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Research Project for Nevada Department of Transportation. Right-Turn Traffic Volume Reduction in Traffic Signal Warrant Analysis: A Delay Perspective. Present e r: Cui Zhou University of Nevada, Reno Center for Advanced Transportation Education and Research March 27 , 2014. - PowerPoint PPT Presentation
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Presenter: Cui ZhouPresenter: Cui ZhouUniversity of Nevada, RenoUniversity of Nevada, Reno
Center for Advanced Transportation Education and ResearchCenter for Advanced Transportation Education and ResearchMarch 27, 2014March 27, 2014
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Research Project for Nevada Department of TransportationResearch Project for Nevada Department of Transportation
Right-Turn Traffic Volume Reduction in Right-Turn Traffic Volume Reduction in Traffic Signal Warrant Analysis: A Delay PerspectiveTraffic Signal Warrant Analysis: A Delay Perspective
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Presentation OverviewPresentation Overview
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IntroductionIntroduction Previous ResearchPrevious Research ITE Community DiscussionITE Community Discussion Problems in Existing MethodsProblems in Existing Methods Proposed MethodologyProposed Methodology Case StudyCase Study Summary and ConclusionsSummary and Conclusions
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Importance of Traffic Signal WarrantsImportance of Traffic Signal Warrants• What’s traffic signal warrants?What’s traffic signal warrants?Standard: An engineering study of traffic conditions, pedestrian Standard: An engineering study of traffic conditions, pedestrian
characteristics, and physical characteristics of the location shall be characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control performed to determine whether installation of a traffic control signal is justified at a particular location.signal is justified at a particular location.
IntroductionIntroduction
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Importance of Traffic Signal WarrantsImportance of Traffic Signal Warrants• What’s traffic signal warrants?What’s traffic signal warrants?Standard: An engineering study of traffic conditions, pedestrian Standard: An engineering study of traffic conditions, pedestrian
characteristics, and physical characteristics of the location shall be characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is performed to determine whether installation of a traffic control signal is justified at a particular location.justified at a particular location.
• Consequences of an unwarranted signalConsequences of an unwarranted signal• Rear-end collisionsRear-end collisions• Excessive delay and congestionExcessive delay and congestion• Disobedience of signalsDisobedience of signals
IntroductionIntroduction
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Importance of Traffic Signal WarrantsImportance of Traffic Signal Warrants• What’s traffic signal warrants?What’s traffic signal warrants?Standard: An engineering study of traffic conditions, pedestrian Standard: An engineering study of traffic conditions, pedestrian
characteristics, and physical characteristics of the location shall be characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is performed to determine whether installation of a traffic control signal is justified at a particular location.justified at a particular location.
• Consequences of an unwarranted signalConsequences of an unwarranted signal• Rear-end collisionsRear-end collisions• Excessive delay and congestionExcessive delay and congestion• Disobedience of signalsDisobedience of signals
IntroductionIntroduction
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In short, traffic signals should be only installed when they will alleviate more problems than they induce.
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Right-turn Traffic in Traffic Signal WarrantsRight-turn Traffic in Traffic Signal Warrants
IntroductionIntroduction
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Right-turn Traffic in Traffic Signal WarrantsRight-turn Traffic in Traffic Signal Warrants
IntroductionIntroduction
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Right-turn Traffic in Traffic Signal WarrantsRight-turn Traffic in Traffic Signal Warrants
IntroductionIntroduction
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MUTCD and MTSD have clearly stated that some portion of the right-turn traffic should be reduced from the minor street traffic count.
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Previous ResearchPrevious Research
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Right-turn adjustments are usually based on engineering judgment (EJ), field observation (FO), or an accepted right-turn
adjustment methodology (AM).
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Previous ResearchPrevious Research
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Right-turn adjustments are usually based on engineering judgment (EJ), field observation (FO), or an accepted right-turn adjustment methodology
(AM).
