Nikola Obrenovic

Journal publications [4]

2024

Obrenovic N., Atac S., Bierlaire M. (2024). Light electric vehicle sharing systems: Functional design of a comprehensive decision making solution. Transportation Research Part A: Policy and Practice 182 (104043)

The functional design of a decision support system for a state-of-the-art vehicle sharing system (VSS) inevitably includes the selection or definition of methodologies for planning and managing the observed VSS. In this paper, our focus is on an innovative VSS that utilizes light electric vehicles. Our goal is to specify the functions of a comprehensive decision making solution for such a VSS through a qualitative and systematic literature and system analysis. To achieve this goal, we rely on the holistic VSS management framework developed in our previous research. As a result of our study, we identify possible solution methodologies or algorithms for implementing functions of the designed decision making solution, and propose the necessary adjustments for their application in the case of light electric vehicles, or note any research gap. With these findings, we provide justified guidance to practitioners in creating these solutions, with the aim of reducing development time.
```
@Article{ObreAtacBier24,
  author = {Nikola Obrenovic and Selin Atac and Michel Bierlaire},
  title = {Light electric vehicle sharing systems: Functional design of a comprehensive decision making solution},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2024},
  volume = {182},
  number = {104043},
  DOI = {10.1016/j.tra.2024.104043},
  note = {Accepted on Mar 09, 2024}}}
```

2021

Atac S., Obrenovic N., Bierlaire M. (2021). Vehicle Sharing Systems: A Review and a Holistic Management Framework. EURO Journal on Transportation and Logistics 10 (100033)

Although different vehicle sharing systems (VSSs) use different vehicle types, the management challenges and optimization problems to be solved are similar or even the same. This observation led us to create a generalized and holistic VSS management framework, which aims to be applicable to the system using any vehicle type. The framework components, their mutual relationships, and framework tasks have been identified through a thorough and systematic literature review. Furthermore, the literature is positioned in the line with the framework. Finally, the framework and systematic literature review allowed us to identify gaps in the literature, and interesting research avenues.
```
@Article{AtacObreBier21,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {Vehicle Sharing Systems: A Review and a Holistic Management Framework},
  journal = {EURO Journal on Transportation and Logistics},
  year = {2021},
  volume = {10},
  number = {100033},
  DOI = {10.1016/j.ejtl.2021.100033},
  note = {Accepted on Feb 24, 2021}}}
```

2020

Mueller F., Guerster M., Obrenovic N., Bierlaire M. (2020). Can regional railway become emission-free with recently announced vehicles? - A case study of Bavaria. European Journal of Transport and Infrastructure Research 20 (4):286-305


@Article{MuelGuerObreBier20,
  author = {Florian Mueller and Markus Guerster and Nikola Obrenovic and Michel Bierlaire},
  title = {Can regional railway become emission-free with recently announced vehicles? - A case study of Bavaria},
  journal = {European Journal of Transport and Infrastructure Research},
  year = {2020},
  volume = {20},
  number = {4},
  pages = {286-305},
  DOI = {10.18757/ejtir.2020.20.4.5439},
  note = {Accepted on Sep 01, 2020}}}

2019

Obrenovic N., Lukovic I., Ristic S. (2019). Consolidation of database check constraints. Software & Systems Modeling 18 (3):2111-2135

Independent modeling of various modules of an information system (IS), and consequently database subschemas, may result in formal or semantic conflicts between the modules being modeled. Such conflicts may cause collisions between the integrated database schema of a whole IS and the modeled subschemas. In our previous work, we have proposed criteria and algorithms for identifying and resolving such conflicts so as to provide a consolidation of database subschemas with the integrated database schema with respect to various database concepts, such as domains, relation schemes, primary key constraints and referential integrity constraints. In this paper, we propose a new approach and algorithms for identifying conflicts and testing consolidation of subschemas with the integrated database schema against check constraints. The proposed approach is based on satisfiability modulo theory (SMT) solvers. Hereby, we propose the integration of SMT solvers into our MDSD tool, aimed at supporting a database schema integration process.
```
@Article{ObrLukRis2019,
  author = {Nikola Obrenovic and Ivan Lukovic and Sonja Ristic},
  title = {Consolidation of database check constraints},
  journal = {Software \& Systems Modeling},
  year = {2019},
  volume = {18},
  number = {3},
  pages = {2111-2135},
  DOI = {10.1007/s10270-017-0637-2},
  note = {Accepted on Nov 24, 2017}}}
```

