Showing papers by "Gitakrishnan Ramadurai published in 2010"

Linear Complementarity Formulation for Single Bottleneck Model with Heterogeneous Commuters

Abstract: 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 established complementarity theory and methods to analyze the model, and providing a significant contribution to the existing literature that either lacks a rigorous formulation or solves the problem under a limited set of heterogeneity parameter assumptions. The paper presents theoretical proofs for solution existence and uniqueness, and numerical results and insights for different heterogeneity assumptions.

Dynamic user equilibrium model for combined activity-travel choices using activity-travel supernetwork representation

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.

On the Existence of Pricing Strategies in the Heterogeneous Single Bottleneck Model

Abstract: Since the single bottleneck with homogeneous and heterogeneous commuters was formulated as a linear complementarity problem (LCP), it has enabled the research community to look at important extensions. Based on the LCP formulations, this paper will explore useful extensions to contribute to the single bottleneck literature. First, the congestion pricing for homogeneous and heterogeneous commuters is studied. This paper shows that the system optimal for single bottleneck model with heterogeneous commuters might be obtained by an appropriate pricing scheme. Second, the models with flexible arrival time for both homogeneous and heterogeneous models are formulated. It is shown that the system optimal for heterogeneous commuter model might be obtained with a proper toll scheme. Finally, the LCP formulation is extended to study the elastic capacity problem for the homogeneous case. The result shows that, in the particular condition, the existence and uniqueness for homogeneous model with elastic capacity can be guaranteed.