kth.sePublications
Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 21) Show all publications
Högdahl, J. & Bohlin, M. (2023). A Combined Simulation-Optimization Approach for Robust Timetabling on Main Railway Lines. Transportation Science, 57(1), 52-81
Open this publication in new window or tab >>A Combined Simulation-Optimization Approach for Robust Timetabling on Main Railway Lines
2023 (English)In: Transportation Science, ISSN 0041-1655, E-ISSN 1526-5447, Vol. 57, no 1, p. 52-81Article in journal (Refereed) Published
Abstract [en]

Performance aspects such as travel time, punctuality and robustness are conflicting goals of utmost importance for railway transports. To successfully plan railway traffic, it is therefore important to strike a balance between planned travel times and expected delays. In railway operations research, a lot of attention has been given to construct models and methods to generate robust timetables—that is, timetables with the potential to withstand design errors, incorrect data, and minor everyday disturbances. Despite this, the current state-of-practice in railway planning is to construct timetables manually, possibly with support of microsimulation for robustness evaluation. This paper aims to narrow the gap between the state-of-the-art optimization-based research approaches, and the current state-of-practice to construct timetables by combining simulation and optimization. The paper proposes a combined simulation-optimization approach for double-track lines, which generalizes previous work to allow full flexibility in the order of trains by including a new and more generic model to predict delays. By utilizing delay data from simulation, the approach can make socio-economically optimal modifications of a given timetable by minimizing predicted disutility—the weighted sum of scheduled travel time and total predicted delay.  In a large simulation experiment on the heavily congested Swedish Western Main Line, it is demonstrated that compared with a real-life, manually constructed, timetable large reductions of delays as well as improvements in punctuality could be obtained to a small cost of marginally longer travel times. The cost of scheduled in-vehicle travel time and mean delay was reduced by 5% on average, representing a large improvement for a highly utilized railway line. Furthermore, a separate scaling experiment indicate that the approach can be suitable also for larger problems. 

Place, publisher, year, edition, pages
Institute for Operations Research and the Management Sciences (INFORMS), 2023
Keywords
Timetabling, Train scheduling, Delay prediction, Punctuality, Railroad
National Category
Transport Systems and Logistics
Research subject
Transport Science
Identifiers
urn:nbn:se:kth:diva-316472 (URN)10.1287/trsc.2022.1158 (DOI)000854172900001 ()2-s2.0-85150301044 (Scopus ID)
Funder
Swedish Transport Administration, TRV 2016/5090Swedish Transport Administration, TRV 2020/72690
Note

QC 20231215

Available from: 2022-08-18 Created: 2022-08-18 Last updated: 2023-12-15Bibliographically approved
Minbashi, N., Zhao, J., Dick, C. T. & Bohlin, M. (2023). Application of Simulation-assisted Machine Learning for Yard Departure Prediction. In: : . Paper presented at 10th International Conference on Railway Operations Modelling and Analysis.
Open this publication in new window or tab >>Application of Simulation-assisted Machine Learning for Yard Departure Prediction
2023 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Increasing the modal share of rail freight is an ongoing goal in Europe and North America. Yards can play an important role in realizing this target by their reliable and predictable performance. We aim at predicting yard departures by implementing a simulation-assisted machine learning model via two general and step-wise concepts for including the predictors. The former adds all predictors at once, and the latter adds them per the availability or the sub-yard. The data used for training the model is a one-year real-world operational data set from a European hump yard and multiple two-year simulation data sets from a representative hump yard in North America. To the best of our knowledge, no previous research has attempted to implement a generalizable prediction model between the European and the North American contexts. The model is developed on a decision tree algorithm based on a 10-fold cross-validation process. Comparing the model performance on three data sets: the real-world, a baseline simulation, and an ultimate randomness simulation shows that the model has a similar performance in the first two data sets with a respective R-squared of 0.90 and 0.87, which shows high capturing of the variance in the data. However, adding large randomness in the simulation decreases the R-squared to 0.70. Results for the step-wise inclusion of the predictors are different for the real-world and simulation data. For the former, adding more operational predictors does not change the model performance, whereas for the latter, adding departure yard predictors increases the R-squared substantially. The global feature importance shows that for the real-world data almost all predictors contribute to a great extent to the predictions, with maximum planned length, departure week day, and the number of arriving trains as the most contributing ones, whereas for the simulation data, the departure yard predictors provide the largest contribution.