Book chapters [2]

2023

Atac S., Obrenovic N., Bierlaire M. (2023) A General Framework to Evaluate Different Rebalancing Operations Strategies in One-Way Car Sharing Systems. In Grothe, O., Nickel, S., Rebennack, S., Stein, O. (ed) Operations Research Proceedings 2022. OR 2022., Springer [ISBN 978-3-031-24906-8]


@InProceedings{AtacObreBier,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {A General Framework to Evaluate Different Rebalancing Operations Strategies in One-Way Car Sharing Systems},
  year = {2023},
  booktile = {Operations Research Proceedings 2022. OR 2022.},
  editor = {Grothe and  O. and  Nickel and  S. and  Rebennack and  S. and  Stein and  O.},
  series = {Lecture Notes in Operations Research},
  publisher = {Springer}}}

Lalic M., Obrenovic N., Brdar S., Lukovic I., Bierlaire M. (2023) Assisting Passengers on Rerouted Train Service Using Vehicle Sharing System. In Cappanera, P., Lapucci, M., Schoen, F., Sciandrone, M., Tardella, F., Visintin, F. (ed) Optimization and Decision Science: Operations Research, Inclusion and Equity, Springer [ISBN 978-3-031-28862-3]


@InProceedings{LaliObreBrdaLukoBier23,
  author = {Maksim Lalic and Nikola Obrenovic and Sanja Brdar and Ivan Lukovic and Michel Bierlaire},
  title = {Assisting Passengers on Rerouted Train Service Using Vehicle Sharing System},
  year = {2023},
  booktile = {Optimization and Decision Science: Operations Research, Inclusion and Equity},
  editor = {Cappanera and  P. and  Lapucci and  M. and  Schoen and  F. and  Sciandrone and  M. and  Tardella and  F. and  Visintin and  F.},
  volume = {9},
  series = {AIRO Springer Series},
  publisher = {Springer},
  pages = {277-287}}}

Technical reports [1]

2019

Mueller F., Guerster M., Obrenovic N., Bierlaire M. (2019). Can regional railway become emission-free with recently announced vehicles? - A case study of Bavaria. Report TRANSP-OR 191028


@TechReport{MuelGuerObreBier19,
  author = {Florian Mueller and Markus Guerster and Nikola Obrenovic and Michel Bierlaire},
  title = {Can regional railway become emission-free with recently announced vehicles? - A case study of Bavaria},
  institution = {Transport and Mobility Laboratory, Ecole Polytechnique F\'ed\'erale de Lausanne},
  year = {2019},
  type = {Technical Report},
  number = {TRANSP-OR 191028},
  address = {Lausanne, Switzerland}}}

Articles in conference proceedings [9]

2022

Obrenovic N., Atac S., Bortolomiol S., Brdar S., Marko O., Crnojevic V. (2022) The crop plant scheduling problem. Proceedings of the Italian OR Days 2022 (GOR), 30 August-02 September, Florence, Italy


@InProceedings{ObrAtaBor_ItalianOR2022,
  author = {Nikola Obrenovic and Selin Atac and Stefano Bortolomiol and Sanja Brdar and Oskar Marko and Vladimir Crnojevic},
  title = {The crop plant scheduling problem},
  booktime = {Proceedings of the Italian OR Days 2022 (GOR), 30 August-02 September},
  year = {2022},
  address = {Florence, Italy}}}

Atac S., Obrenovic N., Bierlaire M. (2022) A general framework to evaluate different rebalancing operations strategies in one-way car sharing systems. Proceedings of the International Conference on Operations Research (OR 2022), 06-09 September, Karlsruhe, Germany


