Also called People Movers, Automated Guideway Transit (AGT) refers to a system in which speed, spacing, and other functions are automatically controlled. No drivers are used. A requirement for AGT is exclusive right-of-way. Two types of AGT are:
Group Rapid Transit (GRT): This consists of moving blocks of riders with common origins and destinations. Large vehicles can be used. Off-line stations, while not required, would be desireable. All presently existing AGT systems are GRT.
Personal Rapid Transit (PRT): Small vehicles are used (2-6 people) to transport individual parties directly from origin to destination, thus eliminatiing intermediate stops. Off-line stations are required. An optimum system would consist of a network of lines. PRT has been demonstrated, but no operational system has yet been constructed.
The Modern Transit Society wrote an article in the early 1970's called Light Transit which is still applicable.