A SIGNAL TIMING DESIGN PROPOSAL FOR SIGNALIZED ROUNDABOUTS

A SIGNAL TIMING DESIGN PROPOSAL FOR SIGNALIZED ROUNDABOUTS DR. YETIS SAZI MURAT PAMUKKALE UNIVERSITY DENIZLI-TURKEY Weekly Seminar Program of Transportation Research Group 09/28/2017

BIOGRAPHY Working Experience 2013- Professor (Tenure Track), Pamukkale University, Dept. of Civil Eng., Turkey 2007-2013- Associate Professor, Pamukkale University, Dept. of Civil Eng., Turkey 2006-(6 months)- Visiting Scholar, Virginia Politechnic Institute and State University, Falls Church, Virginia, USA 2002-2007- Assistant Professor, Pamukkale University, Dept. of Civil Eng., Turkey 2000-2002- Research Assistant, Istanbul Technical University, Faculty of Civil Eng., Istanbul, Turkey 1994-2000- Research Assistant, Pamukkale University, Faculty of Eng., Civil Eng. Dept., Denizli, Turkey Educational Background 1996-2001, PhD. in Transportation Eng., Institute of Natural and Applied Sciences, Istanbul Technical University, Istanbul, Turkey 1994-1996, MSc. in Civil Eng., Institute of Natural and Applied Sciences, Pamukkale University, Denizli, Turkey 1992-1993, English Prep. Class, Institute of Natural and Applied Sciences, Dokuz Eylul University, Izmir, Turkey 1988-1992, BSc in Civil Eng., Dokuz Eylul University, Faculty of Eng., Dept. of Civil Eng., Izmir, Turkey 2

PUBLICATIONS 2 Book editoral 6 Book chapters 14 SCI indexed papers 14 Other indexed papers 43 Conference proceedings 7 Other papers Traffic Signal Control Traffic Operation and management Traffic Flow Theory Public Transportation Traffic Safety 3

PROJECTS Research Projects Research Project of the Scientific and Technical Research Council of Turkey (TUBITAK), Project No: INTAG 915, A Fuzzy Logic Traffic Signal Control Model for Isolated Signalized Intersections (Main Researcher, completed), 2002. Research Project of the Pamukkale University Scientific Research Center (PAUBAP), Project No: 2003MHF008, Application of Intelligent Traffic Signal Control Models on Real Intersections (Director of the project, completed). Research Project of the Pamukkale University Scientific Research Center (PAUBAP), Project No: 2003MHF006, Estimation of Earthquake Losses using Geographical Information System (Main Researcher, completed), 2006. Research Project of the Pamukkale University Scientific Research Center (PAUBAP), Project No: 2003MHF009, Traffic Control and Network Management (Main Researcher, completed). Research Project of the Scientific and Technical Research Council of Turkey (TUBITAK), Project No: 105G090, Crime Analysis Modelling at Denizli Province (Main Researcher, completed), 2009. Research Project of the Scientific and Technical Research Council of Turkey (TUBITAK), Project No: 110M677, Investigation of Driver Behavior Effects on Capacity and Intersection Performance at Urban Roads (2011-2014) Research Project of the Scientific and Technical Research Council of Turkey (TUBITAK), TEYDEB, "Development of Full Adaptive Traffic Signal Control System for Isolated and Coordinated Signalized Intersections" (2010-2012) EU Projects Title: EURO-GIS: Mobility for Civil Engineering Students (as Coordinator with Selcuk TOPRAK) Project Type: Leonardo Da Vinci Program (Project No: TR/04/A/F/PL2-029) Period: 2 years (completed) Funding agency: European Commission-The Centre for European Union Education and Youth Programs in Turkey 4

