Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
11 results
Search Results
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 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 Microsimulation approach for evaluation of reversible lane operation on urban undivided roads in mixed traffic(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Kotagi, P.B.; Asaithambi, G.Most of the urban cities in emerging countries consist of a large proportion of undivided roads which carry mixed traffic with non-lane discipline. Vehicular maneuvers on such roads are complex and also, traffic flow in a particular direction is predominant compared to other direction which increases the congestion. Possible ways to reduce congestion are to improve the operation of existing road systems through better traffic management measures. The objective of this research work is to evaluate reversible lane (tidal flow) operation using a microscopic simulation model developed specifically for urban undivided roads in mixed traffic. The concept of influence area is introduced in the model to identify the most influencing leader vehicle. The impact of reversible lane operation on road capacity is studied using different vehicular compositions commonly observed on urban arterials in Indian cities. Results shows that there is an improvement in capacity during peak hours after implementing reversible lanes. © 2019, © 2019 Hong Kong Society for Transportation Studies Limited.Item Congestion control performance investigation of ModQUIC protocol using JioFi network: A case study(IOS Press Nieuwe Hemweg 6B Amsterdam 1013 BG, 2020) Kharat, P.; Kulkarni, M.Quick UDP Internet (QUIC) protocol is a transport and application layer solution developed by Google, which is the strong competitor to popular and well established Transmission Control Protocol (TCP). The QUIC protocol is being updated faster resulting into many new versions of the protocol. In this paper, the performance of Modified QUIC (ModQUIC) protocol has been tested with respect to congestion control using India's rapidly growing Internet service provider, the Reliance Jio 4G network (JioFi), which has captured 17% of the market share in a short time. This experimental study investigated ModQUIC protocol performance with congestion control mechanisms CUBIC and Bottleneck Bandwidth Round-trip-propagation-time (BBR) in the JioFi network. The experiment is conducted using a testbed, developed with JioFi and RaspberryPi-3 wireless router along with network emulator: Netem. The ModQUIC performance is verified using test video files stored on Google drive. The performance is tested in packet loss and packet reorder situations using metrics, Throughput and Retransmission Ratio (RTR). We observed that overall ModQUIC/BBR performance is better than ModQUIC/CUBIC in the current Internet. We observed that Reliance Jio is an economical solution for highly populated countries like India, but not a contemporary solution to fulfill India's newly launched digitization project. © 2020 - IOS Press and the authors. All rights reserved.Item O-SegNet: Robust Encoder and Decoder Architecture for Objects Segmentation from Aerial Imagery Data(Institute of Electrical and Electronics Engineers Inc., 2022) Eerapu, K.K.; Lal, S.; Narasimhadhan, A.V.The segmentation of diversified roads and buildings from high-resolution aerial images is essential for various applications, such as urban planning, disaster assessment, traffic congestion management, and up-to-date road maps. However, a major challenge during object segmentation is the segmentation of small-sized, diverse shaped roads, and buildings in dominant background scenarios. We introduce O-SegNet- the robust encoder and decoder architecture for objects segmentation from high-resolution aerial imagery data to address this challenge. The proposed O-SegNet architecture contains Guided-Attention (GA) blocks in the encoder and decoder to focus on salient features by representing the spatial dependencies between features of different scales. Further, GA blocks guide the successive stages of encoder and decoder by interrelating the pixels of the same class. To emphasize more on relevant context, the attention mechanism is provided between encoder and decoder after aggregating the global context via an 8 Level Pyramid Pooling Network (PPN). The qualitative and quantitative results of the proposed and existing semantic segmentation architectures are evaluated by utilizing the dataset provided by Kaiser et al. Further, we show that the proposed O-SegNet architecture outperforms state-of-the-art techniques by accurately preserving the road connectivity and structure of buildings. © 2017 IEEE.