@InProceedings{AtaObrBie_GermanOR2022_v0,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {A general framework to evaluate different rebalancing operations strategies in one-way car sharing systems},
  booktime = {Proceedings of the  International Conference on Operations Research (OR 2022), 06-09 September},
  year = {2022},
  address = {Karlsruhe, Germany}}}

Atac S., Obrenovic N., Bierlaire M. (2022) Evaluating different strategies to solve rebalancing operations in car sharing systems. Proceedings of the 22nd Swiss Transport Research Conference (STRC), 18-20 May, Ascona, Switzerland


@InProceedings{AtaObrBie_STRC2022,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {Evaluating different strategies to solve rebalancing operations in car sharing systems},
  booktime = {Proceedings of the 22nd Swiss Transport Research Conference (STRC), 18-20 May},
  year = {2022},
  address = {Ascona, Switzerland}}}

2021

Atac S., Obrenovic N., Bierlaire M. (2021) A multi-objective approach for station clustering in bike sharing systems. Proceedings of the 21st Swiss Transport Research Conference (STRC), 12-14 September, Ascona, Switzerland


@InProceedings{AtaObrBie_STRC2021,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {A multi-objective approach for station clustering in bike sharing systems},
  booktime = {Proceedings of the 21st Swiss Transport Research Conference (STRC), 12-14 September},
  year = {2021},
  address = {Ascona, Switzerland}}}

2020

Atac S., Obrenovic N., Bierlaire M. (2020) Bike Sharing Systems: Does demand forecasting yield a better service?. Proceedings of the 9th Symposium of the European Association for Research in Transportation (hEART), 3-4 February 2021, Lyon, France


@InProceedings{AtaObrBie_hEART2020,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {Bike Sharing Systems: Does demand forecasting yield a better service?},
  booktime = {Proceedings of the 9th Symposium of the European Association for Research in Transportation (hEART), 3-4 February 2021},
  year = {2020},
  address = {Lyon, France}}}

Atac S., Obrenovic N., Bierlaire M. (2020) Vehicle sharing systems: Does demand forecasting yield a better service?. Proceedings of the 20th Swiss Transport Research Conference (STRC), 13-14 May, Ascona, Switzerland


@InProceedings{AtaObrBie_STRC2020,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {Vehicle sharing systems: Does demand forecasting yield a better service?},
  booktime = {Proceedings of the 20th Swiss Transport Research Conference (STRC), 13-14 May},
  year = {2020},
  address = {Ascona, Switzerland}}}

2019

Atac S., Obrenovic N., Bierlaire M. (2019) A holistic decision making framework for a vehicle sharing system. Proceedings of the 23rd European Conference on Advances in Databases and Information Systems (ADBIS), 08-11 September, Bled, Slovenia


@InProceedings{AtaObrBie_ADBIS2019,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {A holistic decision making framework for a vehicle sharing system},
  booktime = {Proceedings of the 23rd European Conference on Advances in Databases and Information Systems (ADBIS), 08-11 September},
  year = {2019},
  address = {Bled, Slovenia}}}

Atac S., Obrenovic N., Bierlaire M. (2019) An optimization framework for light electric vehicle sharing systems. Proceedings of the 19th Swiss Transport Research Conference (STRC), 15-17 May, Ascona, Switzerland


@InProceedings{AtaObrBie_STRC2019,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {An optimization framework for light electric vehicle sharing systems},
  booktime = {Proceedings of the 19th Swiss Transport Research Conference (STRC), 15-17 May},
  year = {2019},
  address = {Ascona, Switzerland}}}

Mueller F., Schmidt K., Guerster M., Obrenovic N., Bierlaire M. (2019) Model-based economic analysis of electrification in railway - Understanding the impact of track, operations, and uncertainties. Proceedings of the 19th Swiss Transport Research Conference (STRC 2019), May 15-17, Ascona, Switzerland


@InProceedings{Mueller_STRC2019,
  author = {Florian Mueller and Kilian Schmidt and Markus Guerster and Nikola Obrenovic and Michel Bierlaire},
  title = {Model-based economic analysis of electrification in railway - Understanding the impact of track, operations, and uncertainties},
  booktime = {Proceedings of the 19th Swiss Transport Research Conference (STRC 2019), May 15-17},
  year = {2019},
  address = {Ascona, Switzerland}}}

Talks [7]

2022

Obrenovic N., Atac S., Bortolomiol S., Brdar S., Marko O., Crnojevic V. The crop plant scheduling problem September 02, 2022. Italian OR Days 2022 (AIRO 2022), Florence, Italy.


