worked its single line with electric tokens. Machines at each passing loop held tokens for the sections on either side. Taking a token from one machine locked its twin at the other end of the single-track section. This meant that only one token could ever be out at a time.

Drivers had to check they had the correct token before proceeding. When they reached the other end of the single-track section, they would surrender the token to be placed back into its machine before another could be issued.

When January 21 1921’s westbound train arrived at Abermule, its driver gave up his Montgomery-Abermule token. There, he should have waited for the eastbound service, which was heading his way with a Newtown-Abermule token.

But staff at the station became confused by poor communication, and there was little supervision of the token machines (housed in the station building, not the signal box).

Staff thought incorrectly that the eastbound train was late, so there was time for the train now standing at Abermule to reach Newtown.

Relief-stationmaster Lewis instructed signalman Jones to clear his signals, and Lewis handed the driver the token which booking clerk Thompson had given him.

This was the same token the driver had given up. No one checked the token machines, otherwise they would have seen that a Newton-Abermule token had already been withdrawn, preventing them from doing so.

Nor did the westbound driver check that he’d been given the right token. Thus, he proceeded onto the single line with the wrong token, and met the eastbound express with calamitous consequences.

In his report, Pringle recommended interlocking between token machines and starting signals, such that the signal cannot be cleared unless the token is correctly taken from its machine.

But he fell short of recommending it for all single lines, noting “the high degree of security attainable when due regard is paid to regulations for single line working”.

In other words, Abermule’s accident would not have happened if staff had followed the rules. That’s still relevant today, but we’d also accept that people do make mistakes, and that interlocking provides a defence against that.