L. Vanajakshi

L. Vanajakshi
Indian Institute of Technology Madras | IIT Madras · Department of Civil Engineering

About

135
Publications
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2,112
Citations

Publications

Publications (135)
Article
Full-text available
In developing countries with limited or no availability of traffic sensors, theoretical delay models are the most commonly used tool to estimate control delay at intersections. The traffic conditions in such countries are characterised by a large mix of vehicle types and limited or no lane discipline (Heterogeneous, Less Lane-Disciplined (HLLD) tra...
Article
Full-text available
Providing expected time of arrival (ETA) information to passengers/operators with the help of the latest technologies is reported as a way to improve the effectiveness of the public transport system. There are several solutions to generate such information using automatic vehicle location data. Along with developing solutions, it is also equally im...
Article
Accurate bus travel time prediction in real-time is challenging, as numerous factors such as fluctuating travel demand, incidents, signals, bus stops, dwell times, and seasonal variations can affect travel time, a spatio-temporal variable. Literature that considered the spatio-temporal evolution of bus travel time adopting traffic flow theory-based...
Article
In recent times, the ubiquity of wireless technology has encouraged researchers to collect travel time data using Wi-Fi media access control scanners (WMS). This notion inspired the current work, which analyzed data from an in-house–developed WMS for potential intelligent transportation system (ITS) applications. First, the WMS was tested against a...
Article
Real-time bus travel time prediction has been an interesting problem since past decade, especially in India. Popular methods for travel time prediction include time series analysis, regression methods, Kalman filter method and Artificial Neural Network (ANN) method. Reported studies using these methods did not consider the high variance situations...
Article
Full-text available
Among the different strategies adopted to improve the efficiency and reliability of the bus services, bus signal priority is a low cost and less infrastructure- demanding solution that has the potential to reduce bus travel times in urban arterials. This paper develops analytical models for finding the thresholds for Green Extension (GE) and Red Tr...
Article
Dynamic prediction of queues and delays at signalized intersections utilize data obtained from automated traffic sensors as inputs for Intelligent Transportation Systems (ITS) applications. Errors are inevitable during automated data handling, especially when the traffic involved is heterogeneous and lacking in lane discipline. This paper presents...
Article
Full-text available
With the introduction of various automated sensors, traffic data collection has become easier and huge amount of data are getting accumulated over time. One of the interesting challenges in the field of intelligent transportation systems is to effectively utilize such large-scale database. Making meaningful inferences out of this data by conducting...
Article
Full-text available
An effective traffic control measure is the one that can significantly reduce delays incurred due to rising traffic congestion and improves travel time reliability. To achieve this, an accurate estimation of delay is very critical. The method of delay estimation varies with the type of data source available, and the type of data collected. This pap...
Article
In the absence of pharmaceutical interventions for the Novel Coronavirus (COVID-19), countries have taken drastic steps like quarantine, prohibit large-scale gatherings, limited transport, social distancing, curfews, and lockdowns to curtail the spread of the virus. In light of these events, the current study attempts to understand the short-term c...
Article
Bus signal priority (BSP) is an active traffic management measure to reduce bus travel delay at signalized intersections and to improve the bus service reliability. In this paper, we present a real-time BSP system with a primary focus on its practical implementation. We tackle two inter-related issues of existing priority systems, namely, real-time...
Article
Congestion has become a common experience to all road users in urban cities. In this regard, travelers desire travel time consistency—a reliability in the daily or hourly travel times. Travel time reliability measures are calculated from the day-to-day distribution of travel times on a particular route. Traditionally, travel time reliability measur...
Article
Travel time is one of the most important traffic parameters for travelers, traffic managers, planners, and operators alike. Travel time estimation is a significant component of any intelligent transportation systems (ITS) operations. In countries like India, which are at a nascent stage of ITS deployment, one of the main hurdles is the lack of accu...
Article
Travel time is a variable that varies over both time and space. Hence, an ideal formulation should be able to capture its evolution over time and space. A mathematical representation capturing such variations was formulated from first principles, using the concept of conservation of vehicles. The availability of position and speed data obtained fro...
Article
Full-text available
Arriving at optimal signal timing parameters to improve the efficiency of traffic flow has been one of the major challenges faced by traffic engineers. The choice of a robust optimization framework and an accurate traffic model plays a significant role in determining optimal signal timing parameters. Though traffic flow is intuitively stochastic, f...
