Modelling the Equivalency Factor of E-Rickshaw under Heterogeneous Traffic Conditions

A conflict-based safety assessment technique for rear-end crash risk at signalized intersections in a lower-middle-income country: A comparison between homogeneous and heterogeneous traffic conditions

Identification of Free Flowing Vehicles on Two Lane Intercity Highways under Heterogeneous Traffic condition

The assessment of travel time reliability enables precise prediction of travel times, better activity scheduling and decisions for all users of the road network. Furthermore, it helps to monitor traffic flow as a crucial strategy for reducing traffic congestion and ensuring high-quality service in urban roads. Travel time reliability is a useful reference tool for evaluating transport service quality, operating costs and system efficiency. However, many analyses of travel time reliability do not provide true travel variation under heterogeneous traffic flow conditions where traffic flow is a mixture of motorized and non-motorized transport. This study analysed travel time reliability under heterogeneous traffic conditions. The travel reliabilities focused on passenger waiting time at bus stops, in-vehicle travel time, and delay time at intersections which were analysed using buffer time, standard deviation, coefficient of variation, and planning time. The data used were obtained from five main bus routes in Dar es Salaam. The results indicate low service reliability in the outbound directions compared to inbound directions. They also intend to raise awareness of policy-makers about the situation and to make them shift from expanding road networks towards optimising road operations.

ABSTRACTThe primary objectives of this study are to develop two signalized-based roundabouts entry capacity model by employing regression-based multiple non-linear regression model (MNLR) and artificial intelligence-based age-layered population structure genetic programming (ALPS GP) model under heterogeneous traffic conditions. Based on the modified rank index (MRI) values, the ALPS GP model is found to be most suitable model under heterogeneous traffic conditions. However, in a practical point of view, MNLR-based signalized model is recommended for determining roundabout entry capacity under heterogeneous traffic conditions. Sensitivity analysis reports that weaving length is the prime variable and sharing about 27.72 % in the MNLR-based signalized roundabout entry capacity model. These findings will be useful for traffic planners and designers in the capacity estimation of signalized roundabouts under heterogeneous traffic conditions in developing countries with similar traffic characteristics as India.

Traffic stream models provide relationship among the three basic macroscopic traffic stream characteristics namely traffic speed, volume and density. Traffic stream models are the basic building blocks of traffic flow modeling, design of road systems and traffic management systems. A number of research papers are available proposing different traffic stream models. However, majority of them are based on homogeneous traffic conditions and they may not be directly suitable for the Indian traffic condition. Not much research has been done on this important aspect so far in India. The present study is an attempt to develop a traffic stream model suitable for the heterogeneous traffic flow condition, such as the one existing in India, taking Chennai as case study. Traffic data for the present study are collected using video graphic technique. Flow, speed and occupancy are manually extracted from collected videos and density estimated using the relation connecting occupancy and density. The results show an exponential speed-density relation and parabolic relations for the other two.

The level of service on urban roads quality experienced by the drivers will be varying it is difficult to study the variations due to heterogeneous traffic flow conditions of Indian urban roads. As per TRB, 2010 macroscopic traffic flow parameters are found to be deficient in capturing the quality of service on urban roads experienced by users. Hence the objective of the study is to develop new methodology to evaluate the urban roads in heterogeneous traffic conditions considering the microscopic parameters of traffic flow in a four-lane divided urban corridor. The speed profile of the motorised two-wheelers both in free flow and peak flow were collected from the urban corridor of Bangalore Karnataka, India. Using GPS based mobile application. From the speed profile data, the speed variation characteristics were studied. The various speed indices considered in the study are VN (Velocity noise), CV (Co-efficient of variation), AN (Acceleration noise), and MVG (Mean Velocity Gradient). The CV is considered as the measure of effectiveness, higher the CV more will be the variation of quality experienced by the road users.

Entry Capacity Quantifying Model through Drivers’ Behavior at Roundabouts

Passenger car units (PCU) play a pivotal role in the measurement of level of service (LOS) and capacity analysis of signalised intersections in developing countries where heterogeneous traffic conditions are prevalent. Literatures are available with different methods for estimating dynamic PCU values, but less of researches are done on their evaluation based on field measurements. This paper brings out a comparative analysis of estimated dynamic PCU values for signalised intersections having heterogeneous traffic conditions focusing on two methods—(1) dynamic PCU estimation using time headway ratio method and (2) dynamic PCU estimation using clearance time and projected area of vehicles. These two methods are compared with respect to the saturation flow at three signalised intersections to establish the suitability of these methods for dynamic PCU estimation for signalised intersections with heterogeneous traffic conditions. Results show that dynamic PCU estimation based on time headway ratio method and simulation model involving traffic volume and composition analysis goes in better conformity with the Indo-HCM method of saturation flow assessment for signalised intersections with heterogeneous traffic conditions. KeywordsDynamic PCUHeterogeneous trafficSaturation flowSignalised intersections

Identification of platoon dispersion pattern under heterogeneous traffic conditions

Honking noise corrections for traffic noise prediction models in heterogeneous traffic conditions like India

The performance of signalized intersections is usually evaluated by measuring delay occurring to vehicles which are passing through the signalized intersections. The field delay under heterogeneous traffic condition will be influenced by many parameters such as cycle time, traffic volume, degree of saturation, percentage of different vehicle categories especially the bunching of motorized two wheelers. In the present research work, the delay is estimated from the field using Indian Highway Capacity Manual (Indo HCM) (2017) procedure and the bunching effect of motorised two wheelers is studied on delay at signalized intersections under heterogeneous traffic conditions. Also, a linear delay model is developed for control delay estimation considering heterogeneous traffic conditions. From the field data, it was observed that, the percentage of motorised two wheelers in a bunch is varying from 37% to 57% whereas the total average delay occurred to vehicles which are passing the approach is varying from 106 s to 163 s respectively.

