Assessing Consistency of PCE Values on HCM 2010 For Selected Multilane Highways of Addis Ababa, Ethiopia
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Date
2023-10
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Addis Ababa University
Abstract
Passenger Car Equivalents (PCE) plays a crucial role in road design and traffic management by converting the impact of various vehicle categories on a traffic stream into a standardized equivalent passenger car. Their utilization is essential in a heterogeneous vehicle composition in road traffic. Hence, main objective of this research is to assess the consistency of PCE values in the Highway Capacity Manual (HCM, 2010) for local multilane highways. To achieve the stated objective, three key parameters were considered. Firstly, the assumptions made in HCM 2010 were comprehensively reviewed and compared with the actual local conditions. Secondly, existing relevant literature was surveyed to gather insights from other similar studies. Lastly, data was collected from the Outer Ring Road, a selected multilane highway in Addis Ababa and local PCE values were determined using the flow rate and density method, the speed area method, and simulation with Planung Transport Verkehr AG Verkehr In Städten – Simulations Modell version 9 (PTV VISSIM).The analysis revealed that the direct use of PCE values presented in HCM 2010 is inconsistent with the local conditions. Consequently, the study proposes different PCE values for various vehicle categories and heavy vehicles in general, taking into account the road's percent grade and the proportion of heavy vehicles in the traffic stream. The findings show that, proposed PCE values significantly deviate from those in HCM 2010 due to the variations observed in the local condition. In conclusion, this study underscores the inconsistency of directly applying PCE values from HCM 2010 in road design and traffic management projects. Accordingly, using small values of PCE leads to underestimating traffic volume, underestimating traffic impact, designing inefficient road pavements, and inaccurately analyzing and estimating costs. Hence, the studyadvocates for the use of local PCE values derived from researches which consider the specific
local conditions.
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Keywords
Passenger Car Equivalents, Multilane Highway, Heavy Vehicles, HCM 2010