@Misc{Obr_ItalianOR2022,
  author = {Nikola Obrenovic and Selin Atac and Stefano Bortolomiol and Sanja Brdar and Oskar Marko and Vladimir Crnojevic},
  title = {The crop plant scheduling problem},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/Obr_ItalianOR2022.pdf}},
  year = {2022},
  note = {Presented at Italian OR Days 2022 (AIRO 2022), Florence, Italy}}}

2019

Buschor O., Pacheco M., Bortolomiol S., Bierlaire M., Obrenovic N., Hellwig M. Railway Disruption Management with Viriato and Algorithm Platform September 13, 2019. nextRail19 - International Rail and Mobility Conference, ETH Zurich, Zurich, Switzerland.


@Misc{Obren_nextRail_2019,
  author = {Oliver Buschor and Meritxell Pacheco and Stefano Bortolomiol and Michel Bierlaire and Nikola Obrenovic and Matthias Hellwig},
  title = {Railway Disruption Management with Viriato and Algorithm Platform},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/Obren_nextRail_2019.pdf}},
  year = {2019},
  note = {Presented at nextRail19 - International Rail and Mobility Conference, ETH Zurich, Zurich, Switzerland}}}

Atac S., Obrenovic N., Bierlaire M. A holistic decision making framework for a vehicle sharing system September 08, 2019. Modern Approaches in Data Engineering and Information System Design Workshop 2019, University of Maribor, Bled, Slovenia.


@Misc{Atac_MADEISD2019,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {A holistic decision making framework for a vehicle sharing system},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/Atac_MADEISD2019.pdf}},
  year = {2019},
  note = {Presented at Modern Approaches in Data Engineering and Information System Design Workshop 2019, University of Maribor, Bled, Slovenia}}}

2018

Obrenovic N., Lurkin V., Bierlaire M. Network Design for SBB Cargo October 25, 2018. SBB Research Fund Meeting, SBB CFF FSS , Zurich, Switzerland.


@Misc{Obren_SBBCargo_2018,
  author = {Nikola Obrenovic and Virginie Lurkin and Michel Bierlaire},
  title = {Network Design for SBB Cargo},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/Obren_SBBCargo_2018.pdf}},
  year = {2018},
  note = {Presented at SBB Research Fund Meeting, SBB CFF FSS , Zurich, Switzerland}}}

Obrenovic N., Lurkin V., Bortolomiol S., Bierlaire M. Model of the Swiss Freight Railway Network Design Problem September 06, 2018. hEART 2018, 7th Symposium of the European Association for Research in Transportation, National Technical University of Athens, Athens, Greece.


@Misc{Obrenovic_hEART_2018,
  author = {Nikola Obrenovic and Virginie Lurkin and Stefano Bortolomiol and Michel Bierlaire},
  title = {Model of the Swiss Freight Railway Network Design Problem},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/Obrenovic_hEART_2018.pdf}},
  year = {2018},
  note = {Presented at hEART 2018, 7th Symposium of the European Association for Research in Transportation, National Technical University of Athens, Athens, Greece}}}

Obrenovic N., Lurkin V., Bierlaire M. Freight railway network design problem June 12, 2018. 16th Swiss Operations Research Days, Universität Bern, Bern, Switzerland.


@Misc{ObrenovicSwissOR18,
  author = {Nikola Obrenovic and Virginie Lurkin and Michel Bierlaire},
  title = {Freight railway network design problem},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/ObrenovicSwissOR18.pdf}},
  year = {2018},
  note = {Presented at 16th Swiss Operations Research Days, Universit\ät Bern, Bern, Switzerland}}}

Obrenovic N., Lurkin V., Bierlaire M. Capacity-Oriented Marshaling and Shunting Yards Location Problem June 05, 2018. Odysseus 2018 - 7th International Workshop on Freight Transportation and Logistics, University of Cagliari, Cagliari, Sardinia, Italy.


