Different approaches to minimum delay prediction at single-lane traffic circles in İzmir, Turkey

A New Minimum Delay Model for Multi-Lane Traffic Circles

“…where D mini is the delay for the i th maneuver (seconds); Q i is the conflict flow in front of the minor stream approach i th maneuver (veh/hr) and R, L and TH expressions denote right turning, left turning and through passing maneuvers respectively. While Kyte et al [18] and Al-Omari and Benekhoal [19] have suggested linear functions, Chandra et al [30] have used an exponential function for estimating minimum delay: (18) A similar approach for single lane traffic circles has also been tested by Tanyel et al [7], where they also showed that a power function can be an adequate alternative for minimum delay estimation. Çelik [31] also suggested an exponential equation, which is derived by using the outputs of a simulation program he developed: (19) Ashalata and Chandra [32], by using simulation technique, tried to model minimum delay at unsignalized intersections for different priority movements under varying composition of conflicting traffic.…”

“…From this point of view, it can be said that minimum delay is also highly depends on geometric properties of an intersection. Thus Tanyel et al [7] have developed the following empirical function, which defines the effect of geometric parameters on minimum delay at single-lane traffic circles: (20) where D i is the inscribed diameter of traffic circle (m), w ent is the entry lane width of the minor approach (m) and  is the conflict angle.…”

“…From above, it is clear that minimum delay (D min ) mainly depends on the platooning characteristics in the major stream [10], critical gap and follow-up times of vehicles in the minor stream and geometric characteristics of an intersection [7]. However, number of entering vehicles from minor approach may also be an important parameter in estimating minimum delay as it depends on the same parameters.…”

“…where T 0 is follow-up time for minor-stream drivers (seconds). Tanyel et al [7] have also investigated the effect of entering vehicles on minimum delay. They used the function suggested by Horton [36] for infiltration capacity, which can be written in general form for minimum delay as: (23) where D minup is the upper limit of minimum delay (sec), D minlow is the lower limit of minimum delay (sec) and K is a constant.…”

“…Çelikoğlu [6]. However only a limited number of studies like Tanyel et al [7] have been conducted on performance of traffic circles.…”