Increasing queue lengths while reducing average vehicle speeds is a notable criterion in intersections with heterogeneous traffic conditions. Such queue lengths vary with different intersection controls. This study aimed to estimate the queue length at un-signalized intersections with heterogeneous traffic conditions. The study was done for un-signalized intersections in Peradeniya and Weliwita, Sri Lanka and the data were collected through video recordings. The queue lengths in an un-signalized intersection with mixed traffic conditions have an instantaneous aggressive variation due to the uncontrolled movements. Thus, a time series analysis with the aid of Vector Auto Regression (VAR) model was used in order to estimate the queue length. Variables considered in this study were arrival flow rate, discharge flow rate, number of conflicts for 15 seconds time intervals as independent variables and queue length at the end of each 15 seconds as the dependent variable. For the modelling, the procedure of “Box-Jenkins” method was followed. After the confirmation of the variables are stationary, Cointegration check and Granger causality tests were done to check the cointegration between variables and the granger causality between variables. Then, VAR models were developed using 80% data from the total data set for both locations. The remaining 20% of the data set was used to validate the model using the MAE, MAPE, and RMSE error values between the actual and predicted queues. Among both models, 0.94 of higher R2 value and Durbin Watson value as 2 was obtained for the developed model using raw variables for Weliwita junction. Furthermore, the observed MAE, MAPE, and RMSE values for Weliwita model were 3,5 and 6%, respectively. Thus, the results of this study can be used to reduce traffic congestion while enhancing the safety of the users at un-signalized intersections in Sri Lanka. KEYWORDS: heterogeneous traffic, queue length, time series analysis, un-signalized intersections.

Analysis of queue discharge characteristics at signalized intersections is a primary component of traffic signal analysis and design. On the basis of previous studies, mainly conducted in homogeneous traffic conditions, the discharge headway is assumed to be high at the start of green for the first few vehicles, mainly because of start-up lost times, and is also assumed to reach the minimum value by the fourth or fifth vehicle in the queue. The minimum headway is expected to continue until the end of the queue. However, this may not be the case under heterogeneous traffic conditions, such as those in India, which has the additional problem of lacking lane discipline. Most of the signals in India include a countdown timer that indicates the time left for the signal phase, which is also expected to affect queue discharge characteristics. This paper presents insights gained on queue discharge characteristics at signalized intersections under heterogeneous traffic conditions and on the effect of a countdown timer on the headway distribution. The analysis was carried out using data collected from two intersections, one with a timer and one without, in Chennai, India, through the use of a videographic technique. The data collected are classified into three discharge regimes: start-queue, mid-queue, and end-queue. Linear regression models are used to assess the impact of vehicle types on queue discharge characteristics. The results indicate that the accepted headway distribution is followed when there is no timer. However, with the presence of a timer, there is a clear change in the trend for reduced start-up lost time and end lost time.

Investigating the influence of conflicting flow’s composition on critical gap under heterogeneous traffic conditions

In homogeneous form of traffic, the vehicles in traffic are not so versatile and the vehicles move in dedicated lanes, whereas in countries such as India, the form of traffic is heterogeneous in nature where the traffic is very versatile with many combinations of vehicles which rarely move in dedicated lanes. The combinations make it harder to calculate the headway, PCU, etc. because every vehicle possesses a different shape and size. The lack of use of dedicated lanes makes it very tough to check which vehicle belongs to which queue and how it will move or accelerate. Hence, the methodology used for homogeneous traffic condition fails drastically when used in heterogeneous traffic conditions. The recent researches based on heterogeneous form of traffic do not present us with a reliable methodology to compute or calculate the saturation flow in heterogeneous traffic condition. This makes it difficult to design and plan the working of intersections because the traffic almost always tends to move differently than the calculated outcome. The current research is primarily focused on the development of a reliable methodology which can present us with a more accurate saturation flow traffic data, i.e. intersection capacity in heterogeneous traffic conditions. In the clearance method, different factors such as effective turning radius, projected area of the vehicles, etc. are required for the calculation of saturation flow. In velocity method, during a traffic jam all the vehicles are almost at the same speed so the PCU deviates from its actual value making all PCU values of different vehicles almost the same. In India, we have heterogeneous type of conditions not homogeneous and also the lane discipline is not followed. In this clearance method, the study considers only a particular type of vehicle at an instance and we have to determine the clearance time it requires, i.e. the time it takes from curb line to front curb line.