@Misc{ObrenovicOdysseus18,
  author = {Nikola Obrenovic and Virginie Lurkin and Michel Bierlaire},
  title = {Capacity-Oriented Marshaling and Shunting

Yards Location Problem},
  howpublished = {\url{https://transp-or.epfl.ch/documents/talks/ObrenovicOdysseus18.pdf}},
  year = {2018},
  note = {Presented at Odysseus 2018 - 7th International Workshop on Freight Transportation and Logistics, University of Cagliari, Cagliari, Sardinia, Italy}}}

Reviewing [1]

Computer Science and Information Systems (1)

Research projects [2]

2017

Network Design for SBB Cargo

This project aims at developing an algorithm for the overall design of SBB cargo�s network of bundling points. SBB Cargo operates a network of 2 marshaling yards, 65 shunting yards and about 350 of small bundling points. The operation as such is costly and the network might contain redundant bundling points. The overall interest of SBB Cargo is to minimize the operating cost of their network and to compare its performance to a better network, completely designed from scratch. The resulting framework is then planned to be used to improve the current network of SBB cargo and its future development. The main research challenge of this project is to incorporate the SBB Cargo needs into one model while taking into account the specifics of the railway network and its operation. The researchers from the Transport and Mobility Laboratory (TRANSP-OR) will develop a heuristic algorithm that gives as an output a complete network design based on the inputs (cargo demand, capacity, types and costs of different bundling points). The algorithm can be further adjusted by entering the already existing bundling points. The effectiveness of the proposed algorithm will be tested thorough comparison with existing solutions. TRANSP-OR, led by prof. Michel Bierlaire, has a track record of successful projects of solving highly complex problems arising in industrial sector. This one-year project is sponsored by SBB-CFF-FFS.
- Sep 01, 2017 - Aug 31, 2018
- Sponsor: Swiss Federal Railways (SBB)
- Principal investigator: Michel Bierlaire
- Project managers: Nikola Obrenovic, Virginie Lurkin

2016

TRANS-FORM: Smart transfers through unravelling urban form and travel flow dynamics

TRANS-FORM, a cooperation between universities, industrial partners, public authorities and private operators, will develop, implement and test a data driven decision making tool that will support smart planning, and proactive and adaptive operations. The objective of the project is to better understand transferring dynamics in multi-modal public transport systems and develop insights, strategies and methods to support decision makers in transforming public transport usage to a seamless travel experience by using smart data. The tool will integrate new concepts and methods of behavioral modelling, passenger flow forecasting and network state predictions into real-time operations. TRANS-FORM is funded under the European Commission Horizon 2020 ERA-NET program.
- Mar 03, 2016 - Mar 03, 2019
- Sponsor: The Federal Department of the Environment, Transport, Energy and Communications (DETEC)
- Principal investigator: Michel Bierlaire
- Project managers: Shadi Sharif Azadeh, Riccardo Scarinci, Yuki Oyama
- Collaborators: Nicholas Molyneaux, Nikola Obrenovic

EPFL courses [6]

Spring 2019

Decision-aid methodologies in transportation.
- Level: Master
- Section: Civil Engineering
- Lecturers: Nikola Obrenovic, Tim Hillel
- Teaching assistants: Stefano Bortolomiol, Gael Lederrey, Selin Atac
- Webpage: http://transp-or.epfl.ch/courses/decisionAid2019/index.php
Optimization and Simulation.
- Level: PhD
- Section: Doctoral program in Civil and Environmental Engineering
- Lecturers: Michel Bierlaire, Yuki Oyama, Nikola Obrenovic
- Webpage: http://transp-or.epfl.ch/courses/OptSim2019/

