00334174

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A computer program to detect vehicular incidents that occur on urban freeways during low-volume conditions was developed, tested, and evaluated. The type of incidents to be detected were those that involved vehicles that entered a freeway but, for some reason, did not pass through a defined study section. The algorithm can operate in real time and is based on an individual-vehicle input-output process. It was tested on traffic data from a four-lane section of freeway in Houston, Texas. The algorithm's performance was evaluated over a wide range of traffic volumes (100-1200 vehicles/h) and three different detector spacings--152.4, 304.8, and 457.2 m (500, 1000, and 1500 ft). In the 152.4-m section, the algorithm detected 65 percent (11/17) of the incidents that occurred. In the 304.8-m section, it detected 78 percent (14/18) of the incidents that occurred and, in the 457.2-m section, it detected 49 percent (17/35) of the incidents that occurred. Numerous lane changes and a bad detector at the first detection station caused the relatively poor performance of the algorithm in both the 152.4-m and the 457.2-m sections. The algorithm detected all incidents that occurred when the volume level was less than 400 vehicles/h. It detected 61 percent (37/61) of the incidents that occurred when the volume level was between 800 and 1200 vehicles/h. (Authors)

Publication of this paper sponsored by Committee on Freeway Operations.

01411593

pp 31-39

1980

Transportation Research Record

0309031176

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Figures (9) ; Maps (1) ; Photos (3) ; References (6) ; Tables (5)

Algorithms; Detection and identification; Detectors; Freeways; Spacing; Traffic crashes; Traffic incidents; Traffic volume; Urban highways; Vehicle detectors

Incidents

Highways; Operations and Traffic Management; I73: Traffic Control

TRIS, TRB

Oct 28 1981 12:00AM

• COUNTERMEASURES TO IMPROVE SAFETY AT MULTILANE RURAL INTERSECTIONS (ABRIDGMENT)
• EVALUATING THE SAFETY BENEFITS OF RAILROAD ADVANCE-WARNING SIGNS
• INVESTIGATION OF THE EFFECT OF LOCATION OF FREEWAY TRAFFIC SENSORS ON INCIDENT DETECTION
• LUMINAIRE PERFORMANCE ON ILLUMINATED OVERHEAD SIGNS (ABRIDGMENT)
• NIGHT VISIBILITY OF TRAINS AT RAILROAD-HIGHWAY GRADE CROSSINGS. ABRIDGMENT
• ON FORECASTING FREEWAY OCCUPANCIES AND VOLUMES (ABRIDGMENT)
• OPTIMUM LENGTH OF TWO-LANE TWO-WAY NO-PASSING TRAFFIC OPERATION IN CONSTRUCTION AND MAINTENANCE ZONES ON RURAL FOUR-LANE DIVIDED HIGHWAYS
• SELECTION AND EVALUATION OF OPTIMAL FREEWAY DESIGN BY COMPUTER SIMULATION
• TRANSVERSE PAVEMENT MARKINGS FOR SPEED CONTROL AND ACCIDENT REDUCTION (ABRIDGMENT)