Article
Efficient planning, operation and management of transportation facilities require extensive data regarding the traffic demand, patterns and conditions prevalent in the transportation network. Conventional data collection techniques such as loop detectors bear practical limitations such as limited accuracy and applicability, especially in mixed traf...
Article
Full-text available
The process of predicting or simulating traffic conditions, based on current and past traffic observations is an important component of any of the Intelligent Transportation System (ITS) applications. There are several methods to predict traffic count. However, each method in different literatures may use different datasets, different time interval...
Article
The computation of point-to-point shortest paths on time-dependent transportation networks has many practical applications. Finding the shortest path on transportation networks, taking into account prevailing dynamic traffic conditions, can help solve the problem of traffic congestion in urban areas. This study presents a framework for implementati...
Chapter
Efficient modelling of vehicular traffic is a challenging task in the context of Indian traffic conditions. One of the approaches for modelling traffic is using simulation. Though there are several traffic simulation software available, all of them are developed for the lane based and homogeneous traffic conditions. However, traffic conditions in m...
Article
The rapid advancements in sensor technologies has resulted in the increased use of Automatic Vehicle Location (AVL) systems for traffic data collection. Global Position System (GPS) sensors are the most commonly used AVL system, majorly because of it being a time-tested technology and being relatively cheap. Also, many of the transportation agencie...
Article
This paper reports the development of a public transport trip planner to help the urban traveller in planning and preparing for his commute using public transportation in the city. A Genetic Algorithm (GA) approach that handles real-time Global Positioning Systems (GPS) data from buses of the Metropolitan Transport Corporation (MTC) in Chennai City...
Article
Accurate prediction of arrival time of buses is still a challenging problem in dynamically varying traffic conditions especially under Indian traffic conditions. The present study proposes two predictive modelling methodologies using the concepts of time series analysis, namely (a) classical seasonal AR model with possible integrating non-stationar...
Article
Regulation of heterogeneous traffic is a challenging task on urban roads, particularly those where traffic congestion is routinely encountered. In this paper, a model based traffic signal control scheme via state feedback controller is presented. An original contribution of this study is the use of area occupancy as the measurement variable, which...
Conference Paper
Full-text available
Efficient planning, operation and management of transportation facilities require extensive data regarding the traffic demand, patterns and conditions prevalent in the transportation network. Conventional data collection techniques such as loop detectors bear practical limitations such as limited accuracy and applicability, especially in mixed traf...
Article
Full-text available
Studying patterns in traffic data is a basic analysis to understand the system. In this study, a large amount of bus travel data collected using vehicle tracking devices is analyzed for patterns. Travel time, in general, follows both spatial and temporal patterns. Spatial patterns are expected because travel times in particular sections on a roadwa...
Article
Full-text available
Managing congestion in mixed traffic conditions, characterized by heterogeneous and lane-less traffic, is a challenging task. Traditionally density, defined as the number of vehicles in a road stretch, is used to quantify congestion. However, direct measurement of density is difficult and hence is usually estimated from other variables. In this pap...
Article
Full-text available
This paper discusses the development of a novel off-line vision-based system to obtain the naturalistic trajectory database of traffic streams from recorded video footages. The developed system uses a semi-automatic mechanism that provides manual interference for vehicle identification and classification and executes automated tracking of the ident...
Article
Full-text available
For many decades automated sensors, such as acoustic, optical, pneumatic, magnetic, inductive sensors and video-based image processing solutions were used for collecting data on traffic flow, speed, density, travel time etc. Using these data, the level of congestion is indirectly estimated. However, most of these sensors are costly and location-bas...
Article
Travel time information assists road users in making informed travel decisions such as mode choice, route choice and/or time of travel. This study explores the use of GPS data from buses and Wi-Fi and Bluetooth data from a sample of vehicles, for accurate estimation of the travel time of all vehicles on the roadway. A 5.5 km road stretch in Chennai...
Article
Mobility of the road network is a serious problem which traffic managers all over the world are trying to resolve. India is one of the populous countries in the world. Most of the arterial and local roads of India remain highly congested causing unbearable delays; thus affecting the mobility. Addressing the mobility issues and analyzing performance...
Article
Full-text available
Limited studies are conducted to develop trajectory-level data extraction tools for non-lane-based heterogeneous traffic conditions prevalent in developing countries, like India. Comprehending this research gap, the development of an automation-based conceptual methodology is crucial, that would help researchers to understand and assess heterogeneo...
