An Interactive Train Scheduling Tool for Solving and Plotting Running Maps

Barber, Federico; Salido, Miguel Á.; Ingolotti, L.; Abril, M.; Lova, Antonio; Tormos, María Pilar

doi:10.1007/978-3-540-25945-9_64

Cited by 13 publications

(9 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This parameter represents the probability of a problem being feasible. This parameter lies in the range [0,1]. A value of τ = 0 corresponds to an overconstrained and no state is expected to be a solution ( Sol = 0).…”

Section: Constraint Ordering Heuristicmentioning

confidence: 99%

“…Numerous approaches and tools have been developed to compute railway scheduling. We summarize the application of COH into our constraintbased train scheduling tool 1 [1], which is a project in collaboration with the National Network of Spanish Railways (RENFE). We formulate train scheduling as constraint optimization problems.…”

Section: Application Of Coh To Railway Scheduling Problemmentioning

confidence: 99%

See 1 more Smart Citation

A non-binary constraint ordering heuristic for constraint satisfaction problems

Salido

2008

Applied Mathematics and Computation

Self Cite

View full text Add to dashboard Cite

Nowadays many real problems can be modelled as Constraint Satisfaction Problems (CSPs). A search algorithm for constraint programming requires an order in which variables and values should to be considered. Choosing the right order of variables and values can noticeably improve the efficiency of constraint satisfaction. Furthermore, the order in which constraints are studied can improve efficiency, particularly in problems with non-binary constraints. In this paper, we present a preprocess heuristic called Constraint Ordering Heuristic (COH) that studies the constrainedness of the scheduling problem and mainly classifies the constraints so that the tightest ones are studied first. Thus, constrainedness can be known in advance and overall inconsistencies can be found earlier and the number of constraint checks can significantly be reduced.Keywords: Heuristic Search, Constraint ordering, Non-binary Constraints, Constrainedness.1 2 IntroductionNowadays, many real problems can be efficiently modelled as Constraint Satisfaction Problems (CSPs) and solved using constraint programming techniques. Some problems can be modelled naturally using non-binary constraints [26,19,8]. Although, researchers have traditionally focused on binary constraints [24], the need to address issues regarding non-binary constraints has recently started to be widely recognized in the constraint satisfaction literature. Thus, to define heuristics to solve non-binary CSPs becomes relevant.One approach to solving CSPs is to use a depth-first backtrack search algorithm [5]. While the worst-case complexity of backtrack search is exponential, several heuristics to reduce its average-case complexity have been proposed in the literature [6]. However, determining which algorithms are superior to others remains difficult. Theoretical analysis provides worst-case guarantees which often do not reflect average performance. For instance, a backtracking-based algorithm that incorporates features such as variable ordering heuristics will often in practice have substantially better performance than a simpler algorithm without this feature [17], and yet the two share the same worst-case complexity. Similarly, one algorithm may be better than another on problems with a certain characteristic, and worse on another category of problem. Ideally, we would be able to identify this characteristic in advance and use it to guide our choice of algorithm.Many of the heuristics that improve backtracking-based algorithms are based on variable ordering and value ordering [20, 2], due to the additivity of the variables and values. However, constraints are also considered to be additive, that is, the order of imposition of constraints does not matter, all that matters is that the conjunction of constraints be satisfied [2].Thus, a real problem can be modelled as a CSP, and using some of the current ordering heuristics, it can be solved in a more efficient way by some of the backtracking-based search algorithms (Figure 1).In spite of the additivity of constraints, only...

show abstract

Section: Constraint Ordering Heuristicmentioning

confidence: 99%

Section: Application Of Coh To Railway Scheduling Problemmentioning

confidence: 99%

A non-binary constraint ordering heuristic for constraint satisfaction problems

Salido

2008

Applied Mathematics and Computation

Self Cite

View full text Add to dashboard Cite

show abstract

“…• The generation of timetables for the suburban railway network of Melbourne [2], • SAGITAIRE : a tool for the design of one day operation of the schedules, platform and route assignments of the trains for "Gare du Nord" station in Paris [3], • PRaCoSy : a project for the automation of the preparation and updating of the running map for a section of the Beijing-Guangzhou line in China [4], • CAPRES : a tool to analyse the capacity of railway networks with a saturation method [5], • The scheduling of trains on single track networks [6,7], • COMBINE2 : a European project which aim was to define a conflict resolution model to use in control centres for fixed and moving block signalling systems [8], • A generic tool for the National Network of Spanish Railways which covers many functions such as analysing the capacity, identifying bottlenecks, providing alternative planning and real-time traffic control [9]. Our first CBS formulation of the traffic management problem at junction was in [10], the last updated and detailed description of the model was in [11].…”

Section: Introductionmentioning

confidence: 99%

The contribution of state resources in a constraint-based scheduling model for conflict solving at railway junctions

Rodríguez¹

2006

WIT Transactions on the Built Environment, Vol 88

View full text Add to dashboard Cite

bstractScheduling is the process of allocating resources to activities over time. In a scheduling problem, resources are scarce and constrained in various ways (e.g. in the order of activities and the capacity of resources), and one is looking for a schedule of the activities that both satisfies the constraints and is optimal according to some criterion.Over the last decade, constraint-based scheduling (CBS) has become the dominant form of modelling and solving scheduling problems. This paper deals with a CBS model of real time management of train traffic through junctions, it focuses on the use of state resources to improve the model of conflicts between trains running in opposite directions.

show abstract

“…However, the system carried out important preprocessing heuristics [1] before executing these well-known COP solvers in order to significantly reduce the size of this type of problems.…”

Section: Discussionmentioning

confidence: 99%

“…This technique has been inserted in our system [1] and it is committed to solve this problem in order to obtain as good and feasible running map as possible. The system is able to plot the obtained running map.…”

Section: Introductionmentioning

confidence: 99%

A Topological Model Based on Railway Capacity to Manage Periodic Train Scheduling

Salido

Barber

Abril

et al.

Applications and Innovations in Intelligent Systems XII

View full text Add to dashboard Cite

Railway capacity has been a significant issue in the railway industry. Over the last few years, numerous approaches and tools have been developed to compute railway capacity. In this paper, we compute railway capacity to design a topological model for solving periodic train scheduling, developed in collaboration with the National Network of Spanish Railways (RENFE). This topological technique transforms the railway optimization problem in subproblems such that a traffic pattern is generated for each subproblem. These traffic patterns will be periodically repeated to compose the entire running map. The results show that this technique improve the results obtained by well known tools as LINGO and ILOG Concert Technology (CPLEX).

show abstract

An Interactive Train Scheduling Tool for Solving and Plotting Running Maps

Cited by 13 publications

References 3 publications

A non-binary constraint ordering heuristic for constraint satisfaction problems

A non-binary constraint ordering heuristic for constraint satisfaction problems

The contribution of state resources in a constraint-based scheduling model for conflict solving at railway junctions

A Topological Model Based on Railway Capacity to Manage Periodic Train Scheduling

Contact Info

Product

Resources

About