Each passing loop is controlled by a small signal box, known as a block-post. These house the lever frames that control the points, the token equipment and telephones. The railway has few signals; instead it has stop boards at Pendre, Brynglas, Quarry Siding and Nant Gwernol, and the blockman allows trains to proceed by use of flags. There are colour light signals located at Tywyn Wharf, operated from the Control Office and disc signals controlled from the ground frame. Abergynolwyn has colour light signals, which are operated from the blockpost. When the block-post is unmanned, it is the responsibility of the locomotive crew to change the token before proceeding.