Article
Dynamic scheduling of buses, which adapts to the current passenger demand and traffic conditions, will help in ensuring an efficient service to the commuters and maximizing the profit for operators. A fixed schedule with a constant headway, which is currently used widely, may lead to inadequate number of buses during peak periods and under-utilizat...
Article
Public transport buses have uncertainties associated with its arrival/travel times, due to several factors such as signals, dwell times at bus stops, seasonal variations, fluctuating travel demands, and so on. In the developing world, these uncertainties are further magnified by the presence of excess vehicles, diverse modes of transport, and acute...
Preprint
Providing real time information about the arrival time of the transit buses has become inevitable in urban areas to make the system more user-friendly and advantageous over various other transportation modes. However, accurate prediction of arrival time of buses is still a challenging problem in dynamically varying traffic conditions especially und...
Conference Paper
In this paper, a model based estimation scheme has been proposed to estimate density incorporating the heterogeneity and lane indiscipline observed in Indian traffic. In order to incorporate lane indiscipline, the road stretch under study was considered as multiple parallel strips. Time occupancy and composition based weighted vehicle length were u...
Article
Vehicle classification has a prominent role in intelligent transportation systems (ITS) for traffic management and monitoring for various applications. One such application is the automated toll collection system. Here, the vehicles need to be accurately classified and verified, as the tolling amount depends on the vehicle type. There are several s...
Article
Inductive loop detectors (ILDs) are one of the most widely deployed traffic sensors. At present, for lane-by-lane detection, ILDs require separate connecting cables for each loop (each lane) and separate data acquisition systems or detector channels to process them. This becomes problematic with limited conduit and cabinet space. In most cases, tra...
Conference Paper
Full-text available
With rising traffic congestion on the Indian roadways, development of effective traffic control measures is gaining attention. An effective traffic control measure is the one which reduces delay and increases the travel time reliability. To achieve this, accurate estimation of delay is very critical. Generally, this would involve the deployment of...
Article
Providing accurate and reliable travel time information to travellers is essential to improve the quality of public transit systems. With the availability of the latest technologies, it has become possible to collect a large amount of traffic data to analyze and understand these systems better. Traffic in India is characterized by lack of lane disc...
Article
The phenomenon of platoon dispersion deals with the spreading out of groups of vehicles discharged together from a signal (platoon) as they move along the roadway during normal traffic operations. Understanding and analyzing this behavior is important in efficient traffic operations and management. There are different platoon dispersion models repo...
Article
Full-text available
Travel time is one of the most appropriate traffic measures that can be provided to road users for easy understanding and decision making. This paper presents a simple method to predict travel time on urban arterial roads. Travel time prediction methods include historical methods, model based methods, and data driven approaches. Of these, data driv...
Article
Road traffic congestion has become a global worry in recent years. In many countries congestion is a major factor, causing noticeable loss to both economy and time. The rapid increase in vehicle ownership accompanied by slow growth of infrastructure has resulted in space constraints in almost all major cities in India. To mitigate this issue, autho...
Conference Paper
Road traffic congestion has become a global worry in recent years. In many countries, congestion have spawn as a major factor, causing noticeable loss to both economy and time. The rapid increase in vehicle ownership accompanied by slow growth of infrastructure has resulted in space constraints in almost all major cities in India. To mitigate this...
Conference Paper
Full-text available
Inductive loop detectors (ILD) are one of the most popular traffic detectors in use. It works based on the principle of mutual inductance and detects vehicles by measuring the change in inductance due to its presence on top of the sensor. The change in voltage measured is usually called as vehicle signature and is the raw output from the detector s...
Article
Providing accurate information about bus arrival time to passengers can make public transport system more attractive. Such information helps the passengers by reducing the uncertainty on waiting time and the associated frustrations. However, accurate estimation of bus travel time is still a challenging problem, especially under heterogeneous and la...
Article
Predicting bus arrival times and travel times are crucial elements to make the public transport more attractive and reliable. The present study explores the use of Intelligent Transportation Systems (ITS) to make public transportation systems more attractive by providing timely and accurate travel time information of transit vehicles. However, for...
Article
Full-text available
Accurate travel time information of public transport will help operators to effectively manage and implement their operating strategies and help passengers by reducing the uncertainty about arrival time of buses at bus stops. The reliability of such information provided to passengers greatly depends on the prediction technique used, which in turn,...
Article
The accuracy of travel time information given to passengers plays a key role in the success of any Advanced Public Transportation Systems (APTS) application. In order to improve the accuracy of such applications, one should carefully develop a prediction method. A majority of the available prediction methods considered the variation in travel time...