Keywords
Yards, machine learning, simulation, delay prediction, rail freight
National Category
Transport Systems and Logistics Computer Sciences
Research subject
Transport Science; Transport Science, Transport Systems; Järnvägsgruppen - Effektiva tågsystem för godstrafik; Järnvägsgruppen - Kapacitet
Identifiers
urn:nbn:se:kth:diva-327017 (URN)
Conference
10th International Conference on Railway Operations Modelling and Analysis
Projects
FR8RAIL IIIPRATAShift2Rail
Funder
Swedish Transport Administration
Note

QC 20230517

Available from: 2023-05-17 Created: 2023-05-17 Last updated: 2023-05-17Bibliographically approved
Minbashi, N., Sipilä, H., Palmqvist, C.-W., Bohlin, M. & Kordnejad, B. (2023). Machine learning-assisted macro simulation for yard arrival prediction. Journal of Rail Transport Planning & Management, 25, Article ID 100368.
Open this publication in new window or tab >>Machine learning-assisted macro simulation for yard arrival prediction
Show others...
2023 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 25, article id 100368Article in journal (Refereed) Published
Abstract [en]

Increasing the modal share of the single wagonload transport in Europe requires improving the reliability and predictability of freight trains running between the yards. In this paper, we propose a novel machine learning-assisted macro simulation framework to increase the predictability of yard departures and arrivals. Machine learning is applied through a random forest algorithm to implement a yard departure prediction model. Our yard departure prediction approach is less complex compared to previous yard simulation approaches, and provides an accuracy level of 92% in predictions. Then, departure predictions assist a macro simulation network model (PROTON) to predict arrivals to the succeeding yards. We tested this framework using data from a stretch between two main yards in Sweden; our experiments show that the current framework performs better than the timetable and a basic machine learning arrival prediction model by R2 of 0.48 and a mean absolute error of 35 minutes. Our current results indicate that combination of approaches, including yard and network interactions, can yield competitive results for complex yard arrival time prediction tasks which can assist yard operators and infrastructure managers in yard re-planning processes and yard-network coordination respectively.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Yards, Delay prediction, Macroscopic simulation, Machine learning, Rail traffic
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-324874 (URN)10.1016/j.jrtpm.2022.100368 (DOI)000923576100001 ()2-s2.0-85145972631 (Scopus ID)
Note

QC 20231122

Available from: 2023-03-20 Created: 2023-03-20 Last updated: 2023-11-22Bibliographically approved
Högdahl, J. & Bohlin, M. (2023). Maximizing railway punctuality: A microsimulation evaluation of robust timetabling methods. In: : . Paper presented at 10th International Conference on Railway Operations Modelling and Analysis, RailBelgrade 2023, Belgrade, Serbia, April 25-28, 2023.
Open this publication in new window or tab >>Maximizing railway punctuality: A microsimulation evaluation of robust timetabling methods
2023 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Punctuality is commonly recognized as one of the most important quality indicators for passenger traffic. Despite this, surprisingly few methods for explicitly maximizing punctuality by optimizing the timetable exists in the literature. We study how late-stage adjustments during the capacity allocation can improve punctuality of the traffic. In this paper, we therefore extend a combined simulation-optimization method so it can be used to explicitly maximize the predicted punctuality of a given nonperiodic timetable on a double-track line. The method is evaluated in two microsimulation experiments in the southbound direction of the Swedish Western Main Line using Railsys. We compare the method in simulation with our previous method for minimizing total disutility, two methods from the scientific literature (light robustness, and robustness in critical points) and two naïve strategies. The methods’ effectiveness is assessed in a detailed statistical analysis considering end-station punctuality, total punctuality, and the robustness measure total disutility. Only light robustness results in timetables that in simulation performs better or equally well as the given timetable (based on the national timetable) with respect to all performance measures and evaluated scenarios. The method for maximizing punctuality performs best with respect to total punctuality.

