Title Traffic Flow Characteristics of Toll Plazas, Tunnels, and Upgraded Segments on Freeways and other Roadways (2/3)
Dept Transportation Planning and Land Transport Division
Year 2012
Month
Price
Summary In 2010, the Institute of Transportation initiated a three-year project to investigate the traffic flow characteristics at toll plazas, road tunnels, and freeway grade sections. Phase 2 of this project involves four tasks. The first uses detector data to analyze the traffic flow characteristics of the road tunnels on National highway 5. Based on the findings of the first task, the second task will develop a new chapter for inclusion in the Taiwan Highway Capacity Manual (HCM) to facilitate capacity and level-of-service analysis of road tunnels. The third task focuses on exploring the characteristics of free-flow speeds and queue discharge headways that may be affected by the presence of short depressed street sections. The data collected under this task will be used to revise the HCM methodology being used for analyzing depressed urban streets. The final task is an extension of the ongoing effort to collect free-flow speed data on freeway grade sections. In Phase 2, such data are used to test and calibrate the Traffic Speed Simulation (TSS) model. The TSS model can be incorporated into a full-fledged model for analyzing traffic operations on grade sections. Phase 2 of the project identifies the capacities and the characteristic speed-flow relationships at various locations along National Highway 5. It develops a methodology for analyzing traffic operations in road tunnels based on the speed-flow relationships in tunnels and the propagation of shockwaves generated at the junctions between freeway main lines and on-ramps. Field data reveal that depressed urban streets can affect the operating efficiencies of downstream signalized intersections. Therefore, a new methodology for analyzing depressed urban streets needs to be developed. Finally, the TSS model is found to be able to realistically duplicate the free-flow characteristics of large vehicles on long and short grade sections. This report details the findings of the aforementioned tasks.
Post date 2012/09/07
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