Faculty Publications
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Item Evaluation of right-turn lanes at signalized intersection in non-lane-based heterogeneous traffic using microscopic simulation model(Maney Publishing michael.wagreich@univie.ac.at, 2015) Asaithambi, G.; Sivanandan, R.In developing countries like India, the traffic on urban roads is highly heterogeneous in nature, with vehicles of widely varying static and dynamic characteristics. This type of traffic is characterized by lack of queue and lane discipline (lane-less movement) based on availability of spaces near intersections. Moreover, at intersections, straight-through, left-, and right-turning vehicles seek to occupy the same physical space. In such situations, the through vehicles are susceptible to delays in the absence of turn lanes for the left-turning and right-turning vehicles and vice versa. Models suitable for analysis of such traffic flow hardly exist, and most of the available models are limited in scope. In the current study, a microscopic traffic simulation model for signalized intersection is developed specifically for heterogeneous traffic. This model covers different vehicle types and allows for some special behavior, such as seepage of two-wheelers to fronts of queues. Detailed study of queue formation and dissipation were done microscopically under non-lane-based traffic conditions near intersection area. The model was calibrated and tested with data from Chennai city, India, and its predictions were found to be in close agreement with the field data. In addition, the model makes a significant contribution to the study of right-turn lane (RTL) on delays to vehicles. In general, RTL is found to be advantageous for most cases of approach volumes and right-turn proportions. The optimal lengths of RTL are suggested for various approach volumes and right-turn proportions. © 2015 W. S. Maney & Son Ltd.Item Microscopic simulation for modeling exclusive stopping space for motorcycles under non-lane based mixed traffic conditions(Institute for Transport Studies in the European Economic Integration, 2015) Asaithambi, G.; Kumar, R.V.Y.; Sivanandan, R.Mixed traffic flow with high composition of motorcycles is a common situation in many urban areas in South Asian countries like India. It consists of vehicles having diverse static and dynamic characteristics. This type of traffic is characterized by lack of queue and lane disciplines. Motorcycles, due to their smaller size, have greater freedom to manoeuver in a mixed traffic stream. They tend to accumulate near the stop line by weaving through gaps between other vehicles during the red phase. The provision of Exclusive Stopping Space for Motorcycles (ESSM) near the stop line is believed to be beneficial in discharging the motorcycles faster, thereby enhancing the efficiency of the intersection. A microscopic traffic simulation model for a signalized intersection developed specifically for mixed traffic was used in this study. The model was calibrated and tested wit h dat a from Chennai city, India. This model was used to simulate traffic flow at an intersection assuming the presence of ESSM. The efficacy of ESSM was evaluated by varying the vehicular composition, traffic volume and ESSM lengths. The findings show that for certain composition, volume levels and lengths of ESSM, delays to vehicles decrease, thereby indicating its benefits. © 2015 European Transport\Trasporti Europei.Item Passenger car unit estimation at signalized intersection for non-lane based mixed traffic using microscopic simulation model(Budapest University of Technology and Economics office@pp.bme.hu Budafoki ut 4 Budapest H-1111, 2017) Asaithambi, G.; Mourie, H.S.; Sivanandan, R.In India, traffic on roads is mixed in nature with widely varying static and dynamic characteristics of vehicles. At intersections, vehicles do not follow ordered queue and lane discipline. Different vehicle types occupy different spaces on the road, move at different speeds, and start at different accelerations. The problem of measuring volume of such mixed traffic has been addressed by converting different vehicles categories into equivalent passenger cars and expressing the volume in terms of Passenger Car Unit (PCU) per hour. The accurate estimation of PCU values for different roadway and traffic conditions is essential for better operation and management of roadway facilities. Hence, the objective of the present study is to estimate the PCU values at signalized intersection in mixed traffic and to study the influence of traffic volume, traffic composition and road width on PCU values. For this purpose, a mixed traffic simulation model developed specifically for a signalized intersection was used. The model was calibrated and validated with the traffic data collected from a signalized intersection in Chennai city. Simulation runs were carried out for various combinations of vehicular composition, volume levels and road width. It was observed that presence of heavy vehicles and increase in road width affects the PCU values. The obtained PCU values were statistically checked for accuracy and proven to be satisfied. The PCU values obtained in this study can be used as a guideline for the traffic engineers and practitioners in the design and analysis of signalized intersections where mixed traffic conditions exist.Item Study of traffic flow characteristics using different vehicle-following models under mixed traffic conditions(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Asaithambi, G.; Kanagaraj, V.; Srinivasan, K.K.; Sivanandan, R.To understand the congestion problem and the occurrence of bottlenecks and to formulate solutions for it, a thorough study of vehicle-to-vehicle interactions is necessary. Car-following models replicate the behavior of a driver following another vehicle. These models are widely used in the development of traffic simulation models, and in analysis of safety and capacity. In India, traffic on roads is mixed in nature with wide variations in physical dimensions and other vehicular and traffic characteristics with loose lane discipline. In mixed traffic conditions, leader-follower vehicle types are not only car–car cases but also there are different combinations of vehicles (e.g. car-two wheeler, two wheeler-auto rickshaw, and heavy vehicle-two wheeler). The present study focuses on evaluation of different vehicle-following models under mixed traffic conditions. The car-following models such as Gipps, Intelligent Driver Model (IDM), Krauss Model and Das and Asundi were selected for this study. These models were implemented in a microscopic traffic simulation model for a mid-block section. The performance of different vehicle-following models was evaluated based on different Measure of Effectiveness (MoE) using field data collected from a four-lane divided urban arterial road in Chennai city. Speed-concentration and flow-concentration relationships for different vehicle-following models were developed and analyzed for different compositions. Capacity is higher when the proportion of smaller size vehicles is higher, since these vehicles use longitudinal and lateral gaps effectively. The simulation model was also applied to evaluate a range of traffic control measures based on vehicle type and lane (Ex: exclusion of auto-rickshaws, heavy vehicles, auto-rickshaws + heavy vehicles, etc.). The results showed the promise of some measures based on vehicle class, namely, the exclusion of auto rickshaws or auto rickshaws and heavy vehicles. The findings have interesting implications for capacity and PCU estimation and Level of Service (LoS) Analysis. © 2016 Informa UK Limited, trading as Taylor & Francis Group.