B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
B61L23/00—Control, warning or like safety means along the route or between vehicles or trains
B61L23/08—Control, warning or like safety means along the route or between vehicles or trains for controlling traffic in one direction only
B61L23/12—Control, warning or like safety means along the route or between vehicles or trains for controlling traffic in one direction only partly operated by train