Keywords
Timetabling, Train scheduling, Railroad, Robustness.
National Category
Transport Systems and Logistics
Research subject
Transport Science
Identifiers
urn:nbn:se:kth:diva-336545 (URN)
Conference
10th International Conference on Railway Operations Modelling and Analysis, RailBelgrade 2023, Belgrade, Serbia, April 25-28, 2023
Funder
Swedish Transport Administration, TRV 2020/72690
Note

QC 20230927

Available from: 2023-09-13 Created: 2023-09-13 Last updated: 2023-09-27Bibliographically approved
Johansson, I., Palmqvist, C.-W., Sipilä, H., Warg, J. & Bohlin, M. (2022). Microscopic and macroscopic simulation of early freight train departures. Journal of Rail Transport Planning & Management, 21, Article ID 100295.
Open this publication in new window or tab >>Microscopic and macroscopic simulation of early freight train departures
Show others...
2022 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 21, article id 100295Article in journal (Refereed) Published
Abstract [en]

In Sweden and other countries it is not an uncommon practice that freight trains depart more or less on-demand instead of strictly following a pre-planned timetable. However, the systematic effects of freight trains departing late or (in particular) early has long been a contested issue. Although some microscopic simulation tools currently have the capability to evaluate the effect of freight trains departing before schedule, it has yet not been established how macroscopic simulation tools, capable of fast simulation of nation-wide networks, can manage such tasks. This paper uses a case study on a line between two large freight yards in Sweden to investigate how the results of microscopic and macroscopic simulation, represented by two modern simulation tools, differ when it comes to this particular problem. The main findings are that both the microscopic and the macroscopic tools replicated the empirical punctuality fairly well. Furthermore, allowing early departures of freight trains increased overall freight train punctuality while the passenger train punctuality decreased slightly, as determined by both tools. The results are encouraging, but further studies are needed to determine if macroscopic simulation is on-par with microscopic simulation.

Place, publisher, year, edition, pages
Elsevier BV, 2022
Keywords
Railway, Simulation, Microscopic, Macroscopic, Freight trains, Early departures
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-310275 (URN)10.1016/j.jrtpm.2022.100295 (DOI)000761117600002 ()2-s2.0-85124169483 (Scopus ID)
Note

QC 20220328

Available from: 2022-03-28 Created: 2022-03-28 Last updated: 2024-03-18Bibliographically approved
Minbashi, N., Bohlin, M. & Kordnejad, B. (2021). Analysis of Railyard Congestion and Departure Delay Relationship: a Case Study from Swedish Railways. In: : . Paper presented at hEART 2020 : 9th Symposium of the European Association for Research in Transportation, Lyon, France.
Open this publication in new window or tab >>Analysis of Railyard Congestion and Departure Delay Relationship: a Case Study from Swedish Railways
2021 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

In this paper we propose a macroscopic model framework for departure delay prediction from railyards. The railyard is a large area comprising three sub-yards (arrival, classification, departure). In fact, timely operation at railyard is dependent on coordinated operations in these sub-yards. More importantly, punctual functioning of railyards is crucial for increasing competitiveness of rail freight services throughout the network. Despite previous models, we considered railyard congestion at the arrival yard, time availability of each wagon at the classification yard, and time availability of locomotive at the departure yard. The core part of this paper analyzes the effect of congestion at arrival yard on departure delays. Punctuality data from two Swedish railyards for a seven-year period is used. The congestion is defined as the number of arriving trains three hours before each departure. The results showed that the highest number of delayed departures occur at congestion levels of 4-10, while correlation coefficient is around zero. Analysing the whole dataset reveals that these congestion levels are common for all departures not just the delayed ones. Therefore, we conclude that as three sub-yards are interrelated, a comprehensive definition of congestion at railyard level is required. An elaborate definition of congestion can make it a proper predictor for further delay prediction models.

Keywords
Departure Delay Prediction, Congestion, Railyards, FR8HUB, Shift2Rail
National Category
Transport Systems and Logistics
Research subject
Transport Science; Transport Science, Transport Systems; Järnvägsgruppen - Effektiva tågsystem för godstrafik; Järnvägsgruppen - Kapacitet
Identifiers
urn:nbn:se:kth:diva-284668 (URN)
Conference
hEART 2020 : 9th Symposium of the European Association for Research in Transportation, Lyon, France
Projects
Shift2RailFR8HUB
Funder
Swedish Transport Administration
Note

QC 20201130

Available from: 2020-11-02 Created: 2020-11-02 Last updated: 2022-06-25Bibliographically approved
Minbashi, N., Palmqvist, C.-W., Bohlin, M. & Kordnejad, B. (2021). Statistical Analysis of Departure Deviations from Shunting Yards: Case study from Swedish Railways. Journal of Rail Transport Planning & Management, 18
Open this publication in new window or tab >>Statistical Analysis of Departure Deviations from Shunting Yards: Case study from Swedish Railways
2021 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 18Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

