Rail transport in Singapore exists in three main types, namely an international rail connection operated by Malaysian company Keretapi Tanah Melayu (KTM), a rapid transit system collectively known as the Mass Rapid Transit (MRT) system operated by the two biggest public transport operators SMRT Trains (SMRT Corporation) and SBS Transit, as well as several Light Rail Transit (LRT) lines also operated by both companies. In addition, local specialised light rail lines are in operation in places such as the Singapore Changi Airport and Sentosa.