Fall 2018

Introduction � l'optimisation et � la recherche op�rationnelle.
- Level: Bachelor
- Sections: Mechanical Engineering, Civil Engineering, Environmental Sciences and Engineering, Electrical and Electronics Engineering
- Lecturer: Michel Bierlaire
- Teaching assistants: Nikola Obrenovic, Nour Dougui, Stefano Bortolomiol, Selin Atac, Gael Lederrey
- Webpage: http://transp-or.epfl.ch/courses/optimization2018/

Spring 2018

Decision-aid methodologies in transportation.
- Level: Master
- Section: Civil Engineering
- Lecturers: Virginie Lurkin, Nikola Obrenovic
- Teaching assistants: Stefano Bortolomiol, Gael Lederrey
- Webpage: http://transp-or.epfl.ch/courses/decisionAid2018/index.php
Optimization and Simulation.
- Level: PhD
- Section: Doctoral program in Civil and Environmental Engineering
- Lecturers: Michel Bierlaire, Yuki Oyama, Nikola Obrenovic, Riccardo Scarinci
- Teaching assistants: Gael Lederrey, Zhengchao Wang
- Webpage: http://transp-or.epfl.ch/courses/OptSim2018/

Fall 2017

Introduction � l'optimisation et � la recherche op�rationnelle.
- Level: Bachelor
- Sections: Mechanical Engineering, Civil Engineering, Environmental Sciences and Engineering, Electrical and Electronics Engineering
- Lecturer: Michel Bierlaire
- Teaching assistants: Virginie Lurkin, Gael Lederrey, Nikola Obrenovic
- Webpage: http://transp-or.epfl.ch/courses/optimization2017/

PhD supervision [1]

Selin Atac, Demand-based mobility sharing systems.

MSc theses [3]

2019

Warehouse inventory management optimization in Rolex SA, Rym Karime (Civil Engineering)
- Supervision: Nikola Obrenovic, Selin Atac, Michel Bierlaire
- External expert: Bruno Delaborde
Heuristic algorithms to find market equilibria in oligopolies, Nicolas Pradignac (Computer science)
- Supervision: Stefano Bortolomiol, Nikola Obrenovic, Michel Bierlaire
- External expert: Olivier Gallay

2018-2019

Innovative technologies for improvement of airport accessibility with the applications to Geneva Airport, Thibaut Guillaume Marie Richard (Civil Engineering)
- Supervision: Nikola Obrenovic, Selin Atac, Michel Bierlaire
- External expert: Philippe Canal, Virginie Marche

Semester projects [5]

2019

Disruption-caused railway timetable rescheduling problem and its solution, Oliver Mathias Buschor

Supervision: Nikola Obrenovic, Meritxell Pacheco, Michel Bierlaire
In railway networks, unexpected disruptions may occur for different reasons and cause delays, service denial, and, consequently, passenger inconvenience. This planned master project will tackle the railway timetable rescheduling problem from a macroscopic and mesoscopic point of view in case of unexpected disruptions. The master project will consider several remediation strategies such as canceling, delaying or rerouting the trains, or introduction of other transportation modes. The other important aspect of the planned master project is its applicability in practice. Hence, the outcome of the project will be the algorithm for timetable rescheduling which will be implemented in the commercial software suite Viriato. The main functionality of Viriato is the train timetabling and it is produced by the company SMA und Partner AG. In order to prepare the candidate for the master project, this pre-study project will include several introductory tasks related to the problem comprehension, solutions approach and algorithm implementation. Therefore, the tasks of this project will be: 1) review of the relevant literature, 2) demand data preprocessing with the purpose of matching infrastructure and demand data, and 3) obtaining the knowledge of the Viriato software and its Algorithm Platform which enables extension of Viriato with third party algorithms.

2018-2019

Dynamic optimization of self-service vehicles, Mohamed Detsouli (Civil Engineering)

Supervision: Stefano Bortolomiol, Nikola Obrenovic, Michel Bierlaire
This project is a pr�-�tude project that will prepare the student to working on the Master thesis. The proposed topic is related to the dynamic optimization of self-service vehicle fleets, with a possible focus on dynamic pricing.