Departure deviations from shunting yards impact the reliability of rail freight services and the punctuality of a railway network. Therefore, the statistical analysis of these deviations are necessary for improving the operation of trains in mixed-traffic networks. In our paper, we conduct a detailed statistical analysis of departure deviations considering individual shunting yards characteristics. We use a large freight train delay dataset comprising 250,000 departures over seven years for the two largest shunting yards in Sweden, comparable to other medium-sized shunting yards in Europe. To find the probability distribution of departure deviations, we compare four distribution functions including the exponential, the log-normal, the gamma, and the Weibull according to the maximum likelihood estimates and results of the Anderson-Darling goodness of fit test. In our experiments, we show that the log-normal distribution fits best for delayed departures across both shunting yards, and for early departures at one of them, whereas the gamma distribution fits best for early departures at the other yard. For the temporal delay distribution, we find that fluctuations in the network usage impact the percentage of delayed departures across hours and weekdays, but not across months or years. In addition, we find that freight trains are mostly delayed in the winter.  In the case of hourly delayed departures, we demonstrate that a shunting yard involved with domestic traffic showed a negative correlation between delayed departures and the network usage, whereas an international shunting yard did not, which indicates individuality in shunting yard operations impact shunting yard-network interactions. Our findings mainly contribute to better understanding of departure deviations from shunting yards, thus enhancing the operations and capacity utilization of shunting yards. Moreover, delay distributions can be beneficial in handling delays in traffic management models as well as enhancing the outputs of freight train simulation models

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Shunting yards, departure deviations, delays, the probability distribution, the temporal delay distribution, exploratory data analysis
National Category
Transport Systems and Logistics
Research subject
Transport Science; Transport Science, Transport Systems; Järnvägsgruppen - Effektiva tågsystem för godstrafik; Järnvägsgruppen - Kapacitet
Identifiers
urn:nbn:se:kth:diva-284669 (URN)10.1016/j.jrtpm.2021.100248 (DOI)000658933800003 ()2-s2.0-85103315788 (Scopus ID)
Projects
Shift2RailFR8HUBFR8RAIL III
Funder
Swedish Transport Administration
Note

QC 20210331

Available from: 2020-11-02 Created: 2020-11-02 Last updated: 2024-03-18Bibliographically approved
Minbashi, N., Bohlin, M., Palmqvist, C.-W. & Kordnejad, B. (2021). The Application of Tree-Based Algorithms on Classifying Shunting Yard Departure Status. Journal of Advanced Transportation, 2021, Article ID 3538462.
Open this publication in new window or tab >>The Application of Tree-Based Algorithms on Classifying Shunting Yard Departure Status
2021 (English)In: Journal of Advanced Transportation, ISSN 0197-6729, E-ISSN 2042-3195, Vol. 2021, article id 3538462Article in journal (Refereed) Published
Abstract [en]

Shunting yards are one of the main areas impacting the reliability of rail freight networks, and delayed departures from shunting yards can further also affect the punctuality of mixed-traffic networks. Methods for automatic detection of departures, which are likely to be delayed, can therefore contribute towards increasing the reliability and punctuality of both freight and passenger services. In this paper, we compare the performance of tree-based methods (decision trees and random forests), which have been highly successful in a wide range of generic applications, in classifying the status of (delayed, early, and on-time) departing trains from shunting yards, focusing on the delayed departures as the minority class. We use a total number of 6,243 train connections (representing over 21,000 individual wagon connections) for a one-month period from the Hallsberg yard in Sweden, which is the largest shunting yard in Scandinavia. Considering our dataset, our results show a slight difference between the application of decision trees and random forests in detecting delayed departures as the minority class. To remedy this, enhanced sampling for minority classes is applied by the synthetic minority oversampling technique (SMOTE) to improve detecting and assigning delayed departures. Applying SMOTE improved the sensitivity, precision, and F-measure of delayed departures by 20% for decision trees and by 30% for random forests. Overall, random forests show a relative better performance in detecting all three departure classes before and after applying SMOTE. Although the preliminary results presented in this paper are encouraging, future studies are needed to investigate the computational performance of tree-based algorithms using larger datasets and considering additional predictors.

