Meaning of actual capacity of freeways and its estimation

2010 ◽  
Vol 37 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Shy Bassan ◽  
Abishai Polus
Keyword(s):  
Curve Fitting ◽  
Flow Characteristics ◽  
Time Interval ◽  
Unstable Flow ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Freeway Capacity ◽  
Capacity Estimates ◽  
Equal Density

The flow on urban and suburban freeways is characterized typically by high densities, occupancies, and frequent breakdowns, particularly when the volume approaches capacity. This creates unstable flow conditions, resulting in recurrent as well as random congestion. The purpose of this study was twofold: (1) to develop models for evaluating flow characteristics on a busy suburban freeway, specifically speed versus flow and flow versus occupancy; (2) to understand the meaning of capacity by evaluating the actual capacity of a freeway section. The data were collected on Highway 1 in Israel and on Interstate 66 in Virginia, USA. Previous observations showed that both freeways operated at a saturated-flow condition almost daily and that breakdowns of the stream occurred often, though not daily. The paper presents a concept that suggests that freeway capacity is an actual-site specific term. This capacity can change frequently in space and time, depending on the section geometry, the time interval, the prevailing traffic and environmental conditions, and driving behavior. Determination of a representative value of actual capacity for level-of-service or planning analyses is suggested, based on one of three methods: parabolic curve-fitting for free-flow, dense congested stable (DCS) flow, and breakdown-flow data; the intersection of the best-fit stable-flow parabola and the equal-density adjusted line; and curve fitting of one-regime models to flow-occupancy data. Also included is a comparison with the 2000 Highway capacity manual (HCM) models and with capacity estimates from other studies. The results showed similar values of actual capacity estimates for the three methods.

Defining Freeway Design Capacity Based on Stochastic Observations

2018 ◽  
Vol 2672 (15) ◽  
pp. 131-141 ◽  
Author(s):  
Siavash Shojaat ◽  
Justin Geistefeldt ◽  
Scott A. Parr ◽  
Luis Escobar ◽  
Brian Wolshon
Keyword(s):  
Flow Index ◽  
Empirical Comparison ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
General Acceptance ◽  
Probability Of Survival ◽  
Speed Flow ◽  
Stochastic Capacity ◽  
Freeway Capacity ◽  
Capacity Estimates

The estimation of capacity as a parameter to assess traffic flow performance on freeway facilities has received considerable attention in the literature. Despite the general acceptance of the stochastic notion of capacity, limited research has been conducted on how to select a single representative design value from a capacity distribution function. This paper reports the results of an empirical comparison between conventional capacity estimates and those obtained by maximizing the sustained flow index (SFI) for 19 U.S. freeway sections. The SFI is defined as the product of the traffic volume and the probability of survival at this volume. The capacity of each cross-section was estimated by analyzing the speed–flow relationship and applying methods for stochastic capacity analysis. The results show that the optimum volumes obtained by maximizing the SFI estimated in 5-minute intervals correspond well to the 15% probability of breakdown proposed in the Highway Capacity Manual 6 th Edition to estimate the capacity from field data. From these results, it was concluded that maximizing the SFI can be considered a preferred approach to estimate a single, representative value of freeway capacity.

scholarly journals Evaluation passenger car unit for motorcycle in Indonesia Highway Capacity Manual (Case study: Bandung and Semarang)

2018 ◽  
Vol 181 ◽  
pp. 06006
Author(s):  
Najid
Keyword(s):  
Traffic Density ◽  
Heavy Vehicles ◽  
Highway Capacity ◽  
Passenger Car ◽  
Highway Capacity Manual ◽  
Traffic Conditions ◽  
A Value ◽  
Passenger Car Unit ◽  
Set Up

Value of Passenger Car Unit or commonly known as PCU value is a value that is given to any vehicle that is classified into heavy vehicles, light vehicles (passenger car) and motorcycles. The value of passenger car unit on Indonesia Highway Capacity Manual (IHCM) set up in 1997 is based on a study conducted from 1980-1990 in several cities in Indonesia At the time of the study, the traffic conditions are very different to the current traffic conditions. That affects of difference traffic conditions are the composition of traffic, traffic regulations, traffic density, traffic discipline and the presence of mass transit, so that the results of traffic analysis do not always correspond to reality as there are anomalies in the determination of the level of road service (Najid, 2014). As well the incompatibility of the capacity value which is considered due to the incompatibility value of Passenger Car Units (PCU). Evaluation PCU become very important to get the value of traffic parameters into compliance with actually occur. In accordance with the traffic density is higher actually, then it is necessary to study for evaluation against PCU current value and the need to approach or to get the value of PCU more in line with current traffic conditions. Data collected at two cities, those are Bandung and Semarang. Based on analysis found PCU’s value that got from survey have difference but not all significantly with PCU value in IHCM.

