Allocation of Railway Rolling Stock for Passenger Trains

For a commercially operating railway company, providing a high level of service for the passengers is of utmost importance. The latter requires a high punctuality of the trains and an adequate rolling stock capacity. Unfortunately, the latter is currently (2002) one of the bottlenecks in the service provision by the main Dutch railway operator NS Reizigers. Especially during the morning rush hours, many passengers cannot be transported according to the usual service standards due to a shortage of the rolling stock capacity. On the other hand, a more effective allocation of the available rolling stock capacity seems to be feasible, since there are also several trains with some slack capacity. The effectiveness of the rolling stock capacity is determined mainly by the allocation of the train types and subtypes to the lines. Therefore, we describe in this paper a model that can be used to find an optimal allocation of train types and subtypes to train series. This optimal allocation is more effective than the manually planned one, which is accomplished by minimizing the shortages of capacity during the rush hours. The model is implemented in the modeling language OPL Studio 3.1, solved by CPLEX 7.0, and tested on several scenarios based on the 2001-2002 timetable of NS Reizigers. The results of the model were received positively, both by the planners and by the management in practice, since these results showed that a significant service improvement over the manually planned allocation can be achieved within a shorter throughput time of the involved part of the planning process.operations research;transportation;railways;capacity allocation;rolling stock

Fork naar Farm. deelrapport: experimentele kweek van yellowtail kingfish (Seriola lalandi) en de implementatie hiervan

In Nederland is sprake van een toenemende vraag naar duurzaam en lokaal geproduceerde vis. Het doel van het Fork naar Farm project was het begeleiden van de productie van een nieuwe vissoort binnen de Nederlandse viskweeksector en Afrikaanse meerval volgens een certificeringsschema waarin duurzaamheid een rol speelt. Binnen het kader van het Fork naar Farm project behandelt dit rapport het onderzoek naar de opkweek van de yellowtail kingfish (Seriola lalandi) in recirculatiesystemen en de implementatie hiervan in de praktijk. Er zijn verschillende groepen jonge yellowtail kingfish met een gewicht van ongeveer 0,5 gram aangekocht vanuit Australië en in Nederland opgekweekt in recirculatiesystemen. Er is in de faciliteiten van IMARES Wageningen UR onderzoek verricht naar diverse houderijomstandigheden: temperatuur, pH en saliniteit van het water en het voer

Circularization of the HIV-1 RNA genome

Genomic RNA circularization has been proposed for several RNA viruses. In this study, we examined if the 5′ and 3′ ends of the 9-kb HIV-1 RNA genome can interact. In vitro assays demonstrated a specific interaction between transcripts encompassing the 5′ and 3′ terminal 1 kb, suggesting that the HIV-1 RNA genome can circularize. Truncation of the transcripts indicated that the 5′–3′ interaction is formed by 600–700 nt in the gag open reading frame and the terminal 123 nt of the genomic RNA. Detailed RNA structure probing indicates that sequences flanking the 3′ TAR hairpin interact with complementary sequences in the gag gene. Phylogenetic analysis indicates that all HIV-1 subtypes can form the 5′/3′ interaction despite considerable sequence divergence, suggesting an important role of RNA circularization in the HIV-1 replication cycle

Allocation of Railway Rolling Stock for Passenger Trains

For a commercially operating railway company, providing a high level of service for the passengers is of utmost importance.The latter requires a high punctuality of the trains and an adequate rolling stock capacity.Unfortunately, the latter is currently (2002) one of the bottlenecks in the service provision by the main Dutch railway operator NS Reizigers.Especially during the morning rush hours, many passengers cannot be transported according to the usual service standards due to a shortage of the rolling stock capacity.On the other hand, a more effective allocation of the available rolling stock capacity seems to be feasible, since there are also a few trains with some slack capacity.The effectiveness of the rolling stock capacity is determined mainly by the allocation of the train types and subtypes to the lines.Therefore, we describe in this paper a model that can be used to find an optimal allocation of train types and subtypes to train series.This optimal allocation is more effective than the manually planned one, which is accomplished by minimizing the shortages of capacity during the rush hours.The model is implemented in the modeling language OPL Studio 3.1, solved by CPLEX 7.0, and tested on several scenarios based on the 2001-2002 timetable of NS Reizigers.The results of the model were received positively, both by the planners and by the management in practice, since these results showed that a significant service improvement over the manually planned allocation can be achieved within a shorter throughput time of the involved part of the planning process

