singapore has had other various forms of light urban rail systems, such as the monorail system on sentosa island, which opened in february 1982. this 6.4 km, 6-station system was closed in march 2005 and a new sentosa express system was built by december 2006. the changi skytrain, a people mover system shuttling passengers between the three terminals at the singapore changi airport, was opened originally in 1990 along with terminal 2 and upgraded in 2006 with the completion of terminal 3. the jurong birdpark previously featured an air-conditioned panorail which closed in 2012.