scholarly journals Concept of queue clearance rate for estimation of equivalency factors at priority junctions

2016 ◽  
Vol 43 (7) ◽  
pp. 593-598 ◽  
Author(s):  
Mithun Mohan ◽  
Satish Chandra
Keyword(s):  
Developing Countries ◽  
Clearance Rate ◽  
Developed Countries ◽  
Traffic Volume ◽  
Heterogeneous Traffic ◽  
Passenger Cars ◽  
Passenger Car ◽  
Traffic Conditions ◽  
Equivalency Factors ◽  
Equivalent Number

Traffic in developing countries is often distinguished from others for its diversity in vehicular composition and passenger car equivalents (PCE) becomes essential in such conditions for expressing traffic volume in terms of equivalent number of passenger cars. The PCE estimation at two-way stop-controlled intersections in developing countries is further complicated by the lack of movement priority and lane discipline. The study introduces a method to find PCE factors based on the time taken by a queue of vehicles to completely clear the intersection and composition of the queue. The method is validated through simulations in VISSIM software and was then used to derive PCE factors for three intersections in India. Although the method is developed and tested to estimate PCE factors under highly heterogeneous traffic at priority junctions in India, it is quite general in nature and can be used in traffic conditions found in developed countries as well.

Capacity estimation of unsignalized intersections under heterogeneous traffic conditions

2020 ◽  
Vol 47 (6) ◽  
pp. 651-662
Author(s):  
Mithun Mohan ◽  
Satish Chandra
Keyword(s):  
Developing Countries ◽  
Developed Countries ◽  
Heterogeneous Traffic ◽  
Traffic Operations ◽  
Capacity Estimation ◽  
Traffic Conditions ◽  
Unsignalized Intersections ◽  
Capacity Model ◽  
Gap Acceptance Theory ◽  
Entire Procedure

Capacity of movements at unsignalized intersections are usually estimated based on gap acceptance theory and accuracy of such estimation largely depends on the extent to which its inherent assumptions are satisfied. However, owing to the typical traffic operations at intersections in developing countries, many of these assumptions remain unsatisfied and hence, estimating capacity as per the procedure laid down in the capacity manuals of developed countries will prove inaccurate. The present research focuses on developing the entire procedure for estimating the capacities of movements at unsignalized intersections dealing with heterogeneous traffic. This study is based on data collected from eight different unsignalized intersections located in various parts of India and by using Harders’ capacity model as base, the procedure to estimate the parameters of this model is revised to suit the traffic operations in developing countries and further modifies the Harders’ model using the movement capacities measured in the field.

scholarly journals Comparative Analysis of Effects of Heavy Vehicles on Roads in Southern and Northern Nigeria

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
C. C. Osadebe ◽  
H. A. Quadri
Keyword(s):  
Northern Region ◽  
Design Guidelines ◽  
Traffic Volume ◽  
Southern Region ◽  
Heavy Vehicle ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
The Road ◽  
Equivalency Factors ◽  
On The Road

The prevalence of flexible pavement deterioration in the country has been adduced largely by highway researchers to trucks or heavy vehicles carrying much in excess of permitted legal limits. This study investigated levels of deterioration of Abuja-Kaduna-Kano road (Northern region) and Port Harcourt-Enugu road (Southern region) caused by heavy vehicles through a 14 day traffic counts conducted at 5 strategic points each in the Northern and Southern regions. Traffic data generated were analyzed with AASHTO Design Guidelines (1993) to evaluate Equivalent Single Axle Loads (ESALs) and Vehicle Damage effects on the road. The Traffic Volume, Average Daily Traffic (ADT), and Heavy Vehicle per day (HV/day) were estimated to be 2,063,977; 147,427; and 12,246 respectively in the Northern region, while in the Southern region they were estimated to be 750,381; 53,670; and 20,951 respectively. Motorcycles, Passenger cars, Mini-buses/Pick-ups, and Heavy vehicles constitute 18.7%, 49.7%, 23.3% and 8.31% of the total traffic volume respectively in the Northern region while in the South they constitute 4.6%, 30.1%, 26.2% and 39.1% respectively. ESALs were estimated according to AASHTO Design Guidelines in the Northern and Southern regions as 547,730 and 836,208 respectively. An average Load Equivalency Factors (LEFs) of 3.43 and 3.02 were estimated for each heavy vehicle plying the Northern and Southern roads respectively and this could explain some failures (alligator cracks, potholes, depressions, linear or longitudinal cracks along the centre line amongst others) inherent on the road.

