Microscopic Traffic Flow Parameters Analysis for Highways and Motorways

Abstract

On a microscopic level, Time headway is the temporal distance between two consecutive vehicles, and speed is frequently employed as a qualitative service indicator. Time headway and speed are critical for traffic modeling because they provide a complete picture of the aggregate flow of vehicles and can inherently define the features of traffic flow. Previous research on this topic mainly focused on stochastic modeling of homogenous traffic following lane discipline. Few studies demonstrate weak-lane discipline heterogeneous traffic, considering the whole road section as a single lane. This research focuses on the theoretical modeling and statistical analysis of "Time headway and Speed" for heterogeneous data on slow and fast lanes. For analysis, a large amount of "Time headway and speed" data was collected using metrocount@5600 on NH-5 (site-1), NH-45 (site-2), and M-1 (site-3) in Pakistan. Site-1 and site-2 are four-lane median separated highways, and site-3 is a six-lane median separated motorway. Time headway analysis for mixed traffic and different leader-follower vehicle pairs and speed analysis for mixed traffic are examined with varying flow ranges starting from 0 to 1500 PCU/hr with an increment difference of 100 PCU/hr. Kolmogorov-Smirnov (K-S) test is used to check the statistical validity of each distribution. The results demonstrate that the speed and time headway follow distinct distribution patterns at various flows for each case. Similarly, speed data analysis for different sites' heterogeneous traffic and vehicle classes is also carried out on FL and SL to determine the influence of overall flow and vehicle mix on speed. These results can be used to perform capacity analysis, safety analysis, delay analysis, accident analysis, gap acceptance analysis, queue analysis, LOS analysis, etc. These outcomes will also assist in understanding driver behavior and developing microsimulation mode.