THESIS SUPERVISED Supervised MSc. Thesis: Demirkollu, M. (2017). Determination of Bus Service Frequency by Linear Goal Programming MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 18.04.2017, Denizli, Turkey Altintas, N.C., (2017). `Development of a Database with GIS for Construction, Maintenance and Repair of Urban Roads` MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 08.01.2017, Denizli, Turkey Sunnetci, H., (2017). `Investigation of the Relation of Delay parameter (k) and Cycle Time at Signalized Intersections`, MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 12.05.2017, Denizli, Turkey Topcuoglu, D. (2017). `Modelling Flow Rutting on Pavements with Finite Element Method` MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 10.01.2017, Denizli, Turkey Cakici, Z., (2014) Investigation of Design Procedure of Roundabouts with Signals, MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 11.07.2014, Denizli, Turkey Demirkiran, O., (2013) `Investigation of Level of Services at Pedestrian Areas` MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 05.12.2013, Denizli, Turkey Yaslan, G. (2012). "Fuzzy Logic based Ramp Metering Model for Freeways and Highways", MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 05.07.2012, Denizli, Turkey Saldiroglu, S. (2010). A GIS based Village Roads Management Model for Monitoring, Maintenance and Repairing Purposes, MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 22.07.2010, Denizli, Turkey Şekerler, A. (2008). Analysis of Traffic Accidents using Fuzzy Clustering Approach, MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 23.07.2008, Denizli, Turkey. Uludağ, N., (2005). Route Choice Behavior Modelling of Road Users at Denizli Urban Road Network", MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 04.08.2005, Denizli, Turkey Başkan, Ö., (2004). Modelling Vehicle Delays at Isolated Signalized Intersections using Artificial Neural Networks", MSc. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 30.06.2004, Denizli, Turkey. (Awarded by Turkish Road Association as MSc. Thesis for the year of 2005) Supervised PhD. Thesis: Cetin, M. (2015). Mathematical modeling of Saturation Flow at Signalized Intersections. Ph.D. Thesis, Pamukkale University Institute of Natural and Applied Sciences, Denizli, Turkey. Uludağ, N., (2010). Modelling of Bus Lines using Fuzzy Optimization and Linear Goal Programming Ph.D. Thesis, Pamukkale University Institute of Natural and Applied Sciences, 21.07.2010, Denizli, Turkey. 5

TURKEY, PAMUKKALE UNIVERSITY AND DENIZLI 6

Elazig 7

WHERE I AM LIVING? 8

PAMUKKALE-DENIZLI 9

HIERAPOLIS 10

PAMUKKALE UNIVERSITY 61311 Students 1913 Academicians 1490 Other Staffs 70 acres Campus MY OFFICE https://youtu.be/rbmo7m2lbqq PAU 11

RESEARCH OUTLINE Aim Concept Roundabouts with Signal Design Procedure The Proposed Approach Analysis Results Discussions 12

AIM OF THE STUDY To discuss the problem of signal timing assignment for signalized roundabouts. To propose a signal timing procedure for staged controlled signalized roundabouts. By this way to reduce delays of vehicles. 13

CONCEPT The signal timing assignment were studied by observing at signalized roundabouts of Turkey. A signal timing formula for storage area of central island was proposed. The formula is tested considering different cases. The VISSIM software was used for validation search of the proposed formula. The obtained results were compared. 14

ROUNDABOUTS 15

ADVANTAGES OF ROUNDABOUTS Reduce number of conflicts, improve traffic safety Increase Capacity Reduce vehicle delays Less expensive for operation cost Less space requirements (based on the location and application) 16

DISADVANTAGES It is not suitable for busy city networks It is not suitable for unbalanced demand cases. Annoys drivers who just want to bypass 17

TRAFFIC SIGNAL APPLICATIONS ON ROUNDABOUTS Federal Highway Administration s roundabout informational guide (7) states roundabouts should never be planned for metering or signalization. However, the guide does concede that unexpected demand may require signalization after a roundabout is constructed. The FHWA guide goes on to describe three signalization alternatives to be considered should unexpected demand suggest the need for signals: (1) metering, (2) nearby pedestrian signals, and (3) full signalization of the circulatory roadway. 18

ROUNDABOUT METERING It is applied for unbalanced flow patterns and high demand cases It has been used to create gaps in the circulating flow By this way excessive queueing and delays can be prevented It is first used in Australia. The pictures are from an application in Australia. 19

FULLY MOUNTED SIGNALS North Approach West Approach South Approach 38 m Width of a circulation lane: 4 m East Approach Width of an approach lane: 3.5 m Integration of signalized intersection and roundabout All arms and circulation area have signals Two cases: Increase in demand and Violation of traffic rules 20

SAMPLE FROM DENIZLI, TURKEY 21

SOFTWARES FOR MODELLING ROUNDABOUTS 22

SOFTWARES FOR MODELLING ROUNDABOUTS SIDRA FOR ROUNDABOUTS SIDRA is originally from Australia, developed by Dr. Rahmi AKCELIK. SIDRA INTERSECTION is the most popular software for roundabouts (multi-lane and single-lane) and other intersections in the USA and Canada, Australia and New Zealand, South Africa, Malaysia, and many countries in Europe, Arabian Peninsula, South America and elsewhere around the world. Roundabouts Roundabout Metering 23

