What makes intelligent vehicles smart? The ability of a vehicle to ‘know’ where it is at any given moment is one measure of intelligence that enables a host of intelligent transportation systems applications, from basic navigation assistance to automatic collision warning.
Many vehicle location and positioning applications are built around Global Positioning System (GPS) technology, which, in theory, provides the capability to locate a GPS-equipped vehicle anywhere on the Earth’s surface. However, in practice, GPS is limited by the need for clear ‘views’ of orbiting satellites; bridges, tunnels, and the urban canyons of downtown areas can block or interfere with GPS signals, resulting in unacceptable gaps in service.