Limitations of Passenger-Car Equivalent Derivation for Traffic Streams with More Than One Truck Type

Demarchi, Samuel; Setti, José Reynaldo

doi:10.3141/1852-13

Cited by 54 publications

(28 citation statements)

References 4 publications

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“…Nevertheless, almost all PCE evaluation techniques tend to be based on one type of traffic flow variable or another. While most PCE estimation approaches use headways [1,[8][9][10], others are based on speeds [11], delay [12][13][14], density [5,15], travel time [16] and even platoon formation [11]. Whichever approach is used, the outcome shouldreflect prevailing local conditions and the character of local traffic.…”

Section: Introductionmentioning

confidence: 99%

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

Obiri-Yeboah¹

2014

IOSRJEN

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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.

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Section: Introductionmentioning

confidence: 99%

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

Obiri-Yeboah¹

2014

IOSRJEN

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“…For multiple types of vehicles, a revision of Huber's method by Demarchi and Setti (27) was also adapted. The performance measure employed for flow equivalency computation was total travel time.…”

Section: Methodsmentioning

confidence: 99%

Developing Standard Pedestrian-Equivalent Factors

Galiza

Ferreira

2012

Transportation Research Record: Journal of the Transportation R

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groups (7-11). The last category deals with how people form groups while walking and the proportions of these groups. This paper deals with different pedestrian types segregated according to well-established pedestrian categories (e.g., commuters, older adults), although focus is more on how they are handled in design. It has been established that the introduction of other pedestrian types (e.g., older adults) in commuter-only traffic shifts the level of service (LOS) in the design guidelines (12, 13) such that assumed LOS might not represent the actual pedestrian experience within the facility. Contemporary analysis of pedestrian capacity has yet to mature to account implicitly for the effect of the heterogeneity in pedestrian traffic, although some form of adjustment factor has been suggested. Only a few studies have recommended a means for considering diversity in the design of pedestrian facilities (14-17). Nevertheless, no consensus or standard procedure for tackling pedestrian diversity has been proposed. This paper introduces the concept of standard pedestrian-equivalent (SPE) factors, with the aim of presenting a standard methodology. This paper is organized as follows. The next section briefly discusses the research objectives. Past work on PCE estimation and comparison of vehicle and pedestrian traffic and the details of the proposed SPE methodology are described in two sections that follow. The results of the sensitivity analysis and case study are then presented, and those are followed by an illustration of the application of this study. The paper ends with the presentation of relevant findings and recommendations for future investigations. ReseaRch ObjectivesThis paper introduces the concept of SPE factors with the aim of presenting a standard methodology for dealing with heterogeneity in pedestrian flow as the PCE methodology does in the HCM. The Transit Capacity and Quality of Service Manual (18) is the transit counterpart to HCM 2010 (19). The manual contains quantitative techniques for calculating passenger circulation, and LOS in transit stations or terminals are primarily founded on Fruin (20). This is the reason for using Fruin's data in this paper: to investigate the effects of operational and physical factors in the walkway design process. The manual recommends an adjustment factor to account for pedestrians who use additional space, although limited guidance on the factor to use is provided. This research has three specific objectives: (a) to evaluate PCE methodologies to be adapted for SPE estimation, (b) to test the methodology by varying pedestrian walking speed and body size inputs through microsimulation; and Vehicle traffic does not consist entirely of passenger cars but also recreational vehicles (RVs), buses, and trucks. To address the problem in capacity analysis, passenger car-equivalent (PCE) factors were introduced. Use of PCE started in the 1965 Highway Capacity Manual (HCM) with the purpose of converting heterogeneous vehicle flow into an equivalent passenger car flow (1). PC...

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“…In some countries, heterogeneity is predominantly due to the presence of truck traffic. Demarchi and Setti (2003) suggest that as more vehicle types with different PCEs are included in the traffic stream the error in the estimation of flow values increase with the increase in density per lane. TienPen, Sadullah and Dao (2003) discuss a collaborative study concept of expressing the heterogeneous traffic in terms of car equivalents if truck is considered as non-homogeneous was first proposed by St John (1976).…”

Section: Literature Reviewmentioning

confidence: 96%