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Citation |
Smith SA, Roskin ME. Transp. Res. Rec. 1985; 1005: 121-128. |
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Copyright |
(Copyright © 1985, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing) |
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DOI |
unavailable |
PMID |
unavailable |
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Abstract |
The methodologies employed in an FHWA research study entitled "Freeway Data Collection for Studying Vehicle Interactions" are described. The purpose of this study was to develop a series of data sets on microscopic vehicular traffic flow for selected types of freeway sections. The methodology used to develop these data sets involved digitizing vehicle positions from time-lapse aerial photographs of a series of freeway sites with various geometric configurations. Six types of freeway geometry were of interest: ramp merges, weaving sections, upgrade sections, reduced-width sections, lane drops, and horizontal curves. The aerial photography involved the use of a full-frame 35-mm motion picture camera operating in time-lapse mode mounted in a fixed-wing, short-takeoff-and-landing (STOL) aircraft. The sites were filmed at one frame per second with the aircraft flying clockwise at a slow speed around each site at altitudes ranging between 2,500 and 4,500 ft. Data were reduced to 1 hour of film (3,600 frames) of each site. Sites ranged between 1,200 and 3,200 ft in length. The data reduction method involved a microcomputer-based digitizing system. The most important components of the system were the mathematical techniques for computing vehicle position and the method of vehicle matching, which yielded complete vehicle trajectories for all vehicles passing through the sections studied. The data sets are expected to be useful both for empirical research on freeway traffic flow and for the validation of freeway simulation models. The data sets are being made available to those conducting research in these areas. Language: en |
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Keywords |
MOTOR TRANSPORTATION; VEHICLES - Performance; AERIAL PHOTOGRAPHY - Computer Applications; DATA PROCESSING - Data Acquisition; HIGHWAY SYSTEMS - Monitoring |