Gitakrishnan Ramadurai

Gitakrishnan Ramadurai
Indian Institute of Technology Madras | IIT Madras · Department of Civil Engineering

About

67
Publications
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1,326
Citations

Publications

Publications (67)
Article
This study presents an integrated model to shed light on the factors influencing individuals’ likelihood and frequency of usage of bus transit in Bengaluru, India, with a focus on the role of individuals’ subjective perceptions of service quality. Typically, subjective perceptions of transit service characteristics such as comfort, cleanliness, rel...
Article
Estimating emissions savings from alternative vehicular technologies is essential to streamline urban freight transport policy. We estimate freight emissions in the city of Chennai, India using real-world emission factors obtained from on-board emission measurement systems and trip characteristics collected through an establishment survey. India re...
Article
Many rapidly developing countries around the world are at a crossroads when it comes to transportation, air quality, and sustainability. Indeed, the challenges presented by vehicular growth in India have motivated the search for sustainable transportation solutions. One solution constitutes ridehailing services, which are expected to reduce car own...
Article
During the last two decades, there has been substantial interest in developing freight trip generation (FTG) models. Most studies consider only truck trips or convert all freight trips into equivalent truck trips. Freight in several large cities is increasingly being moved by smaller vehicles. This calls for modeling FTG by vehicle type. The presen...
Article
Full-text available
This paper formulates a spatial autoregressive zero-inflated negative binomial model for freight trip productions and attractions. The model captures the following freight trip characteristics: count data type, positive trip rates, overdispersion, zero-inflation, and spatial autocorrelation. The spatial autoregressive structure is applied in the ne...
Article
In this study, researchers have explored real-world driving conditions and developed emission factors for 58 passenger cars using on-board emission measurement technique while driving on five different routes in Delhi. The measured average emission factors of CO, HC, and NO were 3.99, 0.34, and 0.54 g/km for diesel vehicles, 7.26, 0.17, and 0.62 fo...
Article
This paper proposes a continuum model based on a three-dimensional flow-concentration surface for multi-class traffic. The model assumes that the flow of any vehicle class is a function of the class density as well as the fraction of road area occupied by other vehicle classes. By considering occupancy of road area instead of lane occupancy, the mo...
Article
Ride-hailing services have grown in cities around the world. There are, however, few studies and even fewer publicly available data sources that provide a basis to understand and quantify changes in ride-hailing usage over time. Ride-hailing use may change over time because of socio-demographic shifts, economic and technological changes, and servic...
Article
Full-text available
We propose a three-index formulation for E-VRP with Non-Linear charging and Load-Dependent discharging (E-VRP-NL-LD), and an Adaptive Large Neighborhood Search (ALNS) algorithm to solve the E-VRP-NL-LD and E-VRP-NL-LD with Capacitated Charging Stations (E-VRP-NL-LD-CCS). Existing implementations of EVRP duplicate charging station nodes which enable...
Article
Full-text available
Although urban freight transport is a significant contributor to the development of a country, it has adverse effects on the environment and the quality of life in urban areas. To reduce these adverse effects, we can deploy sustainable city logistic strategies. Scheduling and routing of vehicles is a crucial decision in city logistic strategies. He...
Article
Full-text available
Multi‐class traffic flow modelling has various approaches several of which have focused on analytical proofs. A key limitation in this field of research is the limited field data applications. This study proposes a speed‐gradient‐based multi‐class second‐order model and shows its application to three different road sections, a mid‐block section, a...
Article
Introduction Personal exposure to elevated vehicle exhaust and non-exhaust emissions at urban roadside leads to carcinogenic health effects, respiratory illness and nervous system disorders. In this paper, an attempt has been made to investigate the exhaust and non-exhaust emissions emitted from selected roads in Delhi city. Methods Based on the v...
Article
The virtual (online) and physical (in-person) worlds are increasingly inter-connected. Although there is considerable research into the effects of information and communication technologies (ICT) on activity-travel choices, there is little understanding of the inter-relationships between online and in-person activity participation and the extent to...
Article
We present a complex weighted network analysis of a bus transport network. We model the network as graphs in L-space and P-space and evaluate the statistical properties in unweighted and weighted cases. The weights considered include number of overlapping routes and passenger demand between two bus stops. We also introduce a new supply-based edge w...
Article
The introduction of mobile application-based ride hailing services represents a convergence between technologies, supply of vehicles, and demand in near real time. There is growing interest in quantifying the demand for such services from regulatory, operational, and system evaluation perspectives. Several studies model the decision to adopt ride h...
Chapter
Emissions from motor vehicles lead to significant adverse effect on air quality of cities, with many cities reporting ambient air concentration of pollutants well beyond the permissible standards. In this paper, we determine the effect of changing driving patterns during peak and off-peak periods on emissions from diesel passenger cars. Second-by-s...
Chapter
Transit networks are essentially temporal with their topology evolving over time. While there are several studies on the topological properties of bus transit networks, none of them have captured the temporal network characteristics. We present a temporal analysis of a bus transit network using snapshot representation. We propose a supply-based wei...
Article
Full-text available
