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Gitakrishnan Ramadurai

Bio: Gitakrishnan Ramadurai is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Traffic flow & Bottleneck. The author has an hindex of 17, co-authored 61 publications receiving 1108 citations. Previous affiliations of Gitakrishnan Ramadurai include Rensselaer Polytechnic Institute & Indian Institutes of Technology.


Papers
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Journal ArticleDOI
TL;DR: A Kalman filter is used to fuse spatial and location-based data for the estimation of traffic density and the models performed well, despite the challenges arising from heterogeneous traffic flow conditions prevalent in India.

70 citations

Journal ArticleDOI
TL;DR: In this article, the authors jointly modeled activity location, time of participation, duration, and route choice decisions in a single unified dynamic framework referred to as Activity-Travel Networks (ATNs), where virtual links representing activity choices are added to augment the travel network to represent additional choice dimensions.
Abstract: 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, time of participation, duration, and route choice decisions are jointly modeled in a single unified dynamic framework referred to as Activity-Travel Networks (ATNs). ATNs is a type of Supernetwork where virtual links representing activity choices are added to augment the travel network to represent additional choice dimensions. Each route in the augmented network represents a set of travel and activity arcs. Therefore, choosing a route is analogous to choosing an activity location, duration, time of participation, and travel route. A cell-based transmission model (CTM) is embedded to capture the traffic flow dynamics. The dynamic user equilibrium (DUE) behavior requires that all used routes (activity-travel sequences) provide equal and greater utility compared to unused routes. An equivalent variational inequality problem is obtained. A solution method based on route-swapping algorithm is tested on a hypothetical network under different demand levels and parameter assumptions.

67 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed representative driving cycles for passenger cars and motorcycles which reflect the real-world driving conditions in Chennai, India, using on-board diagnostic (OBD) reader and Global Positioning System (GPS) receivers.

65 citations

Journal ArticleDOI
TL;DR: A three-index formulation for E-VRP with Non-Linear charging and Load-Dependent discharging, and an Adaptive Large Neighborhood Search (ALNS) algorithm to solve the E- VRP-NL- LD and E-RLLD with Capacitated Charging Stations, which shows that considering load-dependent discharge is critical to optimally solve E-vrP optimally.
Abstract: 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 enables the modelling of EVRP using extended VRP formulations. Two limitations of such an approach are: (i) the number of such duplications is not known a priori, and (ii) the size of the problem increases. In our formulation, we allow multiple visits to a charging station without duplicating nodes. We propose five new operators for ALNS which are tested on 120 instances each of E-VRP-NL and E-VRP-NL-LD, and 80 instances of E-VRP-NL-LD-CCS. Results show that our ALNS outperforms the existing algorithms improving the solution in 63% of the instances and matching the best known solution in 31% of the instances. Results also show that considering load-dependent discharge is critical to optimally solve E-VRP optimally.

53 citations

Journal ArticleDOI
TL;DR: An existing second-order continuum model of traffic flow is extended, using area occupancy for traffic concentration instead of density, to suggest area occupancy as concentration measure of heterogeneous traffic lacking in lane discipline.

53 citations


Cited by
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11 Feb 2010
TL;DR: The American Community Survey (ACS) as discussed by the authors has been conducted on an ongoing basis for the entire country since 2005 and has been shown to be more accurate than the traditional decennial census.
Abstract: Historically, most demographic data for states and substate areas were collected from the long version of the decennial census questionnaire. A “snapshot” of the characteristics of the population on the April 1 census date was available once every 10 years. The long form of the decennial census has been replaced by the American Community Survey (ACS) that has been conducted on an ongoing basis for the entire country since 2005. Instead of a snapshot in which all of the data are gathered at one time, the ACS aggregates data collected over time, making the results more difficult to interpret. However, the ACS data are updated annually.

691 citations

Book
01 Jan 1997
TL;DR: This book presents a coherent approach to the analysis of transportation networks based on the concept of network equilibrium and the application of convex programming methods, and indicates promising areas for further research.
Abstract: Transportation Networks. Optimality. Cost Functions. Deterministic User Equilibrium Assignment. Stochastic User Equilibrium Assignment. Trip Table Estimation. Network Reliability. Network Design. Conclusions. References. Index.

584 citations

Journal ArticleDOI
TL;DR: In this paper, a linear programming formulation for autonomous intersection control (LPAIC) is proposed to account for traffic dynamics within a connected vehicle environment, where a lane based bi-level optimization model is introduced to propagate traffic flows in the network, accounting for dynamic departure time, dynamic route choice, and autonomous intersections control in the context of system optimum network model.
Abstract: This paper develops a novel linear programming formulation for autonomous intersection control (LPAIC) accounting for traffic dynamics within a connected vehicle environment. Firstly, a lane based bi-level optimization model is introduced to propagate traffic flows in the network, accounting for dynamic departure time, dynamic route choice, and autonomous intersection control in the context of system optimum network model. Then the bi-level optimization model is transformed to the linear programming formulation by relaxing the nonlinear constraints with a set of linear inequalities. One special feature of the LPAIC formulation is that the entries of the constraint matrix has only {−1, 0, 1} values. Moreover, it is proved that the constraint matrix is totally unimodular, the optimal solution exists and contains only integer values. It is also shown that the traffic flows from different lanes pass through the conflict points of the intersection safely and there are no holding flows in the solution. Three numerical case studies are conducted to demonstrate the properties and effectiveness of the LPAIC formulation to solve autonomous intersection control.

216 citations