A European first at Clermont-Ferrand in France, Cegelec Transport installed the SIL4 (Safety Integrity Level 4) standard for a rubber-tyre tramway system – no existing solution for signalling and no applicable standard existed at the time. The key points: the full development of innovative detection system based on loop circuits; the use of electronic interlocking; and SIL 4 for both detection and interlocking.