Title | Capacities and Traffic Flow Characteristics of Rural and Suburban Multilane Highways in Taiwan Area (II) |
Dept | Transportation Technology and Information Division |
Year | 2004 |
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Summary | Published in May 2004 IOT SERIAL No. 93-59-1212, 314pp. The Institute of Transportation (IOT) is embarking on a three-year project to revise Chapter 11 of 2001 Taiwan Area Highway Capacity Manual for capacity analysis of rural and suburban multilane highways. Phase II of this project focuses on the operating characteristics of signalized intersections. The tasks carried out in this phase include: (1) collecting and analyzing supplemental field data to model the free-flow speeds in sections with uninterrupted traffic flows (2) establish fundamental relationships between flow rate and speed for analysis of sections with uninterrupted flows (3) establish a profile of peak-hour factor, vehicle mix, directional split of traffic volume, and lane distribution of vehicle types and directional movements (4) collect and analyze data related to queue discharge characteristics of unopposed movements (5) collect and analyze data related to travel time and speed in the acceleration zone downstream of a stop line and (6) use field data to calibrate Signalizing Expressway Simulation (SES) model. The field data collected in this phase show that queue discharge rate often keeps rising even after twenty queuing vehicles have been discharged. This characteristic contradicted the conventional conception that queue discharge rate would quickly reach a stable maximum after green onset. As a result, it became difficult to apply the traditional method of using saturation flow to estimate the capacities of the traffic lanes at a signalized intersection. A better method was recommended. Because of tremendous difficulties in developing analytical methods for analyzing the complex operations of signalized intersections, this phase of research was partially devoted to the development of a useful simulation model. The results of model calibration show that the SES model is able to duplicate realistically the observed queue discharge characteristics. Additional field data will be collected in the next phase to model traffic flows at signalized intersections and to further calibrate the SES model. The resulting simulation model will serve as a major tool for analysis of multilane highways. |
Post date | 2005/08/13 |
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