An Algorithm for Train Movement Simulation. Marcelo Moretti Fioroni Rui Carlos Botter

Transcription

1 An Algorithm for Train Movement Simulation Marcelo Moretti Fioroni Rui Carlos Botter

2 Discrete Event Simulation Branch of Operational Research: study of complex systems using models. Biggest challenge when building a model: the human decision representation: Humans has the ability to handle new situations, but computers not (nor simulation models); The model must be prepared to handle every situation that happens at the system representation; Required to model some systems, even with simplifications;

3 Railroad Simulation Important to support decisions about line expansions, new stations and locomotive / wagons fleet; Simulation of large rail networks: Interaction of many kinds of trains over many kinds of line tracks and stations; The decision for train movement over the network is difficult like the real system; The real system problems, like train deadlocks or collisions, can happen at the model, and must be avoided with some kind of intelligence;

4 Railroad Simulation Real railroad networks requires a centralized operational control to organize the train flow. Simulation Models requires an algorithm that can avoid the main conflicts.

5 Train Movement Algorithm Supported structures at the rail line (most common in Americas): Single and double line; Non-signalized line (line sections where the train cannot stop for traffic reasons); Signalized line, where the train can stop at section breaks that are segments of bigger lines where the train can stop for traffic reasons; All lines bidirectional; Special activity lines at the yards. Lines where the train can stop for some time, to load, unload or do maintenance; Crossig yard lengh;

6 Train Movement Algorithm Step 1: Find the next yard where the train can stop. Step 2: Check if the path is free to that position: Every line between this present position and the position identified at step 1 are reserved for the same direction of this train or is free; If the train will do some activity at the next yard, check if the corresponding line is free; The next line or section is free; If the line is single, The sum of trains moving from the opposite direction between the next station (inclusive) and the second station, is equal or less than the capacity of the next station, to avoid deadlocks.

7 Train Movement Algorithm Step 3: Reserve the path, blocking the yards or reserving the lines to the direction that will be used by this train; Step 4: Choose the movement time and move to the next line or section or yard: Step 5: Release the line / section /yard it just left. Return to step 4, until the train arrives at the position identified at step 1; Step 6: Do the activity at this yard (if necessary). Return to step 1 and continue the movement until the destination station is reached;

8 Algorithm Demonstration For each rail line between crossing yards, the model must keep information about: Actual line flow direction; Actual number of trains moving for each direction; Number of tracks (double or single); Actual status of each blockage section if it is a signalized line, or the status of the entire line if it is not signalized. Experimental line:

9 Algorithm Demonstration Conflict case 1: Two trains moving from opposite directions

10 Algorithm Demonstration Conflict case 2: Two trains moving to the same direction, and one train moving to opposite direction

11 Algorithm Demonstration Conflict case 3: Two trains moving to the same direction, and two trains moving to opposite direction

12 Conclusions The algorithm can handle train movement conflicts on a detailed representation of the line; Some situations cannot be handled, like a faster train trepassing an slower train; The proposed algorithm can be improved to handle more situations in the future.

13 Implementation Example of this algorithm partially implemented on a simulation model built on the Arena simulation package;

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