Towards a techno-economic evaluation framework for regional train propulsion architectures, Florian Mueller

Supervision: Nour Dougui, Nikola Obrenovic, Michel Bierlaire
Railway can be the most environmental mode for land transport. However the sector faces cost challenges. Apart from main routes, tracks are often not electrified, requiring pollutive and operational expensive diesel propulsion systems. In contrary to road vehicles, there are no commercial large-scale applications of hybrid drivetrains. Furthermore, the dependencies of hybrid drivetrains on energy supplying infrastructure, like overhead wires or recharge points, has not been researched yet. In order to assess the potential of hybrid drivetrains holistically, the project Toolbox for Optimal Railway Propulsion Architectures (TORPA) has set up a framework to define drivetrain solutions, optimize them, and compare them among each other. Prior to this semester project, 58 drivetrain architectures have been defined. One of them was optimized toward the objectives of driving CO2 emissions and investment costs, on a specific use case. However, these bare results were inconclusive and expensive to compute for more than one use case. In this semester project, we downselect the number of possible architectures, outlining the currently most relevant ones. Furthermore, we include infrastructure requirements in the definition of architectures. The metric of investment cost is extended to display the full life cycle costs of architectures. The model of driving CO2 emissions is attempted to display all vehicle life cycle emissions, but left at the current state after qualitatively stating significant CO2 contributors not included in the calculation models. In order to assess the potential of the extended framework, it was required to state test cases, define tangible experiments, and prioritize them. Previously, it is researched which parameters should be chosen to be relevant for such experiments. Thereby, representative generic test tracks are conceived. We choose the question of viability of track electrification as first test case for the software framework. Thus, the currently operating vehicle architectures for diesel or full electric operation are applied. Especially the impacts of currently existing electrification infrastructure and track parameters, like distance and stop frequency, are investigated. Firstly, we imply a track with average constitution and operation. It is found, that the break even of track electrification is reached when a third of it is already electrified due to e. g. intersection with other tracks. Furthermore, we find that stop frequency is decisive for electrification break even: Tracks with shortened stop distance may be cheaper to be operated electrically, even if there is no catenary infrastructure built up yet.

2018

A solution approach for the Multicommodity Flow Problem within rail freight transportation, Nicolas Pradignac (Computer science)

Supervision: Stefano Bortolomiol, Nikola Obrenovic, Michel Bierlaire
This project aims at studying the Multicommodity Flow Problem (MFP), which has several real life applications, particularly within the transportation sector. The project has been inspired by an ongoing research project conducted by TRANSP-OR in collaboration with SBB Cargo. In the context of railway freight operations, companies have limited availability of both railway lines and trains. Therefore, they have the goal to optimize as much as possible the usage of their resources in order to minimize the cost of transporting the goods. Such optimization problem can be modelled as a MFP. This project is composed of two stages. First, the student will learn the mathematical model of the MFP, in its two variants: node-arc formulation and path-based formulation. The two variants will be coded and tested on small instances by using a Mixed-Integer Linear Programming (MILP) solver such as CPLEX. Further, the student will implement a solution method to solve larger instances of the problem, by using either an exact method (such as column generation) or a heuristic method.

Development of a heuristic algorithm for a hub location problem, Thibaut Guillaume Marie Richard

Supervision: Nikola Obrenovic, Nicholas Molyneaux, Michel Bierlaire
In railway networks, the location of marshalling and shunting yards, i.e. facilities used for sorting and consolidation of transported goods, determines the costs of cargo transport to a great extent. Hence, each railway company is highly motivated to determine the optimal location of these yards. Such task can be represented as a multi-level facility location problem or a hub location problem. The aim of this project is the development of an heuristic algorithm for solving a facility location problem with facilities split in multiple hierarchical layers. The project will be a part of a larger research project done in the cooperation with SBB. The student will start from understanding the exact mathematical model of the mentioned problem and encode it into a heuristic algorithm, e.g. a local search algorithm or VNS. Also, the student will have to solve the problem on a smaller data set using an exact method and compare the solution with the results of the heuristic algorithm. The student needs to have good programming skills (Java or some other OO language) and knowledge of mixed integer linear programming and heuristics.