Article
Full-text available
In recent times, traffic congestion has been increasing rapidly and deteriorating the quality of traffic systems in urban areas of many developed and developing countries. This became a serious problem faced by society, as many people are using private vehicles while commuting from one place to the other. One of the reasons people are shifting towa...
Article
Road traffic congestion, which occurs when the traffic demand exceeds the operational capacity of the roadway, has become a serious problem all over the world. Traffic signals are effective in managing the traffic demand if properly designed. Traditionally, signal design has been carried out based on the objective of minimizing the overall queue an...
Article
In recent times, bus arrival time prediction (BATP) systems are gaining more popularity in the field of advanced public transportation systems, a major functional area under intelligent transportation systems. BATP systems aim to predict bus arrival times at various bus stops and provide the same to passenger’s pre-trip or while waiting at bus stop...
Article
Full-text available
Analysis of traffic at a signalized intersection requires quantification of the number of vehicles in the queue and the corresponding delay. Such analyses can be used for optimal signal control as well as for intelligent transportation system (ITS) applications such as advanced traveler information systems (ATISs). However, the direct measurement o...
Article
Capturing real-time traffic system characteristics is a primary step in any intelligent transportation system (ITS) application. The majority of the traffic sensors used to capture real-time data have been developed for homogeneous and lane-disciplined traffic conditions. Hence many of them may not perform accurately under heterogeneous and less-la...
Article
Traffic density is an indicator of congestion and the present study explores the use of data-driven techniques for real time estimation and prediction of traffic density. Data-driven techniques require large database, which can be achieved only with the help of automated sensors. However, the available automated sensors developed for western traffi...
Article
Full-text available
Predicting and providing information about bus arrival time to passengers accurately is a very important aspect of advanced public transportation systems (APTS), a major functional area of intelligent transportation systems. However, the information provided to passengers should be reliable. The reliability of such information provided to passenger...
Article
Macroscopic model-based schemes are appropriate for real-time estimation of traffic density, which is an important congestion indicator. Conservation of vehicles equation is one of the basic equations used in any macroscopic model-based analysis. However, to apply the conservation equation, accurate flow/count data should be available, which can be...
Article
Full-text available
Urbanization and gro wing demand for travel, causes the traffic system to work ineffectively in most urban areas leadin g to traffic congestion. Many approaches have been adopted to address this problem, one among them being the signal co-ordination. This can be achieved if the platoon of vehicles that gets discharged at one signal gets green at co...
Article
Full-text available
Advanced Traveller Information Systems (ATIS) is one of the functional areas of Intelligent Transportation Systems (ITS) and it aims at providing real time traffic information to the travellers for making better travel decisions. This information would be most effective if provided to travellers during or before the start of their trip. Therefore,...
Article
Full-text available
Headway is a microscopic parameter of traffic flow and is defined as the temporal or spatial distance between two consecutive vehicles. On a macroscopic level these headways translate to density and flow, which are two of the fundamental traffic flow parameters. Several studies were reported on headway patterns and the distribution followed by head...
Poster
Full-text available
Bus Travel Time Prediction using Artificial Neural Networks (ANNs), Support Vector Machines (SVMs), and Classification schemes.
Article
This study presents a methodology for travel-time prediction on urban arterial networks using data from global positioning system (GPS) probe vehicles, under Indian traffic conditions. Given any link in the network, the model predicts its travel time on the basis of historic patterns and real-time information. By doing this, it would be possible to...
Article
Developments in the area of intelligent transportation system in India are constrained due to the difficulty in accurate automated data collection. Many existing automated sensors may not be accurate under Indian traffic conditions due to their heterogeneity and less lane discipline, resulting in erroneous data. Thus, there is a need to develop too...
Article
Bus travel times are prone to high variability, especially in countries that lack lane discipline and have heterogeneous vehicle profiles. This leads to negative impacts such as bus bunching, increase in passenger waiting time and cost of operation. One way to minimize these issues is to accurately predict bus travel times. To address this, the pre...
Article
Travel-time information is an integral part of Advanced Traveler Information Systems and Advanced Traffic Management Systems. Real-time estimation of stream travel time will be helpful in making trip decisions such as route choice and departure time. The present study proposes a method to predict stream travel time using particle filtering approach...
Article
The travel decisions made by road users are more affected by the traffic conditions when they travel than the current conditions. Thus, accurate prediction of traffic parameters for giving reliable information about the future state of traffic conditions is very important. Mainly, this is an essential component of many advanced traveller informatio...