Capacity Analysis of Traffic-Actuated Intersections Final Report (1996) / Chapter Skim
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1 INTRODUCTION AND RESEARCH APPROACH
1 INTRODUCTION AND RESEARCH APPROACH
Pages 5-12
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From page 5... ...
This methodology is widely used both nationally and internationally and approaches a standard for the evaluation of the performance of signalized intersections in the U.S.A The HCM is maintained by the Transportation Research Board (TRB) Committee on Highway Capacity and Quality of Service, often referred to as the "Highway Capacity Committee." Working towards a major revision ofthe HCM in the year 2000, the Highway Capacity Committee has embarked on a comprehensive research program to overcome oenc~enc~es In all chapters, and to serve the needs of transportation professionals in an environment of advanced technology.
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From page 6... ...
The scope of the study was not intended to be all-inclusive, but was limited instead to the most typical signalized intersection designs using actuated controllers. NCHRP Project 3-48 Final Report: Page 6
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From page 7... ...
It is note however, possible to avoid the burden ofadditionaldataifan analytically defensible model for traffic-actuated operationisto be produced. This is especially true if the model is to respond to changes in the design parameters of traff~c-actuated control.
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From page 8... ...
On the other hand, the analytical tools offer a much better insight into the operation of a given facility because they provide access to intermediate computations. For example, the analytical tools provide a direct estimate of the capacity of an approach to a signalized intersection, in addition to measures such as opposing queue service times for permitted led turns, progression adjustment factors, etc.
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From page 9... ...
There has been a substantial amount of research conducted on traff~c-actuated control related to this project. The main topics of this literature review included: Traffic-actuated control definitions, Warrants for traffic-actuated control, Benefits and operating considerations for traffic-actuated control, Effects of coordination and phase-skipping for traff~c-actuated control, Late-night, low-volume operation of coordinated actuated systems, Evaluation of traff~c-actuated control by simulation, Estimation of green times and cycle length for traffic-actuated control Delay models for traff~c-actuated control, · Signalized intersection capacity models for traffic-actuated control, and · Overview and evaluation of "Enhancement of the Value Iteration Program for Actuated Signals" (EVIPAS)
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From page 10... ...
Examples of design parameters include: I. Traffic-actuated controller settings (initial interval, allowable gap, maximum green time)
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From page 11... ...
More importantly, they provide a standardized structure for presenting the results of intermediate computations in a common form that is compatible with the prescribed techniques. The main feature that unifies all HCM Chapter 9 related software products today is that they all produce their output in the form of the standard HCM worksheets.
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From page 12... ...
The results, which are reported In the next chapter, were very encouraging. These results demonstrate the clear superiorly ofthe proposed analytical mode} relative to the existing methodology.
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