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DEVELOPMENT OF A SIMULATION MODEL FOR FREEWAY WEAVING SECTIONS

Posted on:1988-09-05Degree:Ph.DType:Dissertation
University:The Ohio State UniversityCandidate:ZAREAN, MOHSENFull Text:PDF
GTID:1472390017457735Subject:Engineering
Abstract/Summary:
At freeway weaving sections two traffic streams merge and then diverge within a comparatively short distance. This research involved the development and validation of a microscopic simulation model (WEAVSIM) to study the dynamics of traffic flow at weaving sections.;The Federal Highway Administration (FHWA) supplied data collected, using time-laps aerial photography, at several freeway weaving sections. These data sets facilitated the development and validation of WEAVSIM.;WEAVSIM utilizes the event-scheduling approach of SIMSCRIPT II.5 which is a free-format, English-like programming language. It is throughly commented for easy understanding of the logic and its computer time requirements are reasonable when compared to similar traffic simulation models.;WEAVSIM is based on a rational description of the behavior of the driver-vehicle units in a freeway weaving station. Vehicles are generated randomly at the system entry points and are advanced through the system in accordance with their desired speed and destination, influenced by the immediate environment. A car-following algorithm governs longitudinal movements and a lane-changing algorithm controls lateral movements.;The input modeling of WEAVSIM includes the random assignment of vehicles' attributes from some generally accepted frequency distributions, as well as some roadway parameters representing the geometry of the simulated weaving section. The output of the model includes an echo of the input parameters and statistics on measures of performance of the weaving section. The model has the capability of graphical presentation of these statistics.;Validation of the model included the operational testing of the car-following algorithm and the comparison of the simulated observations with field data. Overall, the validation results indicate that the model reproduces behavior of the real-life systems quite accurately. A sensitivity analysis of the output to variation in the input variables was also performed with satisfactory results.;WEAVSIM was used in a simulation study the objective of which was to investigate the impact of upstream conditions, represented by the arrival speeds of the two merging traffic streams, on the operational conditions at the weaving sections. The simulation study revealed that the differences in arrival speeds has direct impact on the speeds and delays computed at weaving sections.
Keywords/Search Tags:Weaving sections, Model, Simulation, Development, Traffic
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