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Karthikgeyan Sivakumarana

Bio: Karthikgeyan Sivakumarana is an academic researcher. The author has contributed to research in topics: Cost effectiveness & Schedule. The author has an hindex of 1, co-authored 1 publications receiving 46 citations.

Papers
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01 Aug 2010
TL;DR: In this article, an idealized system that delivers its users to a common destination by requiring each to transfer from a feeder to a trunk-line vehicle is considered, and it is shown that coordination can be Pareto improving, meaning that operator and user costs both diminish.
Abstract: Coordination of vehicle schedules in a public transit system affects generalized costs. An idealized system that delivers its users to a common destination by requiring each to transfer from a feeder to a trunk-line vehicle is considered. Continuum models are used first to analyze cases in which the trunk-line vehicle schedule is given exogenously. When feeder vehicles are dispatched in coordination with this exogenous trunk-line schedule, the reduction in user cost often outweighs the added cost to the feeder operation. In cases when the frequencies of trunk and feeder services can be established jointly, the models show that coordination can be Pareto improving, meaning that operator and user costs both diminish. Conditions that give rise to these cost savings are specified. Practical implications are discussed.

53 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors present a comprehensive review of the literature on transit network planning problems and real-time control strategies suitable for bus transport systems, emphasizing recent studies as well as works not addressed in previous reviews.
Abstract: The efficiency of a transport system depends on several elements, such as available technology, governmental policies, the planning process, and control strategies. Indeed, the interaction between these elements is quite complex, leading to intractable decision making problems. The planning process and real-time control strategies have been widely studied in recent years, and there are several practical implementations with promising results. In this paper, we review the literature on Transit Network Planning problems and real-time control strategies suitable to bus transport systems. Our goal is to present a comprehensive review, emphasizing recent studies as well as works not addressed in previous reviews.

476 citations

Journal ArticleDOI
TL;DR: The results show that the metro network resilience to disruptions can be enhanced significantly from localized integration with public bus services, and this approach is applied to a case study based on the Singapore public transit system and actual travel demand data.
Abstract: This paper advances the field of network disruption analysis by introducing an application to a multi-modal transport network, capitalizing on the redundancies and improved connectivity of an integrated metro-bus network. Metro network resilience to disruptions can be enhanced by leveraging on public bus services. To ensure better acceptance among operators and commuters, we focus on introducing localized integration with bus services instead of designing an entirely new bus network to achieve the desired resilience to potential disruptions. This is accomplished by increasing the capacity of bus services that run in parallel with affected metro lines as well as those connecting to different metro lines. Our analysis starts with a network representation to model the integrated metro and bus system. A two-stage stochastic programming model is further developed to assess the intrinsic metro network resilience as well as to optimize the localized integration with bus services. The approach is applied to a case study based on the Singapore public transit system and actual travel demand data. The results show that the metro network resilience to disruptions can be enhanced significantly from localized integration with public bus services.

202 citations

Journal ArticleDOI
TL;DR: Results show that when the rerouting behaviour is considered, more cost-effective schedule coordination scheme with less slack times can be achieved, and ignoring such effect would underestimate the efficacy ofdule coordination scheme.
Abstract: Schedule coordination is a proven strategy to improve the connectivity and service quality for bus networks, whereas current research mostly optimizes schedule design using the a priori knowledge of users’ routings and ignores the behavioural reactions to coordination status. This study proposes a novel stochastic bus schedule coordination design with demand assignment and passenger rerouting in case of transfer failure. To this end, we develop a bi-level programming model in which the schedule design (headways and slack times) and passenger route choice are determined simultaneously via two travel strategies: non-adaptive and adaptive routings. In the second strategy, transfer passengers would modify their paths in case of missed connection. In this way, the expected network flow distribution is dependent on both the transfer reliability and network structure. The upper-level problem is formulated as a mixed integer non-linear program with the objective of minimizing the total system cost, including both operation cost and user cost, while the lower-level problem is route choice (pre-trip and on-trip) model for timed-transfer service. A more generalized inter-ratio headways scenario is also taken into account. A heuristic algorithm and the method of successive averages are comprehensively applied for solving the bi-level model. Results show that when the rerouting behaviour is considered, more cost-effective schedule coordination scheme with less slack times can be achieved, and ignoring such effect would underestimate the efficacy of schedule coordination scheme.

96 citations

Journal ArticleDOI
TL;DR: In this article, a bi-objective, bi-level integer programming model was developed to solve the problem of timetable synchronization in public transport systems, taking into account the interests of public transport users and operators.
Abstract: In the operations planning process of public transport (PT), timetable synchronization is a useful strategy utilized to reduce transfer waiting time and improve service connectivity. However, most of the studies on PT timetable synchronization design have treated the problem independently of other operations planning activities, and have focused only on minimizing transfer waiting time. In addition, the impact of schedule changes on PT users’ route/trip choice behavior has not been well investigated yet. This work develops a new bi-objective, bi-level integer programming model, taking into account the interests of PT users and operators in attaining optimization of PT timetable synchronization integrated with vehicle scheduling and considering user demand assignment. Based on the special structure characteristics of the model, a novel deficit function (DF)-based sequential search method combined with network flow and shifting vehicle departure time techniques is proposed to achieve a set of Pareto-efficient solutions. The graphical features of the DF can facilitate a decision-making process for PT schedulers for finding a desirable solution. Two numerical examples are illustrated to demonstrate the methodology developed.

80 citations

Journal ArticleDOI
TL;DR: Comparing the results obtained by the proposed Memetic algorithm and traditional algorithms which have been proved to be efficient, it demonstrates that the proposed algorithm could improve the computational performance relative to other algorithms.
Abstract: The Memetic algorithm to optimize the urban transit network is proposed.Four types of local search operators to improve the performance are designed.The proposed algorithm is tested to improve the performance to other algorithms.Some interesting issues for the transit network are analyzed and discussed. This paper employs the Memetic algorithm (MA) to optimize the urban transit network. Aiming at the optimal route configuration and service frequency for the urban transit network, the objective function of the proposed mathematical model is to minimize the passenger (user) cost and to reduce the unsatisfied passenger demand at most. MA is one of the recent growing evolutionary computation algorithms. It is imbedded with the local search operator based on the classical genetic algorithm (GA) to improve the computational performance. We represent the solution with two single link lists (SLL), and design four types of local search operators: 2-opt move (Type A), 2-opt move (Type B), swap move and relocation move to obtain the better chromosomes for the GA. At the same time, an effective try-an-error procedure for verifying the local search operator is presented to increase the search efficiency. The algorithm has been tested with benchmark problems reported in the existing literatures. Comparing the results obtained by our algorithm and traditional algorithms which have been proved to be efficient, it demonstrates that the proposed algorithm could improve the computational performance relative to other algorithms.

71 citations