Driving cycles are used to understand the driving pattern of vehicles and in estimating their emissions. Although several studies exist on driving cycles worldwide, few studies have focused on developing driving cycles for intra-city buses in heterogeneous traffic conditions. In this study, driving cycles for intra-city buses were developed using r...
Poster
Full-text available
This paper presents an exploratory study at an industrial estate in Chennai to understand the freight transport characteristics and the scope and the need for freight consolidation.
Article
Motor vehicles contribute significantly to the total emissions in a city. Several studies have attempted to quantify emissions from cars, buses, and trucks using laboratory-based or real-world emission tests. However, real-world emissions from motorcycles (or motorized two-wheelers) has not received adequate attention. Unlike developed countries wh...
Article
Full-text available
We formulate the two-echelon routing problem considering multiple depots and heterogeneous fleets. Our study (a) presents a Mixed Integer Linear Programming (MILP) formulation with load-dependent fuel minimization objective, (b) uses driving cycles to represent speed variations along a path, (c) allows the vehicles to return to any depot/satellite,...
Article
Full-text available
Heterogeneous traffic as observed in several south Asian countries is characterized by complex interactions of widely varying vehicle types that do not follow lanes and with smaller vehicles filling any gaps available. This paper discusses on four main components of macroscopic simulation of traffic flow in the Indian traffic context. One of the pr...
Conference Paper
This paper presents the characteristics of exhaust and non-exhaust emissions measured at selected roads in Delhi city. The real-world exhaust emissions were measured in car using AVL Digest 1000 analyser. The silt load measurements were carried out as per EPA AP-42 methodology. Results indicated that the real-world exhaust emissions were higher in...
Conference Paper
Urban freight movement is vital for the economy of a city and nation. However, freight transport has a significant share in causing noise pollution, traffic congestion, and global warming leading to adverse health effects. Freight emission modelling typically uses data collected from laboratory-based vehicle emission tests. In a lab test, the impac...
Article
Diesel trucks contribute significantly to emissions leading to deterioration in urban air quality. Many recent studies have attempted to quantify real-world emissions from trucks in cities. However, studies on real-world emission from trucks in India are scarce. In this study, we measured real-world emissions of gaseous pollutants (CO, HC, and NO)...
Article
Full-text available
Electric vehicles are gaining popularity day-by-day aided by growing pollution concerns with fossil fuel vehicles. Many logistics companies have already started testing electric vehicles for deliveries in cities. However, electric vehicles have issues such as range anxiety and long recharge times. These issues have to be considered in routing elect...
Article
Passenger cars contribute significant emissions in urban areas affecting the air quality of cities. Traditionally, vehicular emission factors (EFs) were developed based on measurements in the laboratory. However, studies indicate that the laboratory measurements are unrepresentative of real-world conditions. In this study, EFs were developed for di...
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
Full-text available
Traditionally, vehicle routing problems (VRP) were solved with the objective of minimizing total distance traveled. The rationale behind minimizing distance was perhaps that fuel consumption depends on distance traveled. Fuel consumption depends on several other factors besides distance. Recently, several authors have focused on directly minimizing...
Article
Road transport is a significant contributor of pollutant emissions in the cities of developing countries. Driving cycles are required for the estimation of fuel consumption and exhaust emissions from vehicles for emission testing and certification, with many cities having unique cycles for different types of vehicles and roads. However, no driving...
Article
Full-text available
Intra-city buses provide essential transportation and mobility services in cities. However, most of the buses in Indian cities run on diesel fuel causing significant emissions and air quality issues. This study aims to quantify the emissions from the buses during peak and off-peak periods using second-by-second activity data collected using global...
Article
Modelling heterogeneous traffic flow lacking in lane discipline is one of the emerging research areas in the past few years. The two main challenges in modelling are: capturing the effect of varying size of vehicles, and the lack in lane discipline, both of which together lead to the ‘gap filling’ behaviour of vehicles. The same section length of t...
Article
Full-text available
Discharge headway is the headway between successive vehicles negotiating an intersection during the green time of signal oper- ation. It is an important parameter in signal operations and analysis since estimation of parameters such as saturation flow and capacity of an intersection depend on it. Although there have been several studies on discharg...
Article
Full-text available
Bus transportation is considered as one of the most convenient and cheapest modes of public transportation in Indian cities. Due to their cost-effectiveness and wide reachability, they help a significant portion of the human population in cities to reach their destinations every day. Although from a transportation point of view they have numerous a...
Article
Full-text available
Through the past decade the field of network science has established itself as a common ground for the cross-fertilization of exciting inter-disciplinary studies which has motivated researchers to model almost every physical system as an interacting network consisting of nodes and links. Although public transport networks such as airline and railwa...
Article
Full-text available
In this paper, we study the structural properties of the complex bus network of Chennai. We formulate this extensive network structure by identifying each bus stop as a node, and a bus which stops at any two adjacent bus stops as an edge connecting the nodes. Rigorous statistical analysis of this data shows that the Chennai bus network displays sma...
Article
