Faculty Publications
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Item Study of unique merging behavior under mixed traffic conditions(Elsevier Ltd, 2015) Kanagaraj, V.; Srinivasan, K.K.; Sivanandan, R.; Asaithambi, G.Roads in developing countries carry mixed traffic with wide variations in static and dynamic characteristics of vehicles. The traffic flow is also generally devoid of lane discipline, with vehicles occupying any available road space ahead. In such a regime of traffic flow, the phenomena of merging of vehicles at intersections of two roads is complex, warranting further study. The merging maneuvers at T-intersections under congested traffic conditions were studied microscopically through video-recording. In congested situations, the merging vehicle attempts a complex merging maneuver to enter the main traffic stream. Two unique merging processes are commonly observed in mixed traffic: group and vehicle cover merging (these are generally not observed in countries such as US). The author is using these words first time in this study. These reflect the different types of driver behavior - merging in groups, and by taking cover of another vehicle. Probabilistic models for group and vehicle cover merging are developed that capture this unique merging behavior. Comprehensive microscopic data collection and extraction were carried out to study the merging process at T-intersection under congested conditions. Merging models were then estimated using maximum likelihood method with disaggregate data that was collected for a case study T-intersection in Chennai city, India. Such models can find applications in simulation of highly congested traffic flow in a realistic manner under mixed traffic conditions. They can also give insights on devising better traffic control measures at such intersections. © 2015 Elsevier Ltd.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 Evaluation of Intersection Traffic Control Measures through Simulation(Springer India sanjiv.goswami@springer.co.in, 2015) Asaithambi, G.; Sivanandan, R.Modeling traffic flow is stochastic in nature due to randomness in variables such as vehicle arrivals and speeds. Due to this and due to complex vehicular interactions and their manoeuvres, it is extremely difficult to model the traffic flow through analytical methods. To study this type of complex traffic system and vehicle interactions, simulation is considered as an effective tool. Application of homogeneous traffic models to heterogeneous traffic may not be able to capture the complex manoeuvres and interactions in such flows. Hence, a microscopic simulation model for heterogeneous traffic is developed using object oriented concepts. This simulation model acts as a tool for evaluating various control measures at signalized intersections. The present study focuses on the evaluation of Right Turn Lane (RTL) and Channelised Left Turn Lane (CLTL). A sensitivity analysis was performed to evaluate RTL and CLTL by varying the approach volumes, turn proportions and turn lane lengths. RTL is found to be advantageous only up to certain approach volumes and right-turn proportions, beyond which it is counter-productive. CLTL is found to be advantageous for lower approach volumes for all turn proportions, signifying the benefits of CLTL. It is counter-productive for higher approach volume and lower turn proportions. This study pinpoints the break-even points for various scenarios. The developed simulation model can be used as an appropriate intersection lane control tool for enhancing the efficiency of flow at intersections. This model can also be employed for scenario analysis and can be valuable to field traffic engineers in implementing vehicle-type based and lane-based traffic control measures. © 2015, The Institution of Engineers (India).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 Location prediction algorithm for a nonlinear vehicular movement in VANET using extended Kalman filter(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Jaiswal, R.K.; Jaidhar, C.D.Vehicular ad-hoc network (VANET) is an essential component of the intelligent transportation system, that facilitates the road transportation by giving a prior alert on traffic condition, collision detection warning, automatic parking and cruise control using vehicle to vehicle (V2V) and vehicle to roadside unit (V2R) communication. The accuracy of location prediction of the vehicle is a prime concern in VANET which enhances the application performance such as automatic parking, cooperative driving, routing etc. to give some examples. Generally, in a developed country, vehicle speed varies between 0 and 60 km/h in a city due to traffic rules, driving skills and traffic density. Likewise, the movement of the vehicle with steady speed is highly impractical. Subsequently, the relationship between time and speed to reach the destination is nonlinear. With reference to the previous work on location prediction in VANET, nonlinear movement of the vehicle was not considered. Thus, a location prediction algorithm should be designed by considering nonlinear movement. This paper proposes a location prediction algorithm for a nonlinear vehicular movement using extended Kalman filter (EKF). EKF is more appropriate contrasted with the Kalman filter (KF), as it is designed to work with the nonlinear system. The proposed prediction algorithm performance is measured with the real and model based mobility traces for the city and highway scenarios. Also, EKF based prediction performance is compared with KF based prediction on average Euclidean distance error (AEDE), distance error (DE), root mean square error (RMSE) and velocity error (VE). © 2016, Springer Science+Business Media New York.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.Item Investigating bus stops' influence on saturation flow at signalized intersections in heterogeneous traffic(Aracne Editrice, 2022) Shubhashree, K.S.; Mohan, M.The public transportation system efficiently reduces congestion and pollution as they lessen the dependency on personalized modes. However, most bus stops are located close to the intersection, and the stopping buses often create a bottleneck. At signalized intersections, this will seriously impact the saturation flow as it hinders the efficient functioning of the traffic signal system, resulting in delays and reduction of the intersection's capacity. Hence, a profound understanding of the factors associated with bus stoppages, which influence the saturation flow, is essential in designing efficient signalized intersections. This study simulates traffic flows at signalized intersections in heterogeneous traffic in a micro-simulation software VISSIM. Results of multiple simulation run indicated that saturation flow at intersections depends on the percentage of buses in the vehicular mix, the distance of bus stop from the stop line, and percentages of right and left-turning traffic. Further, the study proposes separate saturation flow models for upstream and downstream bus stop conditions. These could be used to optimally place bus stops near the intersection such that it does not hamper the performance of the intersection while not causing any undue discomfort to the bus passengers. © 2022, Aracne Editrice. All rights reserved.Item Towards Sustainable Transport: An Analysis of Urban Mobility in Hyderabad, Telangana Using Uber Movement Data(Budapest University of Technology and Economics, 2025) Kuchu, J.; Tatipamula, S.; Ankam, C.; Birukuri, N.Cities worldwide face traffic congestion, challenging sustainable development and requiring insight into its dynamics, dispersion, and stability. Effective traffic management is pivotal for fostering sustainable urban mobility and enhancing quality of life. Leveraging Uber movement data, this study examines travel times and speeds across Hyderabad over a four-year span from 2016 to 2019. Congestion and friction indices from travel time matrices, along with network analysis, gauge urban accessibility, revealing similar magnitudes of Congestion and Travel Time Delay Transition Indices for inbound and outbound traffic within specific intervals. Notably, there is an inverse proportional relationship between these two indices. The Congestion Index values indicate that most zones experience significant traffic jams, while the Travel Time Delay Transition Index was calculated to affirm its inverse relationship with the Congestion Index. Employing fractal geometry, the study delves into the spatial complexity of the network and its correlation with urban growth parameters, contributing to sustainable urban planning efforts. Furthermore, the fractal dimension value obtained from the Mass-Radius method is 1.6955, with a correlation coefficient of 0.99, indicating a high degree of linearity between the road network and friction index. Results underscore the intricate interplay between traffic congestion, macroeconomic factors, and urban form, highlighting the imperative of integrating sustainability principles into transportation policies. By leveraging readily available Uber movement data, this research provides a comprehensive assessment of citywide traffic conditions, offering valuable insights for crafting sustainable transportation management strategies aimed at mitigating congestion and promoting equitable access to mobility. © 2025 Budapest University of Technology and Economics. All rights reserved.