Browsing by Author "Kuvvetli, Umit"

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Citation - WoS: 14
Citation - Scopus: 19
Deadhead Trip Minimization in City Bus Transportation: a Real Life Application
(Svenciliste U Zagrebu, Fakultet Prometnih Znanosti, 2013) Nasibov, Efendi; Eliiyi, Ugur; Ertac, Mefharet Ozkilcik; Kuvvetli, Umit
The quality of public transportation services is one of the most important performance indicators of modern urban policies for both planning and implementation aspects. Therefore, along with the size of the city, the significance of appropriate cost evaluation and optimization of all related transportation activities increases as well. One of the most important cost factors for the public transport agencies is naturally the fuel consumption of the vehicles. In this study, the attention is focused on the metropolitan bus transport service. The specific aim is to minimize a significant portion of total fuel utilization that occurs due to the so called deadhead trip or dead mileage, which is defined as the idle distance covered by the vehicle between the garage and the route terminal stops without carrying any passengers. In this study, the results of four mathematical models for minimizing the total deadhead trip distance covered in city bus services of Izmir are presented. The models vary due to the inclusion of garage capacity restrictions or operator distinction for supporting both operational and strategical decisions. All models are applied to the recent bus schedule data, which consist of 293 routes, 1,424 buses and 10 garages, for obtaining the optimal route bus-garage allocations and garage capacities. The results of the Decentralized-Capacitated model, which is appropriate for quick implementation, promise a 7.8% reduction in total dead mileage. While on the other hand, if all garage capacities can be expanded and the bus service is maintained only by one operator as modelled in the Centralized-Uncapacitated case, even a 31.4% improvement is possible in the long term. The environmental gains as well as the financial benefits to be achieved when the solutions are actually implemented, justify the practical contribution of the study.
Citation - WoS: 9
Minimization of Fuel Consumption in City Bus Transportation: a Case Study for Izmir
(Elsevier Science Bv, 2012) Eliiyi Türsel, Deniz; Nasibov, Efendi; Ozkilcik, Mefharet; Kuvvetli, Umit
In this study, we handle a real life optimization problem of a metropolitan city bus service. The problem's focus is the fuel consumption due to dead mileage, given the bus requirements of all route schedules. We obtain the optimal route bus-garage allocations that minimize the total distance covered in all pull-out and pull-in trips, and reach significant improvement levels with respect to the current situation. We consider the midday demand fluctuations on each route, so that some of the buses have to make extra pull-in and pull-out trips before parking at their night garages after ending their last service trips. Moreover, we develop a multicriteria model which takes into account the fuzzy levels of passenger satisfaction and parking safety combined with the previous minimization objective. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Program Committee