At Seattle-Tacoma International Airport, the new INNOVIA APM 100 automated people mover system entered service in May 2003 on the airport's North Loop Line and in November 2003 on the airport's South Loop and Shuttle Lines. A fleet of 21 INNOVIA APM 100 vehicles, custom-designed to fit the existing tunnels, replaces the first generation of vehicles originally supplied by Bombardier.
In operation since 1973, the people mover system consists of two loops - the North Loop and South Loop - and an interconnecting Shuttle Line. The loops offer a minute-long journey between each of the two satellite terminals and the Main Terminal, while the Shuttle provides a convenient link between the loops.
The APM deploys the CITYFLO 650 technology, a radio-based automatic train control system with overlay capability. This feature enabled passenger service to be maintained throughout the overall replacement and upgrade program, which was completed more than a year ahead of schedule.