@article{ref1,
title="Detecting freeway incidents under low-volume conditions",
journal="Transportation research record",
year="1975",
author="Messer, Carroll J. and Ritch, Gene P. and Weaver, Graeme D. and Dudek, Conrad L.",
volume="533",
number="",
pages="34-47",
abstract="Two computer algorithms for automatic, freeway-incident detection under low-volume conditions were developed. The first approach uses a time-scan process. The second approach, considered to be superior to the first, operates on an event-scan principle. Computer simulations produced a family of curves that are useful in determining sensor- spacing requirements for an operational system using the event-scan algorithm. The results indicate that, when detector spacings of 1,000 ft (304.8 m) are used, all incidents on a 3-lane freeway section can be detected within 3 min for volumes up to 500 vehicles per hour. When volumes approach 1,000 vehicles per hour, 85 percent of the incidents can be detected within 3 min. Faster detection capabilities at the higher volumes would require closer detector spacings. Incident-detection operational considerations, particularly the manner in which software can be developed to recognize and compensate for vehicle-count errors produced by semitrailers and lane-change maneuvers, also are discussed.<p />",
language="en",
issn="0361-1981",
doi="",
url="http://dx.doi.org/"
}