Armi Tunnel Stall

How the poor quality of coal and overloading of a train led to it stalling in the Armi Tunnel.

With rail tracks on steep gradients, including inside tunnels, the amount of spare power can sometimes not be enough. On March 2nd, 1944 a heavy freight train was further loaded by the 600 passengers on board. The coal used was also of very poor quality, being very dusty, reducing the power available.

As the train reached the Armi Tunnel, the steam pressure was dropping, the wheels began to slip, and the train came to a stop in the tunnel with the back end still out in the open. Carbon monoxide fumes and smoke filled the tunnel, resulting in over 400 fatalities.

The excessive expectations and failure to provide adequate resources amounted to a safety-critical system used outside its operational envelope.


A less serious consequence was the result of the Channel Tunnel fire.