Merging process of U-turns at uncontrolled median openings under mixed traffic conditions
At an uncontrolled median opening, the limited priority situation and the high degree of heterogeneity in traffic stream make the merging manoeuvre of U-turning vehicles very much complex. This study is an attempt to understand this merging manoeuvre. The different types of merging manoeuvres have been identified in the field and accordingly classified into different categories. Depending upon the number of vehicles that can merge all together into the opposing through traffic by accepting a single gap, the merging has been classified into two types: single entry merging and multiple entry merging. On the other hand, based on the situation of priority of movement, the merging process is divided into another two categories: ideal merging and forced merging. More explicitly, the ideal merging is split into free merging and Swift Merging (SM). In addition, the forced entry merging is categorized into Gradual Merging (GM) and Aggressive Merging (AM). Time distance diagrams for different types of merging are presented for their better understanding. Field data collected at seven median openings located on various 6-lane divided urban roads are used to analyse different types of merging in a mixed traffic situation. All vehicles plying on the road are divided into 5 categories such as car, motorized two-wheeler (2-W), motorized three-wheeler (3-W), Sports Utility Vehicle (SUV), and Light Commercial Vehicle (LCV) and the merging behaviour of these categories of vehicles have been studied. The effect of influencing parameters like opposing traffic volume and delay on merging are investigated. Mathematical relations are developed between Merging Time (MT) of a vehicle type and the opposing traffic volume. To address the effect of Service Delay (SD) on the MT of a vehicle, models are proposed between SD and MT for all the five categories of vehicles. The two types of merging; gradual and swift are prominently observed in field. The time required by different categories of vehicles for these two merging at various traffic volume levels are determined. Finally, two-tailed t-test is conducted to see if the MT for the two different types of merging is statistically different.
Aldian, A.; Taylor, M. A. P. 2001. Selecting priority junction traffic models to determine U-turn capacity at median opening, Proceedings of the Eastern Asia Society for Transportation Studies 3(2): 101–114.
Al-Omari, B. H.; Benekohal, R. F. 1997. Delay at congested unsignalized intersections, in Traffic Congestion and Traffic Safety in the 21st Century: Challenges, Innovations, and Opportunities, 8–11 June 1997, Chicago, Illinois, 194–200.
Autey, J.; Sayed, T.; El Esawey, M. 2013. Operational performance comparison of four unconventional intersection designs using micro-simulation, Journal of Advanced Transportation 47(5): 536–552. http://doi.org/10.1002/atr.181
Chu, T. D.; Nakamura, H.; Chen, P.; Asano, M. 2013. Quantifying effects of acceleration lane lengths and traffic conditions on merging maneuvers at urban expressway entrances, Proceedings of the Eastern Asia Society for Transportation Studies 9: 1–13.
Chu, T. D.; Miwa, T.; Morikawa, T. 2014. An analysis of merging maneuvers at urban expressway merging sections, Procedia – Social and Behavioral Sciences 138: 105–115. http://doi.org/10.1016/j.sbspro.2014.07.186
Dey, P. P.; Nandal, S.; Kalyan, R. 2013. Queue discharge characteristics at signalised intersections under mixed traffic conditions, European Transport – Trasporti Europei 55: 1–21.
Drew, D. R. 1968. Traffic Flow Theory and Control. McGraw-Hill Inc. 467 p.
Esawey, M.; Sayed, T. 2007. Comparison of two unconventional intersection schemes: crossover displaced left-turn and upstream signalized crossover intersections, Transportation Research Record: Journal of the Transportation Research Board 2023: 10–19. http://doi.org/10.3141/2023-02
Esawey, M. E.; Sayed, T. 2013. Analysis of unconventional arterial intersection designs (UAIDs): state-of-the-art methodologies and future research directions, Transportmetrica A: Transport Science 9(10): 860–895. http://doi.org/10.1080/18128602.2012.672344
Kanagaraj, V.; Srinivasan, K.; Sivanandan, R. 2010. Modeling vehicular merging behavior under heterogeneous traffic conditions, Transportation Research Record: Journal of the Transportation Research Board 2188: 140–147. http://doi.org/10.3141/2188-1
Kondyli, A.; Elefteriadou, L. 2012. Driver behavior at freeway-ramp merging areas based on instrumented vehicle observations, Transportation Letters 4(3): 129–142. http://doi.org/10.3328/TL.2012.04.03.129-141
Kyte, M.; Clemow, C.; Mahfood, N.; Lall, B. K.; Khisty, C. J. 1991. Capacity and delay characteristics of two-way stop-controlled intersections, Transportation Research Record: Journal of the Transportation Research Board 1320: 160–167.
Marczak, F.; Daamen, W.; Buisson, C. 2013. Key variables of merging behaviour: empirical comparison between two sites and assessment of gap acceptance theory, Procedia – Social and Behavioral Sciences 80: 678–697. http://doi.org/10.1016/j.sbspro.2013.05.036
Meng, Q.; Weng, J. 2012. Classification and regression tree approach for predicting drivers’ merging behavior in short-term work zone merging areas, Journal of Transportation Engineering 138(8): 1062–1070. http://doi.org/10.1061/(ASCE)TE.1943-5436.0000412
Milanes, V.; Godoy, J. Villagra, J.; Perez, J. 2011. Automated on-ramp merging system for congested traffic situations, IEEE Transactions on Intelligent Transportation Systems 12(2): 500–508. http://doi.org/10.1109/TITS.2010.2096812
Obaidat, T. A.; Elayan, M. S. 2013. Gap acceptance behavior at U-turn median openings: Case study in Jordan, Jordan Journal of Civil Engineering 7(3): 332–341.
Oh, S.; Yeo, H. 2012. Microscopic analysis on the causal factors of capacity drop in highway merging sections, in TRB 91st Annual Meeting Compendium of Papers DVD, 22–26 January 2012, Washington, DC, US, 1–23.
Richl, L.; Sayed, T. 2006. Evaluating the safety risk of narrow medians using reliability analysis, Journal of Transportation Engineering 132(5): 366–375. http://doi.org/10.1061/(ASCE)0733-947X(2006)132:5(366)
Riener, A.; Zia, K.; Ferscha, A.; Ruiz Beltran, C. R.; Minguez Rubio, J. J. M. 2013. Traffic flow harmonization in expressway merging, Personal and Ubiquitous Computing 17(3): 519–532. http://doi.org/10.1007/s00779-012-0505-6
Tageldin, A.; Sayed, T.; Shaaban, K.; Zaki, M. H. 2015. Automated Analysis and Validation of Right-Turn Merging Behavior, Journal of Transportation Safety & Security 7(2): 138–152. http://doi.org/10.1080/19439962.2014.942019
Tian, Z. Z.; Troutbeck, R.; Kyte, M.; Brilon, W.; Vandehey, M.; Kittelson, W.; Robinson, B. 2000. A further investigation on critical gap and follow-up time, in Transportation Research Circular E-C018: 4th International Symposium on Highway Capacity, 27 June – 1 July 2000, Maui, Hawaii, 397–408.
TRB. 2004. Safety of U-Turns at Unsignalized Median Openings. TRB’s National Cooperative Highway Research Program (NCHRP) Report 524. Transportation Research Board (TRB), Washington, DC. 141 p. http://doi.org/10.17226/13768
Weng, J.; Meng, Q. 2011. Modeling speed-flow relationship and merging behavior in work zone merging areas, Transportation Research Part C: Emerging Technologies 19(6): 985–996. http://doi.org/10.1016/j.trc.2011.05.001