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 Visualization and Assessment of the Effect of Roadworks on Traffic Congestion Using AVL Data of Public Transit(Springer Nature, 2022) Harsha, H.; Mulangi, R.H.; Kulkarni, V.Congestion-free movement of traffic during peak hours in urban areas is rarely witnessed nowadays. Several factors are responsible for traffic congestion, and a large amount of reliable data is necessary to investigate them. In this study, we investigated the effectiveness of automated vehicle location (AVL) data of public transit in evaluating the effect of route diversion due to roadworks on traffic congestion. The public transit vehicle data from Mysore intelligent transport system were used for the purpose. In the preliminary analysis, the spatiotemporal variations in the speed data of public transit were visualized using spatiotemporal speed plots. A comparison study of traffic states in an urban street and an arterial road was conducted using a visualization tool. The data from Inner Ring Road of Mysore city were used to evaluate the effect of roadworks on traffic congestion. The road links of Inner Ring Road were evaluated for two scenarios: normal scenario and route diversion scenario. The results revealed that the spatiotemporal visualization technique can be used to diagnose the changes in traffic congestion, especially near intersections and bus stops. It is concluded that the AVL data from public transit buses proves to be a potential data source for traffic state prediction and evaluation of traffic congestion. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item ESMA: Towards elevating system happiness in a decentralized serverless edge computing framework(Academic Press Inc., 2024) Datta, S.; Addya, S.K.; Ghosh, S.K.Due to the rapid growth in the adoption of numerous technologies, such as smartphones and the Internet of Things (IoT), edge and serverless computing have started gaining momentum in today's computing infrastructure. It has led to the production of huge amounts of data and has also resulted in increased network traffic, which if not managed well can cause network congestion. To address this and maintain the quality of service (QoS), in this work, a novel dispatch (destination selection) algorithm called Egalitarian Stable Matching Algorithm (ESMA) for faster data processing has been developed while also considering the best use of server resources in a decentralized Serverless-Edge environment. This will allow us to effectively utilize the enormous volumes of data that are generated. The proposed algorithm has been able to achieve lower overall dissatisfaction scores for the entire system. Individually, the client's happiness as well as the server's happiness have improved over the baseline. Moreover, there has been a drop of 25.7% in the total execution time and the total network resources consumed are lower as compared to the baseline algorithm as well as random-allocation algorithm. © 2023 Elsevier Inc.Item A dynamic traffic assignment framework for policy analysis in cities with significant share of two-wheelers(Elsevier Ltd, 2024) Chapala, S.B.K.; Nair, P.; Sreekumar, M.; Bhavathrathan, B.K.High maneuverability of motorized two-wheelers amidst vehicles of bigger size and different dynamics invalidates FIFO to traverse through the gaps between other vehicles for faster mobility. The failure of existing dynamic traffic assignment frameworks with multi-class conditions to capture this behaviour results in inaccurate routing. The study proposes a simulation based two-class dynamic traffic assignment framework comprising of two-wheeler specific behaviour. These features when incorporated in the framework will add to the utility of the traditional dynamic traffic assignment framework in travel time prediction and planning level applications and is therefore relevant to regions with significant share of two-wheelers. The study gives a clear view of the effect of two-wheeler specific features on the route choice behaviour based on the dynamic travel time. The results of the study shows that there occurs an unintentional separation of vehicle classes during congestion; this effect can be utilized for a two-wheeler specific policy implication for congestion management in cities. The proposed framework can be employed in identifying the optimal provision of exclusive two-wheeler lanes. It is also observed that the provision of exclusive lanes may sometimes be counterproductive. © 2023Item Spatio-temporal analysis of public transit gps data: Application to traffic congestion evaluation(Aracne Editrice, 2024) Harsha, H.M.; Mulangi, R.H.Congestion free mobility has become nearly impossible in most of the metropolitan cities of India especially during peak hours. The understanding of factors inducing congestion demands huge amount of data pertaining to urban traffic. The developed countries have adopted different kinds of automatic data collection systems such as loop detectors, surveillance cameras and radars for the data collection of road traffic condition. In developing countries like India, the collection and monitoring of data related to movement of traffic stream are mostly manual, very time consuming and expensive. In India, Intelligent Transport System (ITS) has been implemented to Mysore City public transport in the year 2012. This study makes use of Global Positioning System (GPS) data of Mysore ITS. The major objective of the present study is to evaluate the congestion on urban roads using public transit GPS data with the help of visualization techniques. Spatio-temporal visualization-based analysis has been carried out to evaluate the traffic congestion patterns of urban roads. Initially, the comparison of traffic states on urban street and arterial road has been carried out. Later, the difference in congestion patterns before and after the operation of grade separator and the impact of route diversion on the congestion patterns have been evaluated. This study shows that public transit GPS data can be a potential data source to evaluate the traffic state or congestion, especially when there are limited sources of traffic data. © 2024, Aracne Editrice. All rights reserved.