Problem Description
DocName Project Version FullName ShortDescription
 ProblemDescription  RailwayCrossing  V1    
The SDL and MSC (SAM) workshop provides an open discussion arena in the year between SDL Forums, which are held every two years. Part of the 3rd SAM Workshop is an SDL-2000 design contest.

The task is to specify a railway crossing with the following characteristics:

  1. There are a number of tracks for the trains. The specification should be generic in the number of tracks.

  2. There is a controller, taking into account the number of cars waiting and the trains approaching.

  3. There is a gate for cars, which must be controlled. The pattern of cars approaching is simply given by a constant delay between the cars.

  4. Each track has two sensors: one sensor when a train is approaching and one sensor when the train is leaving the gate. There is a sensor that indicates when there is more than one car waiting.

  5. There is a signal on each track informing the trains if they are allowed to pass or if they have to stop.

  6. The controller can act either by closing the gate or by stopping a train (setting a closing signal). Each of these actions has to be finished before the train reaches the gate.

  7. Trains: The solution should be generic in the number of trains. A train will start the breaking phase as soon it sees a stopping signal and restart when the stopping signal goes off. All trains on the same track are supposed to run in the same direction and with a minimal delay between them depending on their speed (a train must be able to stop even if the preceding one stops immediately). There are regular trains, which have a small (maximal) speed and fast trains, which can run faster. Regular and fast trains never run on the same track.

  8. The active elements of the system are the trains, the sensors, the controller and the gate. The cars are not considered to be in the system.

  9. The solution should allow several strategies of the gate controller to be checked.

  10. At least the following strategies should be possible: trains take precedence - at least those with high speed; cars take precedence if there are too many waiting cars. Furthermore, each spec should also provide a strategy.

  11. There will be a (small) change in the requirements published in the first week of April 2002. Participants are expected to show how they were able to adjust their specification to this change.

The winner of the contest will be the specification(s) that best demonstrate(s) the use of SDL and/or MSC.

Name ModelName Description