Most Indian cities face oversaturated flow conditions during peak periods. In this paper we revisit the traffic signal control to improve urban network performance. Three novel strategies that address congested heterogeneous traffic flow are presented. The first two strategies - keeping intersection signal cycle times shorter and bottleneck meterin...
Article
The paper presents a fast algorithm for real-time image processing for counting and classification of vehicles in heterogeneous traffic recorded using a single stationary camera. The proposed method uses a single feature as the base parameter which is given by the user to classify the vehicles into four different classes. The algorithm has an error...
Article
Traffic congestion has become a major challenge in recent years in many countries of the world. One way to alleviate congestion is to manage the traffic efficiently by applying intelligent transportation systems (ITS). One set of ITS technologies helps in diverting vehicles from congested parts of the network to alternate routes having less congest...
Article
Full-text available
An accurate Dynamic Traffic Assignment (DTA) model should capture real world traffic flow dynamics and predict ‘dynamic’ travel times. Traditional DTA models used simple traffic flow functions such as exit flow functions, delay functions, point queues, and deterministic physical queue models. Recently, simulation based models apply well accepted tr...
Conference Paper
Full-text available
Efficient modeling of vehicular traffic remains a largely debated issue especially in context of Indian heterogeneous driving conditions. VISSIM is a microscopic traffic simulation software that is gaining increasing recognition in India. However, modifications to the default behavioral parameters are essential to effectively simulate Indian hetero...
Article
Full-text available
Modelling heterogeneous traffic flow for Asian countries is one of the emerging research areas in the past few years. The two main challenges in modelling are: capturing the effect of varying size of vehicles, and the lack in behavior of vehicles. The same section length of the road can be occupied by different types of vehicles at the same time, a...
Article
Full-text available
Macroscopic traffic flow models are suited for large scale, network wide applications where the macro-characteristics of the flow are of prime interest. A clear understanding of the existing macro-level traffic flow models will help in modelling of varying traffic scenarios more accurately. Existing state-of-the-art reports on traffic flow models h...
Article
This paper formally introduces a linear complementarity system (LCS) formulation for a continuous-time, multi-user class, dynamic user equilibrium (DUE) model for the determination of trip timing decisions in a simplified single bottleneck model. Existence of a Lipschitz solution trajectory to the model is established by a constructive time-steppin...
Article
This study investigates (i) the link of land use and road design on pedestrian safety and (ii) the effect of the level of spatial aggregation on the frequency of pedestrian accidents. For this purpose, pedestrian accident frequency models were developed for New York City based on an extensive dataset collected from different sources over a period o...
Article
Multi-dimensional choice in dynamic traffic assignment (DTA)—for example, a combined model of activity location, time of participation, duration, and route choice decisions—results in exponentially increasing choice alternatives. Any efficient algorithm for solving the multi-dimensional DTA problem must avoid enumeration of alternatives. In this ar...
Article
Full-text available
Integrated urban transportation models have several benefits over sequential models including consistent solutions, quicker convergence, and more realistic representation of behavior. Static models have been integrated using the concept of Supernetworks. However integrated dynamic transport models are less common. In this paper, activity location,...
Article
Transportation system analysis must rely on predictions of the future that, by their very nature, contain substantial uncertainty. Future demand, demographics, and network capacities are only a few of the parameters that must be accounted for in both the planning and every day operations of transportation networks. While many repercussions of uncer...
Article
This paper formulates the dynamic equilibrium conditions for a single bottleneck model with heterogeneous commuters as a linear complementarity problem. This novel formulation offers a formal framework for the rigorous study and solution of a single bottleneck model with general heterogeneity parameter assumptions, enabling the adoption of well est...
Article
The New York Metropolitan Transportation Council (NYMTC) funded a project executed by a team from Rensselaer Polytechnic Institute to perform a comprehensive scan of emerging technologies that could affect transportation in the New York City metropolitan region in the next 20 years. A primary goal of the technology scan is to develop a document tha...
Article
This study analyzes changes in sociodemographic, activity, land use, and mobility patterns and their effects on travel dimensions in the context of a developing country. More specifically, increase in vehicle ownership (both two-wheelers and cars) and changes in mode choice over time are observed and analyzed with the use of household data from Che...
Article
Full-text available
The existence of equilibrium solutions in single-bottleneck models with homogeneous travelers having the same preferred arrival times is explored from both theoretical and experimental frameworks. First, an equal payoff solution obtained in past studies is proved not to be in dynamic user equilibrium (DUE). Necessary conditions for DUE are presente...
Article
This research investigated within-day dynamics and variations in mode choice within and across individuals at the activity-episode level. Specifically, dynamics and variability were examined at four levels: (a) effect of variation over time of explanatory attributes such as episode-trip characteristics, (b) influence of state-dependence (past choic...
Article
This research investigated within-day dynamics and variations in mode choice within and across individuals at the activity-episode level. Specifically, dynamics and variability were examined at four levels: (a) effect of variation over time of explanatory attributes such as episode–trip characteristics, (b) influence of state-dependence (past choic...

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