Denver International Airport Automated Guideway Transit System Denver International Airport Automated Guideway Transit System The Denver International Airport Automated Guideway Transit System is a people mover system operating at Denver International Airport in Denver, Colorado. The system opened along with the airport itself in 1995, and was conceived as a means to connect all of the midfield concourses with the south terminal and quickly transport passengers between them because of the longer distances between each building, especially when compared to Stapleton International Airport, Denver's former airport. Located within the secure areas of the airport, the AGTS utilizes two mile-long tunnels traveling underneath the aircraft taxiways and passing
Stapleton International Airport officially opened for all operations the following morning. When it closed in 1995, Stapleton had six runways (2 sets of 3 parallel runways) and five terminal concourses. The runways at Stapleton were then marked with large yellow "X"s, which indicated it was no longer legal or safe for any aircraft to land there. The IATA and ICAO airport codes of DEN and KDEN were then transferred to the new DIA, to coincide with the same changes in airline and ATC computers, to ensure that flights to Denver would land at the new DIA. While Denver International was being constructed, planners