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
ITE Community DiscussionITE Community Discussion
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Our topic was posted in the ITE community discussion section in October 2013 and eight responses were received in this survey
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Most of them are based on engineering judgments
Problems In Existing MethodsProblems In Existing Methods
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Most of them are based on engineering judgments
Pagones Theorem and NCHRP methods are relatively sound
Problem In Existing MethodsProblem In Existing Methods
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Most of them are based on engineering judgments
Pagones Theorem and NCHRP method are relatively sound • The intersection’s LOS after reduction is often one alphabet better • Pagones Theorem fails to take into account the uneven volume
distribution • The NCHRP method works out the reduction based on the
conflicting major-road. It doesn’t give any thought to the through and left turn traffic
Problem In Existing MethodsProblem In Existing Methods
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
The approach is based on delay equivalence• Find the delay equivalent relationship between right-turn
and through traffic
MethodologyMethodology
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
The approach is based on delay equivalence• Find the delay equivalent relationship between right-turn
and through traffic
MethodologyMethodology
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
The approach is based on delay equivalence• Find the delay equivalent relationship between right-turn
and through traffic
The estimation of control delay is implemented in VBA programming in EXCEL according to HCM 2010
MethodologyMethodology
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
An isolated intersection is studied
MethodologyMethodology
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Directional ratio=WB Volume: EB Volume
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
An isolated intersection is studied
Five minor-street lane conditions are discussed
MethodologyMethodology
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Different traffic volume scenarios are applied (12,096 cases in total)
Condition 1Condition 1
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Different traffic volume scenarios are applied (12,096 cases in total)
Condition 1Condition 1
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One Study Situation
20% LT20% LT
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Different traffic volumes scenarios are applied (12,096 cases in total)
The reduction factor could be calculated:
Condition 1Condition 1
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 1Condition 1
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The reduction factor graph in one specific study situation where the mainline volume is 500 vph with 1:1 directional ratio
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 1Condition 1
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The reduction factor graph in one specific study situation where the mainline volumes are 500 vph with 1:1 directional ratio
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 1Condition 1
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Reduction Factor Table Reduction Factor Table
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Using the same traffic volume scenarios, almost the same reduction factors are obtained
From here, we could also see that the assumed left-turn percentage doesn’t significantly affect the equivalent results
Condition 2Condition 2
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
20 left turns and zero through traffic are assumed before reduction. The right-turn movement volume is from 50 vph to 510 vph with 20 vph increment
The adjusted minor street volume is the maximum of adjusted right-turn and through & left-turn traffic ( critical volume)
Condition 3Condition 3
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 3Condition 3
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Reduction Factor Table Reduction Factor Table
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 4Condition 4
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Minor street left-turn and through volume is from 40 vph to 700 vph with 20 vph increment
Reduction factor graph when the mainline volume is 500 vph.
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 4Condition 4
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Minor street left-turn and through volume is from 40 vph to 700 vph with 20 vph increment
Reduction factor graph when the mainline volume is 500 vph.
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Condition 4Condition 4
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Reduction Factor Table
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Because there is exclusive left-turn lane, left-turn traffic is not considered in this condition.
Reduction Factor Table
Condition 5Condition 5
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
26 intersections’ turning volumes provided by NDOT
According to 8 hour warrant in MUTCD, divide these cases into three categories:• warrant meets without right turning (7 cases) ;• warrant doesn’t meet with all turning movement (12
cases); • warrant meets when considering all turning movement
(7 cases)
Case StudyCase Study
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
26 intersections’ turning volumes provided by NDOT
According to 8 hour warrant in MUTCD, divide these cases into three categories:• warrant meets without right turning (7 cases) ;• warrant doesn’t meet with all turning movement (12
cases); • warrant meets when considering all turning movement
(7 cases)
Case StudyCase Study
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Case Study: Lamoille Hwy and Spring Creek Pkwy
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Lamoille Hwy
Spring Creek Pkwy
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Case Study: Lamoille Hwy and Spring Creek Pkwy
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Case Study: US395 and Airport Rd
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US395 Airport Rd
Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Case Study: Lamoille Hwy and Spring Creek Pkwy
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Unwarranted traffic signals are detrimental
Summary and ConclusionsSummary and Conclusions
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Unwarranted traffic signals are detrimental Engineers agree on reducing right-turn volumes, but
there is no mature guidance
Summary and ConclusionsSummary and Conclusions
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Unwarranted traffic signals are detrimental Engineers agree on reducing right-turn volumes, but
there is no mature guidance This paper proposed a new guideline which is based
on the equivalent relation when right turns and through traffic achieve the same delay
Summary and ConclusionsSummary and Conclusions
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Unwarranted traffic signals are detrimental Engineers agree on reducing right-turn volumes, but
there is no mature guidance This paper proposed a new guideline which is based
on the equivalent relation when right turns and through traffic achieve the same delay
Five conditions are divided, and further 63 study situations are provided in each condition
Summary and ConclusionsSummary and Conclusions
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Unwarranted traffic signals are detrimental Engineers agree on reducing right-turn volumes, but
there is no mature guidance This paper proposed a new guideline which is based
on the equivalent relation when right turns and through traffic achieve the same delay
Five conditions are divided, and further 63 study situations are provided in each condition
Case studies were conducted. The proposed guideline can easily help engineers make sound decisions for the adjustment of right turns
Summary and ConclusionsSummary and Conclusions
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Center for Advanced Transportation Education and ResearchUniversity of Nevada, Reno
Thank you for listening!Thank you for listening!
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