Automobile congestion in major
cities has become unacceptable, and advanced traffic management systems are
being built in many of these cities to measure traffic flow at intersections
(by some combination of magnetic loop detectors, optical sensors, and other
means), and regulate stoplights and message signs. These systems can also issue
advisories of accidents ahead by means of variable message signs or radio, and
give advice of alternative routings. In emergencies they can dispatch fire,
police, ambulances, or tow trucks, and in the case of tunnels can shut down
entering traffic completely if necessary. These systems are operated by a
combination of computers and humans from centralized control rooms. The
operators look at banks of video monitors which let them see the traffic flow
at different locations, and computer-graphic displays of maps, alarm windows,
and textual messages. The operators get advice from computer-based expert
systems, which suggest best responses based on measured inputs, and the
operator must decide whether to accept the computer’s advice, whether to seek further
information, and how to respond.
