Capacity and Level of Service at Unsignalized Intersections Final Report Volume 1 - Two-Way-Stop-Controlled Intersections (1996) / Chapter Skim
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Chapter Nine. Control Type, Queuing, and LOS Issues
Chapter Nine. Control Type, Queuing, and LOS Issues
Pages 111-122
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From page 111... ...
Practicing traffic engineers can refer to these warrants whenever issues arise regarding decisions on intersection control type ;. The MUTCD is c~Tcuttr~dergo~ng a revision due for publication in 1996.
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From page 112... ...
For TWSC intersections, Minor ~ is the highest volume subject approach and Major ~ is He major street approach on the leR side of the subject approach For AWSC intersections, Major ~ is always the approach I the highest volume, and Minor ~ is the approach on the right hand side of He Major ~ approach. For He purpose of companson, the volume split on the minor street was based on the conditions usually observed at TWSC Neons.
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From page 113... ...
Two peak hour warrant curves from the MUTCD were plotted on the figure for later comparison. Figure 65 illustrates He best intersection control type based on the minimum intersection delay per vehicle.
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From page 114... ...
Average Total ~tersection Delay for Different Control Types
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From page 115... ...
Op~num Control Type Based on Minimum Average Idtersection Delay
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From page 116... ...
Optimum Control Type Based on the Minimum Average Intersection Delay and a 5-Second Significant Difference Level Another set offigures was developed based on intersection level of service. The HEM uses different delay thresholds to designate level of service based on vehicle delay.
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From page 117... ...
Intersechon Level of Servic\e a`OS) for Different Control Types
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From page 118... ...
Optimum Control Type Based on Intersection LOS The result of the sample calculations show that, for the given assumptions of turning movement proportions, geometry and signal parameters, Here is a fairly good correlation between the MUTED signal peak hour signal warrants and He result obtained based on the operational assessment through~e HCM delay models. However, the HCM probes provide a useful too} for traffic engineers to deal with more specific and diverse traffic and geometric conditions when determining intersection control type.
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From page 119... ...
For a typical four-lane arterial wig average daily traffic volumes in the range of 15,000 to 20,000 vehicles per day (peak hour 1,500 to 2,000 veldt) , the delay equation used in the TWSC capacity analysis procedure will predict 45 seconds of delay or more ([eve!
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From page 120... ...
that includes v/c ratios less than 1.0 and average delays "mater than 45 seconds. In this region, Me average queue length is typically less than one vehicle, which indicates ~at, although Rivers would likely experience relatively long delays, it is unlikely that long queues would form due to the low demand volumes.
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From page 121... ...
The potential for making inappropriate traffic control decisions is likely to be particularly pronounced when Me HEM level of service thresholds are adopted as a legal standards, as is the case mmany public agencies. ~ recognition of the importance the level of senice designation has assumed in making haiTic control decisions, it may be appropriate to either reconsider the delay thresholds, or reconsider the concept of level of service for the overall intersection based solely on the worst movement, or both.
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