A PUBLIC PRIORITY: AALBORG'S BUS PRIORITY EXPLAINED

The Danish city of Aalborg has introduced a traffic signal priority system for its buses, in an attempt to encourage its motorists to use them, thereby reducing traffic congestion and air pollution. Infocom Systems A/S has introduced the system used by bus routes 10 and 11, which run on a north-south road with 27 signal-controlled junctions. The system requirements included: (1) two-way radio communication between controllers and buses; (2) automatic transfer of data, including driver schedules and programs, to and from the bus computer; and (3) the ability to supply real-time information to passengers in buses and at bus stops, and monitor bus operation centrally. Infocom selected a system based on a global positioning system (GPS), and on data transmission via a radio network and Infocom's Unibox bus computer. A bus driver inputs details of the current trip and a journey number identifying the trip to the bus computer, and is continually informed whether the bus is ahead of schedule or behind schedule. Activation of appropriate traffic signal controllers is based on GPS location of the bus. The central unit sends new driving schedules and location reports to buses and controllers, respectively. The system has many advantages, and is expected to improve service regularity and ease pressure on drivers.