Determining the capacity of the Canadian trans-mountain highway system

1976 ◽  
Vol 3 (3) ◽  
pp. 355-371
Author(s):  
John F. Morrall ◽  
Neville Cameron ◽  
Al Werner
Keyword(s):  
Highway Capacity ◽  
Passenger Car ◽  
Highway Capacity Manual ◽  
Recreational Vehicles ◽  
Improper Use ◽  
Adjustment Factors ◽  
Highway Planning ◽  
Design Hourly Volume ◽  
Selection Of

Trans-mountain highway capacity is sensitive to the percentage of recreational vehicles in the traffic stream, the manner in which passenger car equivalents for recreational vehicles are used in capacity computations, terrain classification, and the choice of design hourly volume. The sensitivity of capacity to these factors is demonstrated for the trans-mountain portion of the Trans-Canada highway which is a two-lane highway, characterized in many locations by long steep grades. This particular highway has a high percentage of recreational vehicles during summer months. The Highway Capacity Manual does not make any provision for the effect of such vehicles and previous highway planning studies have used the adjustment factors for trucks and buses to estimate their effect. Neglecting the effect of recreational vehicles and/or improper use of their passenger car equivalents in capacity computations can result in serious errors in the determination of highway capacity especially in mountainous areas. Further research is required in the areas of terrain definition, selection of design hourly volume, and the present concept of level of service.

Freeway Weaving: Comparison of Highway Capacity Manual 2000 and Dutch Guidelines

2003 ◽  
Vol 1852 (1) ◽  
pp. 10-18 ◽  
Author(s):  
M. M. Minderhoud ◽  
L. Elefteriadou Elefteriadou
Keyword(s):  
United States ◽  
Sensitivity Analysis ◽  
The United States ◽  
Level Of Service ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Additional Variable ◽  
Different Types ◽  
The U.S ◽  
Capacity Estimates

Weaving sections are a commonly adopted freeway facility both in the United States and in Europe. Knowledge about the capacity and level of service achievable on different types of weaving segments is necessary for the design and management of freeways. Guidelines such as those of the U.S. Highway Capacity Manual (HCM) provide capacity values for different weaving configuration types. The Dutch guidelines for the design of weaving segments are compared with those of the U.S. HCM. Differences between their respective approaches are identified, and a comparison of capacity values is conducted. It was found that there are large differences in capacity estimates for certain weaving configuration types. The results of a sensitivity analysis explain these differences in capacity values to a large extent. This analysis showed that it is important to consider the weaving proportions per leg. Currently, neither the HCM nor the Dutch approach considers different weaving flows per incoming leg. The introduction of an additional variable into the calculation procedure that takes into account the presence of asymmetrical weaving flows is recommended.

scholarly journals Analysis of calculating level of service for pedestrians

2021 ◽  
Vol 2021 (1) ◽  
pp. 50-59
Author(s):  
Vsevolod Prykhodko ◽  
◽  
Ihor Vikovych ◽  
Keyword(s):  
Level Of Service ◽  
Signal Delay ◽  
Highway Capacity ◽  
Pedestrian Movement ◽  
Highway Capacity Manual ◽  
Road Users ◽  
Method Of Determination ◽  
Significant Probability ◽  
Main Factors

In this paper, several methods of the assessment of pedestrian objects operation based on the level of service are reviewed. Today, there is a problem that should be assessed, particularly how pedestrian paths respond the level of service. Assessment of this level is the most widespread method of determination the objects` quality that relate to the pedestrian operations. Places, where a significant probability of conflict between different flows and their users, are often called intersections. Moreover, on such intersections, particularly with complex road conditions and on which the movement of cyclists, cars, and different vehicles is present, road users face with complicated situations when every of them should be sure in his safety and forecast further actions and decisions of other road users. The most widespread and generally accepted methods of assessment of level of service on pedestrian path, particularly: Highway capacity manual 2000 method, Australian method, method of the trip quality, Landice model and common approach analysis. Vehicles, signal delay, and interaction of pedestrians and cyclists were determined as the main factors that have impact on the level of service of pedestrians at the intersections. Analysis of different methods in the paper allows assessing and identifying the level of service determining the characteristics that could help in solving the questions concerning the comfort of pedestrian movement. In the range of these methods, the principles of vehicles movement and interaction with pedestrians are also reviewed. Other methods relate more to the design of the objects of pedestrian environment than factual movement of pedestrians. To form the whole understanding of the methodology of determination of the level of service of pedestrian objects, we should analyze and compare the values, obtained by different methods.

