Scheduling seminar

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schedulingseminar@rtime.felk.cvut.cz

November 2025

1 participants
2 discussions

Hoogeveen, J.A. (Utrecht University) | November 26 | Planning shunting operations at railway hubs
by Zdenek Hanzalek 25 Nov '25

25 Nov '25

Dear scheduling researcher, We are delighted to announce the talk given by Han Hoogeveen (Utrecht University). The title is "Planning shunting operations at railway hubs". The seminar will take place on Zoom on Wednesday, November 26 at 14:00 UTC. Join Zoom Meeting https://cesnet.zoom.us/j/97711129359?pwd=8bUbSE56gVa8UilLUasEbVT8QX2HnU.1 Meeting ID: 977 1112 9359 Passcode: 599095 You can follow the seminar online or offline on our Youtube channel as well: https://www.youtube.com/channel/UCUoCNnaAfw5NAntItILFn4A The abstract follows. At night, trains are parked on shunting yards. Here cleaning and small maintenance takes place, after which the trains have to leave in the morning at the planned departure time and in the desired composition, which may require splitting and coupling during their stay at the yard. As NS (Dutch Railways) continues to expand its fleet while the available yard space remains fixed, the shunting yards are becoming increasingly congested, with occupation rates reaching up to 90%. Consequently, planning all train movements and related activities has become a complex challenge. In this talk, I will discuss the main challenges encountered in planning the shunting yards and the algorithms that we have designed to tackle these problems. First, I want to discuss the shunting problem on a single yard. We solve this problem using local search; our algorithm is the first one that is capable of solving real-world problem instances of the complete shunting and scheduling problem. Next, I want to extend the problem to the entire station area, which requires that we distribute the trains over two (or more) shunting yards, while avoiding interference with through traffic and respecting the capacity of the separate shunting yards. The main difficulty here is that the capacity of the shunting yard is not known; we use data analysis to estimate it. Finally, I want to discuss the problem of assigning shunting tasks to train drivers. This is a variant of the technician routing problem without skills, but with synchronization. We have developed an algorithm for this that is based on a novel decomposition approach. The next talk in our series will be: Laurent Houssin (ENAC, Université de Toulouse) | December 10 | Flow-shop and job-shop robust scheduling problems with budgeted uncertainty For more details, please visit https://schedulingseminar.com/ With kind regards Zdenek Hanzalek, Michael Pinedo and Guohua Wan -- Zdenek Hanzalek Industrial Informatics Department, Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, Jugoslavskych partyzanu 1580/3, 160 00 Prague 6, Czech Republic https://rtime.ciirc.cvut.cz/~hanzalek/

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[Scheduling seminar] Rachel R. Chen (UC Davis) | November 12 | Outpatient Appointment Scheduling with Waiting Time Limits
by Zdenek Hanzalek 10 Nov '25

10 Nov '25

Dear scheduling researcher, We are delighted to announce the talk given by Rachel R. Chen (UC Davis). The title is "Outpatient Appointment Scheduling with Waiting Time Limits". The seminar will take place on Zoom on Wednesday, November 12 at 14:00 UTC. Join Zoom Meeting https://cesnet.zoom.us/j/98020327183?pwd=51usye8bYlWTWomIA9ZVVqiiwmj2ec.1 Meeting ID: 980 2032 7183 Passcode: 076268 You can follow the seminar online or offline on our Youtube channel as well: https://www.youtube.com/channel/UCUoCNnaAfw5NAntItILFn4A The abstract follows. This paper studies outpatient appointment scheduling with waiting time limits, in the presence of uncertain service times, patient no-shows and unpunctual arrivals. To tackle the problem of excessively long waiting times, policymakers may impose a waiting time limit. The introduction of waiting time limits increases the complexity of model formulation by significantly increasing the number of problem scenarios. To address this challenge, we introduce the concept of virtual waiting time, representing the additional waiting time that a patient would have to incur to see the doctor beyond the imposed waiting time limit. Using this construct, we are able to unify the modeling of system dynamics of all different scenarios into one stochastic program. We develop a tailored integer L-shaped method to solve this model and test its effectiveness against two benchmarks. Specifically, the subproblem is a mixed integer nonlinear program with good properties, which allow us to deduce its optimal value without using optimization solver. We find that the presence of waiting time limits increases the job allowance between two adjacent patients, and the optimal schedule does not necessarily exhibit the well-known dome-shaped pattern. We also find that waiting time limits help reduce variation in patient waiting times across different positions in the schedule, thereby enhancing fairness in the schedule. Furthermore, our results indicate that in the presence of waiting time limits, the total cost of the system is minimized when patients tend to arrive slightly late on average. Finally, we find that when a social planner sets the limit, the clinic has incentives to misreport its true cost of serving each diverted patient, and an additional fine on top of the time limits helps improve social welfare. The next talk in our series will be: Hoogeveen, J.A. (Utrecht University) | November 26 | Planning shunting operations at railway hubs For more details, please visit https://schedulingseminar.com/ With kind regards Zdenek Hanzalek, Michael Pinedo and Guohua Wan -- Zdenek Hanzalek Industrial Informatics Department, Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, Jugoslavskych partyzanu 1580/3, 160 00 Prague 6, Czech Republic https://rtime.ciirc.cvut.cz/~hanzalek/

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