Place, publisher, year, edition, pages
Hindawi Limited, 2021
National Category
Transport Systems and Logistics Computer Sciences
Identifiers
urn:nbn:se:kth:diva-303061 (URN)10.1155/2021/3538462 (DOI)000697297200001 ()2-s2.0-85115798799 (Scopus ID)
Note

QC 20211005

Available from: 2021-10-05 Created: 2021-10-05 Last updated: 2023-05-17Bibliographically approved
Minbashi, N., Bohlin, M. & Kordnejad, B. (2020). A departure delay estimation model for freight trains. In: Toni Lusikka (Ed.), Proceedings of TRA2020, the 8th Transport Research Arena 2020: Rethinking transport – towards clean and inclusive mobility: . Paper presented at the 8th Transport Research Arena 2020:, Helsinki, Finland.
Open this publication in new window or tab >>A departure delay estimation model for freight trains
2020 (English)In: Proceedings of TRA2020, the 8th Transport Research Arena 2020: Rethinking transport – towards clean and inclusive mobility / [ed] Toni Lusikka, 2020Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The main objective of this paper is to develop a macroscopic delay estimation model for freight trains departing from the marshalling yard. Freight trains are made up in large marshalling yards comprising three yards (arrival, classification, departure). On time operations in marshaling yards enhances reliability of rail freight services compared to other modes of freight transport. Currently, freight trains encounter most of their delays in marshalling yards even before entering the railway network. Therefore, it is needed to estimate the departure delay of freight trains from the marshaling yard. So far, studies have mainly focused on classification yard operations to estimate departure delay, whereas a proper delay estimation model should be able to consider processes of all three yards. We have developed our model considering main factors (yard congestion, railcar availability and locomotive availability) from all three yards. Hallsberg and Malmö Marshalling yards in Sweden were used as case study.

Series
Traficom Research Reports 7/2020, ISSN 2669-8781
Keywords
Delay Estimation; Marshalling Yards; Machine Learning; Swedish Railways; Shift2Rail
National Category
Transport Systems and Logistics
Research subject
Transport Science; Järnvägsgruppen - Effektiva tågsystem för godstrafik; Transport Science, Transport Systems; Järnvägsgruppen - Kapacitet
Identifiers
urn:nbn:se:kth:diva-284665 (URN)
Conference
the 8th Transport Research Arena 2020:, Helsinki, Finland
Projects
Shift2RailFR8HUB
Funder
Swedish Transport Administration
Note

Part of proceedings: ISBN 978-952-311-484-5

QC 20201124

Available from: 2020-11-02 Created: 2020-11-02 Last updated: 2023-05-17Bibliographically approved
Weik, N., Warg, J., Johansson, I., Bohlin, M. & Nießen, N. (2020). Extending UIC 406-based capacity analysis – New approaches for railway nodes and network effects. Journal of Rail Transport Planning & Management, 15, 100199, Article ID 100199.
Open this publication in new window or tab >>Extending UIC 406-based capacity analysis – New approaches for railway nodes and network effects
Show others...
2020 (English)In: Journal of Rail Transport Planning & Management, ISSN 2210-9706, E-ISSN 2210-9714, Vol. 15, p. 100199-, article id 100199Article in journal (Refereed) Published
Abstract [en]

Railway capacity planning aims to determine the amount of traffic that can be operated on a given infrastructure. The timetable compression method described in UIC Code 406 has become one of the standard tools in this area. Motivated by the Swedish Transportation Administration's timetable independent adaptation of the methodology and its need for extension we explore how the compression method can be applied to evaluate the capacity of the underlying infrastructure for strategic planning rather than the occupation ratio of a specific timetable. By performing ensemble averaging of scheduled train sequences we abstract from a single timetable concept and perform a distributional analysis of timetable utilization. To mitigate decomposition-induced underestimation of network effects the compression area is extended and approaches to include interdependencies between stations and lines are investigated. The methodology is applied for capacity assessment of railway stations and line segments in a case study based on the Swedish Southern Main Line rail corridor.

Place, publisher, year, edition, pages
Elsevier BV, 2020
Keywords
Capacity, Network effects, Railway stations, Simulation, Strategic planning, UIC 406 compression method, Railroads, Rails, Scheduling, Capacity analysis, Capacity assessment, Compression methods, Ensemble averaging, Railway capacity, Standard tools, Railroad transportation
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-274228 (URN)10.1016/j.jrtpm.2020.100199 (DOI)000560298800004 ()2-s2.0-85083550646 (Scopus ID)
Note

QC 20221114

Available from: 2020-07-07 Created: 2020-07-07 Last updated: 2023-03-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1597-6738

Search in DiVA

Show all publications