1996 – Nov – Lechowicz – Radar Based Level Crossing Control

Steve Lechowicz Principal Software Engineer Teknis Electronics Current level crossing control systems use either conductive or voice frequency track circuits. Both of these methods require physical connection to the track and rail-wheel contact. The first involves cutting the track which is inherently dangerous and costly to maintain. The second is so tuned to the electrical characteristics of the track that it is intolerant of such environmental variables as dew or rust. Voice frequency circuits are also susceptible to electrical interference from low frequency noise and even the presence of another similar track circuit 20km away [l]. This sort of interference also introduces difficulties in placing crossings close together such that the track circuits must overlap. Crossing indications are not fail-safe. Despite fail-safe detection logic existing systems do not confirm function so there is no explicit indication of system failure. Australian Standards allow only one type of active signal light at level crossings; the RX-5 assembly. The failure state of the RX-5 is the same as the safe state. The easiest way to improve the safety of level crossings would be to replace these dinosaurs with the equally venerable, but considerably safer, 3 aspect traffic light. Using Doppler radar Teknis has developed a fail-safe method of controlling level crossings which is low-cost, easy to install and maintain and requires no connection to the track.