Passenger Car Equivalents for Vehicles at Signalized Intersections within the Kumasi Metropolis in Ghana

Abstract

Abstract:-Passenger car equivalents (PCEs) used in Ghana have been adopted from other countries and, therefore, cannot be said to capture the impact of local conditions in signalized intersection analysis. In this study, passenger car equivalents were evaluated for three vehicle categories; cars, medium vehicles, and trucks, which use signalized intersections within the Kumasi Metropolis, Ghana. The objective was to develop PCEs which truly reflect the prevailing traffic mix, flow conditions and the effect of roadside friction at the intersections. Data was collected on discharge headways at eleven signalized intersections controlled by pretimed signals,and using the headway ratio method, PCEs of the three categories of vehicles were estimated. PCE values were higher at intersections with roadside friction than those at intersections devoid of such friction. In comparison, the values obtained from the study are larger than those adopted from elsewhere and probably reflect more accurately the impact of local conditions on discharge at the intersections. This underscores the need to develop PCEs appropriate to local conditions rather than adopt from other standards.

Delay-based Passenger Car Equivalent at Signalized Intersections in Iran

“…They found PCE values were higher at intersections with roadside friction than the ones without such friction. Obiri-Yeboah et al showed the PCE value at intersection in Kumasi was larger than the value prevalently used [13]. The results of all current studies supported the claim that the values of PCE are different for each country due to differences in driving behaviours, available transport facilities, and so on.…”

“…A similar study was done in Kumasi city, Ghana in 2014 [13]. In this study, Obiri-Yeboah et al analysed eleven pre-timed signalized intersections to assess the influence of roadside friction on the value of PCE.…”

“…In recent years, there have been several studies on estimating regional values of PCE. The current literature on regional PCE estimation abounds with examples of PCE at midblock locations [6,10,11] and PCE at intersections [12][13][14].…”

Area-Type Adjustment Factors for Non-CBD Signalised Intersections

“…This concept may be seen as re-echoing the recognition by Tarko and Tracz [8] that omission of some capacity factors in predictive models and inadequate functional relationship between model variables and saturation flow rates introduce certain level of errors for existing capacity analysis. The present study, which was an extension of previous studies [9,10] on signalized intersection flows within the Kumasi Metropolis, was aimed at developing area-type adjustment factors that reflect local conditions when the HCM model is to be used as the tool for the estimation of saturation flows.…”

“…Data associated with the gradients and geometrics at the intersections and other parameters required for computing all the relevant adjustment factors in the HCM model were collected manually. Passenger car equivalent values developed by Obiri-Yeboah et al [9] for signalized intersections within the metropolis (see Table 2) were used in computing the modified bus blockage factor suggested by Tuffour et al [10]. The bus blockage time (t b ) in Eq.…”