Novel Area Occupancy–Based Method for Passenger Car Unit Estimation on Multilane Urban Roads Under Heterogeneous Traffic Scenario

2017 ◽  
Vol 2615 (1) ◽  
pp. 82-94 ◽  
Author(s):  
Raunak Mishra ◽  
Pallav Kumar ◽  
Shriniwas S. Arkatkar ◽  
Ashoke Kumar Sarkar ◽  
Gaurang J. Joshi
Keyword(s):  
Traffic Flow ◽  
Performance Measure ◽  
Area Ratio ◽  
Heterogeneous Traffic ◽  
Passenger Car ◽  
Traffic Conditions ◽  
Passenger Car Unit ◽  
Wide Range ◽  
Traffic Volumes ◽  
Measure Of Performance

This research was aimed at developing an area occupancy–based method for estimating passenger car unit (PCU) values for vehicle categories under heterogeneous traffic conditions on multilane urban roads for a wide range of traffic flow levels. First, PCU values of vehicle categories were determined according to the Transport and Road Research Laboratory definition and replaced the commonly considered measure of performance speed with area occupancy using simulation. The PCU values obtained were found to be significantly different for different volume-to-capacity ratios; this result shows that the PCU value is dynamic in nature. While the dynamic nature of PCU values is well appreciated, practitioners may prefer a single set of optimized PCU values (unique for each vehicle category). Hence, a new method with a matrix solution was proposed to estimate the optimized or unique set of PCU values with area occupancy as the performance measure. To check the credibility of the proposed method, the estimated PCU values were compared from existing guidelines regulated by the Indian Roads Congress (IRC) and values estimated with the widely accepted dynamic PCU concept of speed–area ratio. Results show that the PCU values suggested by IRC and the dynamic PCU concept using the speed–area ratio underestimate and overestimate the flows, respectively, at different traffic volumes. However, the values obtained with the area-occupancy concept were found to be consistent with the traffic flow in a cars-only traffic situation at different flow conditions. The derived set of optimized PCU values proposed can be useful for traffic engineers, researchers, and practitioners for capacity and level-of-service analysis under heterogeneous traffic conditions.

Effects of Speed Bumps and Humps on Motorcycle Speed Profiles

2014 ◽  
Vol 931-932 ◽  
pp. 536-540 ◽  
Author(s):  
Wichuda Satiennam ◽  
Thaned Satiennam ◽  
Pornsiri Urapa ◽  
Tussawan Phacharoen
Keyword(s):  
Developing Countries ◽  
Developed Countries ◽  
Vehicle Speed ◽  
Passenger Car ◽  
The Road ◽  
Acceleration Rate ◽  
Major Mode ◽  
Before And After ◽  
On The Road ◽  
Speed Humps

In developed countries, the use of speed humps and bumps have evolved from extensive research and testing which been properly designed and standardized. On the contrary in developing countries, no systematic and scientific studies have been carried out on that environment, especially the study on the effects that the motorcyclists response to the humps and bumps. This study therefore reveals the riders behavior when negotiating their speed to the devices. A case study was conducted in the provincial cities of Thailand where the motorcycle was a major mode of transportation. Six locations with speed humps and bumps were selected. Vehicles passing times were simultaneously recorded at 12 points along each traffic calmed link. From these data, a speed profile for each individual vehicle and for a link could be derived. It is found that speed humps and bumps have critically different impacts on motorcycle rider and passenger car driver. The smaller size speed bumps could effectively control the rider speed but have diverse impacts on the driver. These speed differences could post more safety deficiency to the site. The effect of the device on riders behavior, however, is restricted to a short spatial range (about 20-30 m before and after the device). For the speed humps, the motorcycle speeds are quite varied depending mainly on the road terrain. It is found that the motorcyclists have significant lower acceleration rate on the upgrade terrain when compared to the passenger car. Therefore, it is important to take all these rider characteristics into considerations when design the road humps to control vehicle speed in the developing countries.

scholarly journals MICROSIMULATION-BASED PASSENGER CAR EQUIVALENTS FOR HEAVY VEHICLES DRIVING TURBO-ROUNDABOUTS

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Orazio Giuffrè ◽  
Anna Granà ◽  
Sergio Marino ◽  
Fabio Galatioto
Keyword(s):  
Geometric Design ◽  
Heavy Vehicles ◽  
Passenger Cars ◽  
Highway Capacity ◽  
Passenger Car ◽  
Operational Conditions ◽  
Highway Capacity Manual ◽  
Traffic Conditions ◽  
Scenarios Simulation

Due to its geometric design, turbo-roundabouts impose greatest constraints to the vehicular trajectories; by consequence, one can expect a more unfavourable impact of heavy vehicles on the traffic conditions than on other types of roundabouts. The present paper addresses the question of how to estimate Passenger Car Equivalents (PCEs) for heavy vehicles driving turbo-roundabouts. The microsimulation approach used revealed as a useful tool for evaluating the variation of quality of traffic in presence of mixed fleets (different percentages of heavy vehicles). Based on the output of multiple runs of several scenarios simulation, capacity functions for each entry lane of the turbo-roundabout were developed and variability of the PCEs for heavy vehicles were calculated by comparing results for a fleet of passenger cars only with those of the mixed fleet scenarios. Results show a dependence of PCEs for heavy vehicles on operational conditions, which characterise the turbo-roundabout. Assuming the values of PCEs for roundabouts provided by the 2010 Highway Capacity Manual (HCM), depending on entering manoeuvring underestimation and overestimation of the effect of heavy vehicles on the quality of traffic conditions have been found.

