Center for Advanced Transportation Education and Research University of Nevada, Reno Presenter: Cui Zhou University of Nevada, Reno Center for Advanced Transportation Education and Research March 27, Research Project for Nevada Department of Transportation Right-Turn Traffic Volume Reduction in Traffic Signal Warrant Analysis: A Delay Perspective

Center for Advanced Transportation Education and Research University of Nevada, Reno Presentation Overview 2  Introduction  Previous Research  ITE Community Discussion  Problems in Existing Methods  Proposed Methodology  Case Study  Summary and Conclusions

Center for Advanced Transportation Education and Research University of Nevada, Reno  Importance of Traffic Signal Warrants What’s traffic signal warrants?What’s traffic signal warrants? Standard: An engineering study of traffic conditions, pedestrian characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is justified at a particular location. Introduction 3

Center for Advanced Transportation Education and Research University of Nevada, Reno  Importance of Traffic Signal Warrants What’s traffic signal warrants?What’s traffic signal warrants? Standard: An engineering study of traffic conditions, pedestrian characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is 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 Introduction 4

Center for Advanced Transportation Education and Research University of Nevada, Reno  Importance of Traffic Signal Warrants What’s traffic signal warrants?What’s traffic signal warrants? Standard: An engineering study of traffic conditions, pedestrian characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is 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 Introduction 5 In short, traffic signals should be only installed when they will alleviate more problems than they induce.

Center for Advanced Transportation Education and Research University of Nevada, Reno  Right-turn Traffic in Traffic Signal Warrants Introduction 6 Less operational impact and faces fewer conflicting vehicles Make right turn without the aid of signals High volumes of right-turn traffic can skew a signal warrant analysis and indicate an incorrect need for a signal

Center for Advanced Transportation Education and Research University of Nevada, Reno  Right-turn Traffic in Traffic Signal Warrants Introduction 7 Less operational impact and faces fewer conflicting vehicles Make right turn without the aid of signals High volumes of right-turn traffic can skew a signal warrant analysis and indicate an incorrect need for a signal

Center for Advanced Transportation Education and Research University of Nevada, Reno  Right-turn Traffic in Traffic Signal Warrants Introduction 8 Less operational impact and faces fewer conflicting vehicles Make right turn without the aid of signals High volumes of right-turn traffic can skew a signal warrant analysis and indicate an incorrect need for a signal 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 Research University of Nevada, Reno Previous Research 9 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 Research University of Nevada, Reno Mozdba et al.: adjusted in one of three conditions: accident experience, sight distance obstruction and delay (EJ) ITE Journal Right turns are reduced based on the conflicting volume. The relationship is illustrated in a graph (AM) NCHRP Report 457 Illinois: Pagones Theorem, which uses a minor-street reduction and a mainline congestion factors to estimate the right-turn volume (AM) Wisconsin: base on minor street geometry (EJ) Los Angeles: right-turn vehicles delayed less than 45s (FO) Oregon: right-turn lane or shared lane capacity (EJ) Arizona: right-turn experiencing a stopped-delay of five seconds or less (FO) DOT Procedures Previous Research 10 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 Research University of Nevada, Reno ITE Community Discussion 11 Our topic was posted in the ITE community discussion section in October 2013 and eight responses were received in this survey Wisconsin and Illinois DOTs A consulting firm: NCHRP 457 Written Policies Federal Way: exclude right-turn volume if LOS was A Lee County(2): deduct left turns if there was a right-turn lane Virginia DOT: Pagones Theorem No Written Policies A gray area and more guidance will be helpful. Overrule included 100%, or on the other side excluded all of the right turns President of Yarger Engineering, Inc

Center for Advanced Transportation Education and Research University of Nevada, Reno   Most of them are based on engineering judgments Problems In Existing Methods 12

Center for Advanced Transportation Education and Research University of Nevada, Reno   Most of them are based on engineering judgments   Pagones Theorem and NCHRP methods are relatively sound Problem In Existing Methods 13

Center for Advanced Transportation Education and Research University 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 Methods 14

Center for Advanced Transportation Education and Research University of Nevada, Reno   The approach is based on delay equivalence Find the delay equivalent relationship between right-turn and through traffic Methodology 15

Center for Advanced Transportation Education and Research University of Nevada, Reno   The approach is based on delay equivalence Find the delay equivalent relationship between right-turn and through traffic Methodology 16

Center for Advanced Transportation Education and Research University 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 Methodology 17

Center for Advanced Transportation Education and Research University of Nevada, Reno   An isolated intersection is studied Methodology 18 Directional ratio= WB Volume: EB Volume

Center for Advanced Transportation Education and Research University of Nevada, Reno   An isolated intersection is studied   Five minor-street lane conditions are discussed Methodology 19

Center for Advanced Transportation Education and Research University of Nevada, Reno   Different traffic volume scenarios are applied (12,096 cases in total) Condition 1 20

Center for Advanced Transportation Education and Research University of Nevada, Reno   Different traffic volume scenarios are applied (12,096 cases in total) Condition 1 21 One Study Situation 20% LT

Center for Advanced Transportation Education and Research University of Nevada, Reno   Different traffic volumes scenarios are applied (12,096 cases in total)   The reduction factor could be calculated: Condition 1 22

Center for Advanced Transportation Education and Research University of Nevada, Reno Condition 1 23 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 Research University of Nevada, Reno Condition 1 24 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 Research University of Nevada, Reno Condition 1 25  Reduction Factor Table

Center for Advanced Transportation Education and Research University 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 2 26

Center for Advanced Transportation Education and Research University 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 3 27

Center for Advanced Transportation Education and Research University of Nevada, Reno Condition 3 28  Reduction Factor Table

Center for Advanced Transportation Education and Research University of Nevada, Reno Condition 4 29  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 Research University of Nevada, Reno Condition 4 30  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 Research University of Nevada, Reno Condition 4 31  Reduction Factor Table

Center for Advanced Transportation Education and Research University of Nevada, Reno   Because there is exclusive left-turn lane, left-turn traffic is not considered in this condition.   Reduction Factor Table Condition 5 32

Center for Advanced Transportation Education and Research University 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 Study 33

Center for Advanced Transportation Education and Research University 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 Study 34

Center for Advanced Transportation Education and Research University of Nevada, Reno Case Study: Lamoille Hwy and Spring Creek Pkwy 35 Lamoille Hwy Spring Creek Pkwy

Center for Advanced Transportation Education and Research University of Nevada, Reno Case Study: Lamoille Hwy and Spring Creek Pkwy 36

Center for Advanced Transportation Education and Research University of Nevada, Reno Case Study: US395 and Airport Rd 37 US395 Airport Rd

Center for Advanced Transportation Education and Research University of Nevada, Reno Case Study: Lamoille Hwy and Spring Creek Pkwy 38

Center for Advanced Transportation Education and Research University of Nevada, Reno   Unwarranted traffic signals are detrimental Summary and Conclusions 39

Center for Advanced Transportation Education and Research University of Nevada, Reno   Unwarranted traffic signals are detrimental   Engineers agree on reducing right-turn volumes, but there is no mature guidance Summary and Conclusions 40

Center for Advanced Transportation Education and Research University 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 Conclusions 41

Center for Advanced Transportation Education and Research University 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 Conclusions 42

Center for Advanced Transportation Education and Research University 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 Conclusions 43

Center for Advanced Transportation Education and Research University of Nevada, Reno Thank you for listening! 44