LITERATURE Akcelik (2005, 2006), Natalizio (2005) -Roundabout Metering Brabender and Vereeck (2007), Qian et al (2008),- Safety and capacity issues Bai et al. (2010)- Effects of cycle time and diameters on vehicle delay Tracz and Choudr (2012)-Different Type of Phase Plan Maher (2008), Ma et al. (2013), Gokce et al. (2015) -Signal Timing Optimization Cheng et al. (2016)- A new model proposal for capacity calculation of Sign. Roundabouts 24

PROBLEM DEFINITION The problem considered in this research is observed at roundabouts that have storage areas around the central island and controlled by signalization. The reasons : improper design of storage area that is not sufficient for left turning traffic volumes signal timings. If signal timings are designed without sufficient observations of left turning volumes,; the storage area in the central island of roundabout may be blocked by left turning flow the conflicting flows (such as through flow from other direction) may not be moved until a clearance time for left turning flow or to switch next phase. This case cause some additional delays of vehicles. To handle this problem; geometric design control system design 25

DESIGN OF SIGNALIZED ROUNDABOUTS Movements are controlled by Two phase, Three phase, Four Phase. In Determination of Phase Plans Left turning flows, Pedestrians, Traffic composition (heavy vehicle rates) 26

Design Parameters Geometric condition of intersection Traffic volume Left turning rate Storage area of central island for left turning vehicles Signal timing for all vehicles Phase Sequence 27

GEOMETRIC CONDITIONS (DESIGN) OF INTERSECTION Geometric conditions of intersection have a considerable effects on design. The geometric elements (or components) of intersection (such as turning radius, lane width, radius of central island etc.) should meet the required standards. The design of intersection may have some faults in use of non-standardized elements. On the other hand, the intersection may serve under- capacity because of these design faults. 28

Storage Area of Central Island for Left turning vehicles The storage area of central island for left turning vehicles should have some specifications. The number of circulation lane, Dimensions of circulation lanes The designer should care about these elements and collect the required data from field. the left turning traffic volumes and heavy vehicle rates the variations of traffic volumes 29

Sample roundabout from Denizli, Turkey 30

Traffic Volumes of Left Turning vehicles Left turning traffic volumes have some considerable effects on design of signalized roundabouts. The number of vehicles and Traffic composition should be observed for a proper design. The rate of heavy vehicles for left turning traffic volumes 31

SIGNAL TIMING The proper signal timing design has a great importance on intersection control system performance. There is no specific software or design guide for signalized roundabouts. 32

Design Stages 1. Design the signal timings regarding traffic volumes on the approaches 2. Determine the cycle time and green times for the flows on the approaches 3. Calculate the number of cycles in an hour 4. Divide the biggest left turning volumes to the number of cycles for each phase. 5. Determine the number of lanes in the circulation area and divide the number obtained in step 4 to the number of lanes. 6. Calculate the departing times of vehicles in the circulation area (lanes) 7. Calculate the green time for central island 8. Add the green time for central island to the cycle time. 33

Signal Timing Formula for Central Island of Roundabout Φ = α + n 1 λ + ε Where; Φ : green time of central island (sec), α : the lost times of departing vehicles in queue (sec), n : the number of lines in storage area, λ : departing headways of vehicles (sec), ε : calibration coefficient for signal timing 34

C = 1.5L + 5 1 Y Φ = α + n 1 λ + ε C new = C + Φ n = q L (n c n SL ) ε = q L t Cadd n SL 2 t Cadd = [ 3600 C new C Φ : green time of central island (sec), α : the lost times of departing vehicles in the storage area (sec), n : the number of lines in storage area, λ : departing headways of vehicles (sec), ε : calibration coefficient for signal timing q L : left turning traffic volume (vph), n c : the number of cycle in an hour (n c = 3600/C), n SL : the number of lane in the storage area t cadd represents an additional timing that occurs an increase of cycle time 35

THE PROPOSED APPROACH 36

SCENARIOS Scenario I: In the first scenario, the traffic volumes are regarded with the existing signal timings and phase sequencing (four phase) for the intersection Scenario II: In the second scenario, the same phase sequencing (four phase) is used with signal timings obtained by the proposed formula. Scenario III: The third scenario includes three phased management and existing cycle times. Scenario IV: Three phased management and the signal timings optimized by the SIDRA is used in the last (fourth) scenario. 37

