The railway is single track, so special measures have to be taken to prevent collisions. Before preservation, the railway operated a "one engine in steam" policy, but with growing passenger numbers it became necessary to install passing loops and a more stringent method of single line control was introduced. The line is worked by Electric Key tokens, which authorise the driver to enter a section of single line, and these are interlocked to prevent more than one token being withdrawn for a section at any one time. There is a loop at Pendre, which was used from the opening of the railway for shunting purposes, and further loops were installed at Brynglas in 1953 and Quarry Siding in 1963. When the Nant Gwernol extension opened in 1976, Abergynolwyn also became a passing loop.