The new Dutch timetable: The OR revolution

In December 2006, Netherlands Railways introduced a completely new timetable. Its objective was to facilitate the growth of passenger and freight transport on a highly utilized railway network, and improve the robustness of the timetable resulting in less train delays in the operation. Further adjusting the existing timetable constructed in 1970 was not option anymore, because further growth would then require significant investments in the rail infrastructure. Constructing a railway timetable from scratch for about 5,500 daily trains was a complex problem. To support this process, we generated several timetables using sophisticated operations research techniques, and finally selected and implemented one of these timetables. Furthermore, because rolling-stock and crew costs are principal components of the cost of a passenger railway operator, we used innovative operations research tools to devise efficient schedules for these two resources. The new resource schedules and the increased number of passengers resulted in an additional annual profit of 40 million euros ($60 million) of which about 10 million euros were created by additional revenues. We expect this to increase to 70 million euros ($105 million) annually in the coming years. However, the benefits of the new timetable for the Dutch society as a whole are much greater: more trains are transporting more passengers on the same railway infrastructure, and these trains are arriving and departing on schedule more than they ever have in the past. In addition, the rail transport system will be able to handle future transportation demand growth and thus allow cities to remain accessible. Therefore, people can switch from car transport to rail transport, which will reduce the emission of greenhouse gases.

Decision support for crew rostering at NS

This paper describes a method for solving the cyclic crew rostering problem (CCRP). This is the problem of cyclically ordering a set of duties for a number of crew members, such that several complex constraints are satisfied and such that the quality of the obtained roster is as high as possible. The described method was tested on a number of instances of NS, the largest operator of passenger trains in the Netherlands. These instances involve the generation of rosters for groups of train drivers or conductors of NS. The tests show that high quality solutions for practical instances of the CCRP can be generated in an acceptable amount of computing time. Finally, we describe an experiment where we constructed rosters in an automatic way for a group of conductors. They preferred our—generated—rosters over their own manually constructed rosters

Allocation of Railway Rolling Stock for Passenger Trains

For a commercially operating railway company, providing a high level of service for the passengers is of utmost importance. The latter requires a high punctuality of the trains and an adequate rolling stock capacity. Unfortunately, the latter is currently (2002) one of the bottlenecks in the service provision by the main Dutch railway operator NS Reizigers. Especially during the morning rush hours, many passengers cannot be transported according to the usual service standards due to a shortage of the ro

Reinventing Crew Scheduling at Netherlands Railways

In this paper we describe the successful application of a sophisticated Operations Research model and the corresponding solution techniques for scheduling the 6,500+ drivers and conductors of the Dutch railway operator NS Reizigers (Netherlands Railways). In 2001 the drivers and conductors were very dissatisfied with the structure of their duties, which led to nation wide strikes. However, the application of the model described in this paper led to the development of an alternative production model (‘Sharing Sweet & Sour’) that both satisfied the drivers and conductors, and at the same time supported an increment of the punctuality and efficiency of the railway services. The plans produced according to the alternative production model trimmed personnel costs by about $4.8million (or1.2$7 million per year are also achievable

Top guns may not fire:Best-shot group contests with group-specific public good prizes

We analyze a group contest in which n groups compete to win a group-specific public good prize. Group sizes can be different and any player may value the prize differently within and across groups. Players exert costly efforts simultaneously and independently. Only the highest effort (the best-shot) within each group represents the group effort that determines the winning group. We fully characterize the set of equilibria and show that in any equilibrium at most one player in each group exerts strictly positive effort. There always exists an equilibrium in which only the highest value player in each active group exerts strictly positive effort. However, perverse equilibria may exist in which the highest value players completely free-ride on others by exerting no effort. We provide conditions under which the set of equilibria can be restricted and discuss contest design implications

Hierarchic interactive path planning in virtual reality

To save time and money while designing new products, industry needs tools to design, test and validate the product using virtual prototypes. These vir- tual prototypes must enable to test the product at all Product Life-cycle Management (PLM) stages. Many operations in PLM involve human manipulation of product com- ponents in cluttered environment (product assembly, disassembly or maintenance). Virtual Reality (VR) enables real operators to perform these tests with virtual proto- types. This work introduces a novel path planning architecture allowing collaboration between a VR user and an automatic path planning system. It is based on an origi- nal environment model including semantic, topological and geometric information, and an automatic path planning process split in two phases: coarse (semantic and topological information) and fine (semantic and geometric information) planning. The collaboration between VR user and automatic path planner is made of 3 main aspects. First, the VR user is guided along a pre-computed path through a haptic device whereas he VR user can go away from the proposed path to explore possible better ways. Second the authority of automatic planning system is balanced to let the user free to explore alternatives (geometric layer). Third the intents of VR user are predicted (on topological layer) to be integrated in the re-planning process. Exper- iments are provided to illustrate the multi-layer representation of the environment, the path planning process, the control sharing and the intent prediction