SCENARIOS Base traffic volumes are observed from the field. Based on this volumes, some experimental study is made. The traffic volumes in the E-W directions are increased and decreased by regarding different rates. (between 0% and 50%) The left turning flow rates are also varied between the ranges of 10% and 60 %. Two and three circulation lanes are taken into consideration. 38

TRAFFIC VOLUMES Movement Type O-D Directions Low Demand (base values) Car (vph) Heavy Veh. (vph) Total (vph) High Demand (base values) Car (vph) Heavy Veh. (vph) Total (vph) W-E 848 105 953 1015 101 1116 Through E-W 994 86 1080 1293 82 1375 N-S 182 20 202 231 10 241 S-N 86 4 90 90 3 93 W-E 11 0 11 20 0 20 Right Turn E-W 66 4 70 157 18 175 N-S 49 0 49 45 2 47 S-N 35 0 35 41 1 42 W-E 86 21 107 101 25 126 Left Turn E-W 102 26 128 138 34 172 N-S 22 6 28 26 6 32 S-N 11 3 14 12 3 15 Total (vph) 2493 274 2767 3169 285 3454 Sampl e No Approach Direction Variation Rate in Traffic Volume (%) 1 E - W 50 % Decreased Left Turning Rate (%) Sampl e No Approach Direction Variation Rate in Traffic Volume (%) Left Turning Rate (%) 10 29 E - W N/A 50 N - S N/A 10 N - S N/A 10 7 E - W 50 % Decreased 40 34 E - W 25 % Increased 20 N - S N/A 10 N - S N/A 60 12 E - W 25 % Decreased 10 37 E - W 25 % Increased 40 N - S N/A 60 N - S N/A 10 15 E - W 25 % Decreased 30 42 E - W 50 % Increased 10 N - S N/A 10 N - S N/A 60 19 E - W 25 % Decreased 50 47 E - W 50 % Increased 40 N - S N/A 10 N - S N/A 10 24 E - W N/A 20 50 E - W 50 % Increased 50 N - S N/A 60 N - S N/A 60 39

MOVEMENT NUMBERS AND PHASE SEQUENCE 7 8 9 1 2 3 13 14 4 5 6 12 11 10 40

CYCLE DIAGRAM 1 35 5 2 10 4 78 4 2 2 3 4 5 6 7 8 9 10 11 12 13 14 Cycle Diagram of Sample Case 1- Existing signal timings 41

SAMPLE CASES Number of Storage area lanes (lane) Total Traffic Volume (veh/hour) East Approach West Approach North Approach South Approach Sample Cases A.V.-L.T.V* A.V.-L.T.V* A.V.-L.T.V* A.V.-L.T.V* (veh/hour) (veh/hour) (veh/hour) (veh/hour) 1 2 2180 959-383 803-321 279-28 139-14 2 2 3354 1598-320 1339-268 279-28 139-14 3 2 3354 1598-320 1339-268 279-167 139-83 4 2 3942 1917-192 1607-161 279-167 139-83 5 2 1962 861-431 631-316 320-32 150-15 6 2 2708 1292-387 947-284 320-32 150-15 7 2 2708 1292-387 947-284 320-192 150-90 8 2 4200 2153-215 1578-158 320-32 150-15 9 2 4946 2583-258 1893-189 320-32 150-15 10 2 2180 959-383 803-321 279-167 139-83 11 2 2180 959-479 803-402 279-28 139-14 12 2 2180 959-479 803-402 279-167 139-83 13 2 2767 1278-383 1071-321 279-28 139-14 14 2 2767 1278-383 1071-321 279-167 139-83 15 2 3942 1917-192 1607-161 279-28 139-14 16 2 1962 861-431 631-316 320-192 150-90 17 2 3454 1722-344 1262-252 320-32 150-15 18 2 3454 1722-344 1262-252 320-192 150-90 19 2 4200 2153-215 1578-158 320-192 150-90 20 3 2180 959-383 803-321 279-167 139-83 21 3 2767 1278-383 1071-321 279-28 139-14 22 3 3354 1598-320 1339-268 279-167 139-83 23 3 3942 1917-192 1607-161 279-167 139-83 24 3 1962 861-431 631-316 320-32 150-15 25 3 2708 1292-387 947-284 320-192 150-90 26 3 3454 1722-344 1262-252 320-192 150-90 27 3 4946 2583-258 1893-189 320-32 150-15 28 3 4946 2583-258 1893-189 320-192 150-90 29 3 2180 959-479 803-402 279-28 139-14 30 3 2767 1278-383 1071-321 279-167 139-83 31 3 2708 1292-387 947-284 320-32 150-15 *A.V.: Approach Volume L.T.V.: Left Turning Volume 42

