Analysis of Kinematic Parameters and Driver Behavior at Turbo Roundabouts

Abstract

This study focuses on both vehicle kinematic parameters (speed and acceleration) and behavior parameters (critical interval and follow-up time) of drivers at turbo-roundabouts. Empirical evaluations of such parameters can be helpful in calibrating traffic microsimulation models or assigning behavior parameters to closed-form capacity models in turbo-roundabouts (gap-acceptance capacity models) and are also related to evaluation of vehicles pollutant emissions. The research was based on traffic process observed in the first turbo-roundabout implemented in the city of Maribor in Slovenia. In 216 a great number of traffic samples were taken with high-frame-rate video recordings [>5 frames per second (fps)]. All vehicle trajectories were obtained with the methods and algorithms typical of the digital imageprocessing technique (DIP) by filtering the discrete signal of vehicle trajectories f(t)i with wavelet analysis. The research results showed that vehicle speeds on entry lanes are rather moderate (below 25 km/h, 15 m prior to the Yield line), whereas accelerations usually have values inferior to 2 m/s2 on arm lanes and to 1.5 m/s2 on ring lanes. The critical intervals tc [distributed according to an Erlang probability distribution function (PDF)] and follow-up headways tf (distributed according to an inverse Gaussian PDF) have, on the other hand, values in ranges of tc=4.3–5.48 s and tf=2.52–2.71 s, respectively, according to the right- or left-turn lane and to the major or minor entry in question.