In 1998, transmission balise-locomotive (TBL) was implemented on the East Rail line to monitor train safety. Subsequently, in 2002, ATO was also implemented on the East Rail line. However, the original British-style Automatic Warning System is still retained for use by Intercity-Through Trains. On the other hand, the West Rail and Tuen Ma lines use SelTrac moving block communications-based train control (CBTC) system from Alcatel Canada (now Thales Group). The SelTrac system is also used by the fully automated Disneyland Resort line, whereas the South Island line uses another signalling supplier, Alstom, Urbalis 400 CBTC system.