West East Green Timing: 40 50 Storage Area Green Timing: 74 North Green Timing: 20 South Green Timing: 23 Sample Cases Existing Signal Timings (sec) West East Green Timing (sec) Storage Area Green Timing (sec) North Green Timing (sec) South Green Timing (sec) Existing Improved Existing Improved RESULTS Improved Signal Timings (sec) Cycle Times (sec) Average Vehicle Delay (sec/veh) 1 17 21 53 12 8 140 90 * 51.54 2 43 52 57 15 9 140 125 143.03 111.44 3 43 52 62 18 11 140 130 * 116.66 4 46 54 55 16 11 140 125 136.64 55.96 5 14 19 50 12 9 140 85 154.48 47.72 6 25 32 52 12 8 140 100 151.57 72.27 7 23 30 59 16 11 140 105 * 116.91 8 42 57 52 13 8 140 125 129.81 77.07 9 43 58 51 11 8 140 125 146.07 112.92 10 18 22 57 15 9 140 95 * 55.48 11 18 22 57 12 8 140 95 * 84.68 12 18 23 61 15 9 140 100 * 118.17 13 26 30 54 13 8 140 100 * 101.64 14 29 33 56 14 9 140 105 * 107.91 15 48 56 48 12 8 140 120 133.36 47.12 16 14 19 55 14 10 140 90 * 51.42 17 40 50 59 15 9 140 125 124.57 110.64 18 41 51 63 17 11 140 130 * 117.01 19 41 55 59 17 11 140 130 135.83 101.22 20 18 22 52 13 9 140 90 140.38 71.40 21 33 37 52 12 9 140 105 132.51 98.56 22 47 55 59 16 11 140 130 120.31 102.35 23 45 54 55 16 11 140 125 124.38 81.73 24 16 20 49 10 8 140 85 165.51 76.49 25 25 32 57 15 11 140 105 141.19 114.78 26 39 47 57 15 11 140 120 126.51 102.96 27 45 60 54 14 9 140 130 145.88 88.87 28 46 61 58 16 11 140 135 150.13 109.45 29 21 25 49 10 8 140 90 226.25 119.70 30 33 37 57 15 11 140 110 136.37 114.41 31 25 33 51 12 8 140 100 136.59 110.55 *: Average vehicle delay > 250 sec/veh All red time: 4+4=8 sec Yellow time: 2+2=4 sec (at the start and end of the each phase) 43

COMPARISONS - GREEN AND CYCLE TIMES 74 sec-existing 140 sec-existing 44

COMPARISONS- VEHICLE DELAYS 45

COMPARISONS- DEGREE OF SATURATION 46

SIMULATIONS BEFORE AFTER 47

SIMULATIONS CASE I- 300TH SEC. BEFORE AFTER 48

SIMULATIONS CASE I- 700TH SEC. BEFORE AFTER 49

SIMULATIONS CASE I- 850TH SEC. BEFORE AFTER 50

COMPARISONS OF SCENARIOS The numbers shows the cases that have delay values that are less than 120 sec/veh 51

RESULTS A signal timing design proposal The central island of roundabouts Circulating traffic flows Aims To reduce vehicle delays, To make some discussions on design procedure. 52

RESULTS The formula proposed deals with the circulating flows staged phase sequencing (i.e. storage and circulated) Validation gives some encouraging results. The results showed that design of the storage area of central island is critical. 53

RESULTS Driver behaviors Traffic composition (esp. heavy vehicle rates) Simulations show that about 36% (average) decrease in vehicle delays may be obtained only using the proposed formula. Besides to delay the LOS may also be increased for the intersection. Cycle times may be improved in the same manner 54

DISCUSSIONS Validation of the formula may be expanded including some extreme cases including different geometries. Phase arrangements without regarding traffic volumes (like TranSync) may be searched. 55

ACKNOWLEDGEMENT This research is supported by the Scientific Research Project Department of Pamukkale University and the Scientific and Technical Research Council of Turkey (TUBITAK) while he was at University of Nevada, Reno as a visiting scholar. These supports are appreciated. 56