scholarly journals Evaluation of the Quality of Service of Pedestrian Flows on a Signalized Intersections

2019 ◽  
Vol 65 (2) ◽  
pp. 37-42
Author(s):  
Vuk Bogdanović ◽  
Nemanja Garunović ◽  
Valentina Basarić ◽  
Jelena Mitrović Simić
Keyword(s):  
Quality Of Service ◽  
Signalized Intersections ◽  
Highway Capacity ◽  
Local Conditions ◽  
Highway Capacity Manual ◽  
Traffic Conditions ◽  
Novi Sad ◽  
First Time

In 5th edition of Highway Capacity Manual (2010) the methodology for evaluating the quality of service provided to pedestrians traveling through a signalized intersection first time was shown. The same methodology has been retained in the latest edition of the aforementioned manual. Provided methodology include determination of the key parameters for evaluation the quality of service of pedestrian flows on signalized intersections. In this paper mentioned methodology was shown through the short procedural steps. In order to verify the possibility of applying this procedure in local conditions, an analysis of traffic conditions at an intersection in Novi Sad was performed as an example.

scholarly journals Perubahan Nilai Ekivalensi Mobil Penumpang Akibat Perubahan Karakteristik Operasional Kendaraan di Jalan Kota Semarang

2017 ◽  
Vol 23 (1) ◽  
pp. 69
Author(s):  
EPF. Eko Yulipriyono ◽  
Djoko Purwanto
Keyword(s):  
Heavy Vehicles ◽  
Passenger Cars ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
The Road ◽  
Road Section ◽  
Operational Characteristics ◽  
Passenger Car Equivalent ◽  
On The Road

Passenger Car Equivalent (PCE) is a conversion factor to make equal the various types of vehicles that operating on the road section into one type of vehicles i.e. passenger cars. Indonesian Highway Capacity Manual (MKJI) 1997 has set the PCE values for various types of vehicle groups either motorized. PCE values of various types of vehicles are not absolute because many factors that affect can change over time and development of automotive technology. This study aimed to find out the changes of PCE value that occurs. As for the purpose of research to determine the current number of PCE values due to the change of operational characteristics of vehicles on a highway especially for urban highways. Data analysis for the determination of PCE values used: time headway method, speed method, capacity method, and vehicle dimension method. The conclusion of this study: PCE of light vehicles (LV) = 1 still in accordance with MJKI 1997; PCE of heavy vehicles (HV) varied depending on the road types. PCE of heavy vehicles that according to MKJI 1997 is used as a median; PCE of motorcycles (MC) of MKJI 1997 need to be adjusted to 0.4 or more, particularly in the calculation of actualy traffic flow.

Total Capacities at All-Way Stop-Controlled Intersections: Validation and Comparison of Highway Capacity Manual Procedure and Addition-Conflict-Flow Technique

2002 ◽  
Vol 1802 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Ning Wu
Keyword(s):  
Computational Procedure ◽  
Flow Conditions ◽  
Passenger Cars ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Iterative Model ◽  
Sufficient Detail ◽  
The Subject ◽  
Total Capacity

An iterative model for computing capacities at all-way stop-controlled (AWSC) intersections has been included in the new Highway Capacity Manual (HCM) 2000. The model is based on five saturation headway values, each reflecting a different level of conflict faced by the subject-approach driver. From this model the capacity and service time at any approach can be computed using iterative calculations. The model in the HCM is a so-called approach-based model, which only takes into account the conflicting cases among the approaches. The effect of turning streams or movements is not modeled in sufficient detail. In contrast, a theoretical, stream-based model for determination of capacities at AWSC intersections has been developed. This model is based on the addition-conflict-flow (ACF) method developed from graph theory and takes into account all the traffic streams at the intersection. This allows a systematic and realistic analysis of the traffic process at AWSC intersections. The computational procedure included in the model can be conducted without iterative calculation steps. The ACF and the HCM models for intersections with single-lane approaches were comprehensively validated, as well as a modified version of the HCM model that significantly enhances its features. The results of the validation indicate that the total capacity of an AWSC intersection with single-lane approaches based on the HCM model ranges between 1,450 and 1,550 passenger cars per hour (pc/h), whereas the total capacity based on the ACF model ranges between 1,600 and 2,000 pc/h. The modified HCM model yields total capacities ranging between 1,700 and 2,000 pc/h. The ACF model and the modified HCM model yield similar capacity results under normal traffic flow conditions.