Passenger car equivalents of trucks on four-lane rural freeways under lane restriction and different traffic conditions

2012 ◽  
Vol 39 (10) ◽  
pp. 1145-1155 ◽  
Author(s):  
Ciprian Alecsandru ◽  
Sherif Ishak ◽  
Yan Qi
Keyword(s):  
Flow Rate ◽  
Speed Limit ◽  
Linear Regression Models ◽  
Passenger Cars ◽  
Passenger Car ◽  
Highway Capacity Manual ◽  
Traffic Conditions ◽  
Common Policies ◽  
Traffic Composition ◽  
Differential Speed

Truck lane restriction and differential speed limits for trucks and passenger cars are becoming more common policies to improve freeway operations and safety. The most recent edition of the Highway Capacity Manual (HCM) recognizes that the passenger car equivalent (ET) values may differ with various traffic conditions, but does not explicitly address how ET values may be impacted by truck lane restrictions or differential speed limit policies. This study developed a flow-based methodology to determine ET for trucks under truck lane restriction policies and different levels of demand and traffic composition. A simulation model (VISSIM) was calibrated to reproduce ET in HCM on a level terrain freeway segment and then used to simulate various scenarios to capture the effect of demand flow rate, truck percentage, and compliance ratio to lane restriction, all under the enforcement of differential speed limit policy. The results showed that ET increases as the compliance ratio increases, regardless of the truck percentage and demand flow rate. For a given traffic flow rate, ET decreases as the truck percentage increases. Moreover, regardless of the compliance ratio to lane restriction and the truck percentage, ET increases with the demand flow rate. The statistical analysis revealed that the truck percentage has a significant effect on ET for most cases, except when the truck percentage exceeds 30%. The results also showed significant differences in ET for all demand flow rates at 95% confidence level. The study also developed linear regression models for each level of service to estimate the value of ET as a function of the truck percentage and compliance ratio.

scholarly journals Analyzing the Impact of Trucks on Traffic Flow Based on an Improved Cellular Automaton Model

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Dewen Kong ◽  
Xiucheng Guo ◽  
Bo Yang ◽  
Dingxin Wu
Keyword(s):  
Cellular Automaton ◽  
Traffic Flow ◽  
Traffic Congestion ◽  
Traffic Volume ◽  
Cellular Automaton Model ◽  
Passenger Cars ◽  
Passenger Car ◽  
Car Following ◽  
Proposed Model ◽  
The Impact

This paper aims to analyze the impact of trucks on traffic flow and propose an improved cellular automaton model, which considers both the performance difference between passenger cars and trucks and the behaviour change of passenger cars under the impact of trucks. A questionnaire survey has been conducted to find out whether the impact of trucks exists and how the behaviour of passenger car drivers changes under the impact of trucks. The survey results confirm that the impact of trucks exists and indicate that passenger car drivers will enlarge the space gap, decelerate, and change lanes in advance when they are affected. Simulation results show that traffic volume is still affected by percentages of trucks in the congestion phase in the proposed model compared with traditional heterogeneous cellular automaton models. Traffic volume and speed decrease with the impact of trucks in the congestion phase. The impact of trucks can increase traffic congestion as it increases. However, it has different influences on the speed variance of passenger cars in different occupancies. In the proposed model, the relative relationship of the space gap between car-following-truck and car-following-car is changeable at a certain value of occupancy, which is related to the impact of trucks.

Measuring the Passenger Car Equivalent of Small Cars and SUVs on Rainy and Sunny Days

2018 ◽  
Vol 2672 (31) ◽  
pp. 110-119 ◽  
Author(s):  
Majid Zahiri ◽  
Xiqun (Michael) Chen
Keyword(s):  
Field Investigation ◽  
Urban Traffic ◽  
Heterogeneous Traffic ◽  
Motor Vehicles ◽  
Mixed Traffic ◽  
Passenger Cars ◽  
Passenger Car ◽  
Passenger Car Equivalent ◽  
The Government ◽  
Rainy Days

Traffic volume is a fundamental measurement in traffic analyses. In mixed traffic, vehicles vary in size, length, headway, spacing, and acceleration/deceleration. Therefore, if we can categorize the vehicles in mixed traffic in greater detail, the estimated passenger car equivalent (PCE) number will be more accurate. Practical and appropriate methods that convert different vehicles into the equivalent number of passenger cars need to be employed to determine PCE factors for heterogeneous traffic. Following economic growth and increased use of motor vehicles in developing countries, the purchase of sports utility vehicles (SUVs) continues to grow, though the government encourages people to buy small cars because of the limited road capacity, as well as air pollution problems. In this research, we categorize passenger cars into three subsets: small cars (hatchback cars without a trunk), SUVs, and standard cars (taxis and typical family cars). A field investigation shows that the penetration rates of these passenger cars are 12%, 23%, and 55%, respectively (10% are other vehicles) in Hangzhou, China. We also measure the PCE value for small cars and SUVs using the mean time headway method. Because different countries have different weather conditions, we continue to measure the PCE values for sunny days and moderate rainy days. The results show that PCE values for small cars and SUVs are 0.87 and 1.26 on sunny days, and 0.87 and 1.31 on rainy days, respectively. By using the PCE with high precision, urban managers can accomplish the analysis of urban traffic with greater accuracy.

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