REFERENCES Akcelik, R. (2005) Capacity and Performance Analysis of Roundabout Metering Signals, TRB National Roundabout Conference, Vail-Colorado. Akcelik, R. (2006) Operating Cost, Fuel Consumption and Pollutant Emission Savings at a Roundabout with Metering Signals, 7 th International Congress on Advances in Civil Engineering (ACE 2006), İstanbul-Turkey. Bai, Y., Chen, W., Xue, K. (2010) Association of Signal-Controlled Method at Roundabout and Delay, 2010 International Conference on Intelligent Computation Technology and Automation, 1, Changsha, IEEE, 816-820. Brabender, B. D., Vereeck, L. (2007) Safety Effects of Roundabouts in Flanders: Signal Type, Speed Limits and Vulnerable Road Users, Accident Analysis & Prevention, 39 (3), 591-599. Cakici, Z. (2014) The Investigation of Design Principles of Signalized Roundabouts, MSc Thesis, Pamukkale University, Institute of Natural and Applied Sciences, Denizli, Turkey, 207 p. Cheng, W., Zhu, X., Song, X. (2016) Research on Capacity Model for Large Signalized Roundabouts, Procedia Engineering, 137, 352-361. Coelho, M. C., Farias, T. L., Rouphail, N. M. (2006) Effect of Roundabout Operations on Pollutant Emissions, Transportation Research Part D: Transport and Environment, 11 (5), 333-343. Gardziejczyk, W., Motylewicz, M. (2016) Noise Level in the Vicinity of Signalized Roundabouts, Transportation Research Part D: Transport and Environment, 46, 128-144. Gokce, M. A., Oner, E., Isık, G. (2015) Traffic Signal Optimization with Particle Swarm Optimization for Signalized Roundabouts, Simulation: Transactions of the Society for Modeling and Simulation International, 91 (5), 456-466. Gross, F., Lyon, C., Persaud, B., Srinivasan, R. (2013) Safety Effectiveness of Converting Signalized Intersections to Roundabouts, Accident Analysis & Prevention, 50, 234-241. 57

REFERENCES Johnnie, B. E., Ahmed, A., Iman, A. (2012) Extent of Delay and Level of Service at Signalized Roundabout, International Journal of Engineering & Technology, 2 (3), 419-424. Ma, W., Liu, Y., Head, L., Yang, X. (2013) Integrated Optimization of Lane Markings and Timings for Signalized Roundabouts, Transportation Research Part C: Emerging Technologies, 36, 307-323. Maher, M. (2008) The Optimization of Signal Settings on a Signalized Roundabout Using the Cross-Entropy Method, Computer-Aided Civil and Infrastructure Engineering, 23 (2), 76-85. Mandavilli, S., Rys, M. J., Russell, E. R. (2008) Environmental Impact of Modern Roundabouts, International Journal of Industrial Ergonomics, 38 (2), 135-142. Natalizio, E. (2006) Roundabouts with Metering Signals, Institute of Transportation Engineers 2005 Annual Meeting, Melbourne-Australia. Otkovıc, I. I., Dadıc, I. (2009) Comparison of Delays at Signal-Controlled Intersection and Roundabout, Promet Traffic & Transportation, 21 (3), 157-165. Qian, H., Li, K., Sun, J. (2008) The Development and Enlightenment of Signalized Roundabout, 2008 International Conference on Intelligent Computation Technology and Automation, 2, Hunan, IEEE, 538-542. Sisiopiku, V., Oh, H. (2001) Evaluation of Roundabout Performance Using Sidra, Journal of Transportation Engineering, 127 (2), 143-150. Tracz, M., Chodur, J. (2012) Performance and Safety of Roundabouts with Traffic Signals, SIIV-5 th International Congress - Sustainability of Road Infrastructures (Procedia - Social and Behavioral Sciences), 53, 788-799. Yang, X., Li, X., Xue, K. (2004) A New Traffic-Signal Control for Modern Roundabouts: Method and Application, IEEE Transactions on Intelligent Transportation Systems, 5 (4), 282-287. 58

THANKS FOR YOUR PARTICIPATIONS AND PATIENTS Dr. Yetis Sazi MURAT Pamukkale University Faculty of Engineering Civil Eng. Dept. 20070 Denizli/TURKEY E-mail: ysmurat@pau.edu.tr sazimurat@gmail.com http://www.pau.edu.tr/ysmurat/en 59