Impact of Including Exiting Vehicles in Single-Lane Roundabout Capacity Models

2015 ◽  
Vol 2517 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Wonho Suh ◽  
Christina Barry ◽  
Laura Schmitt ◽  
James Anderson ◽  
Michael O. Rodgers ◽  
...  
Keyword(s):  
Current Method ◽  
Highway Capacity ◽  
Low Speed ◽  
Operational Conditions ◽  
Highway Capacity Manual ◽  
Video Imagery ◽  
The Impact ◽  
A Current ◽  
Capacity Estimates

Roundabouts are classified as alternative intersection forms because they provide operational conditions not found at conventional intersections (e.g., a low-speed environment and fewer possible vehicle conflicts). Such conditions provide a combination of safety and operational benefit that normally is not achievable at a conventional intersection. The ability to predict capacity accurately is important when alternative intersection designs are examined. Highway Capacity Manual 2010 provides a current method for determining the capacity of a roundabout approach in which vehicles that exit on the same approach are considered not to influence capacity. However, the inclusion of exiting vehicles in the model creates a different circulating vehicle gap distribution (dividing larger gaps into smaller gaps) that reduces the number of opportunities to measure follow-up headway. Also, most critical headway values for the analysis are smaller than the critical headway values found when exiting vehicles are excluded. Capacity equations were developed from video imagery recorded for 28 approaches at 13 roundabouts, and the impact of including exiting vehicles in the analysis of single-lane roundabout capacity was evaluated. Vehicles exiting the roundabout were found to have a measurable impact on the estimated capacity of the roundabout approach. Both follow-up and critical headway values decreased when exiting vehicles were included. Also, the estimated capacity including exiting vehicles was found to increase or decrease (relative to capacity estimates that excluded exiting vehicles) depending on the percentage of conflicting vehicles that were exiting vehicles.

scholarly journals COMPARATIVE ANALYSIS OF METHODS FOR DETERMINATION OF SUPPLY FLOWS

2021 ◽  
pp. 64-78
Author(s):  
Nataliia Semchenko ◽  
Olha Kholodova ◽  
Maryna Buhaiova
Keyword(s):  
Comparative Analysis ◽  
Traffic Flow ◽  
Analytical Calculation ◽  
Signalized Intersections ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Flow Parameters ◽  
Definition Of ◽  
Saturation Flow

Problem. The capacity of signalized intersections is determined using the concept of "saturation flow". It is the main characteristic in the process of their analysis, design and calculation. The work is devoted to solving the scientific-applied problem of increasing the efficiency of the signalized intersection at one level by choosing a rational method of determining saturation flows for these characteristics of traffic flows, geometric parameters of the intersection and infrastructure in its area. The subject of the study is the influence of the main characteristics of the traffic flow, parameters and infrastructure of the intersection on the saturation flow value. Goal. The aim of the work is the analysis of the influence of the main characteristics of the traffic flow, parameters and infrastructure of the intersection on the saturation flow value. Methodology. The calculation of the control regime at the intersection is based on determining the relation between the traffic intensity of vehicles at the intersection and the saturation flow value, which changes under the influence of a number of factors. Analytical calculation of the saturation flow value is based on using of correction factors that take into account the influence of these factors. Results. The methods of determination of saturation flows are analyzed out in the work; performed a comparative analysis of the definition of ideal saturation flows by different methods; a comparative analysis of the determination of the saturation flow correction coefficients for the parameters that have an effect on it were performed; the estimation of discrepancy at calculations of coefficients of correction of saturation flows by various methods is done; the list of coefficients which need to be considered at definition of their influence on a saturation flow is refined. Originality. In oppose to classical and other approaches to determining the saturation flow, the method recommended by the American "Highway Capacity Manual" takes into account more parameters of influence. It is proposed to use this method for the saturation flow calculation, but with an updated list of coefficients that must be taken into account in the calculations. Practical value. The results of the work can be used in the practice of improving the efficiency of signalized intersections in sections of the urban road network, as well as in further research on this topic.

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