The conceptual
background
The track system
The operating principle
The interbus system
The control program
Some photographs
The model train system
The basic operating principle
The basic idea of running trains on the track system is the following: each of the up to eight trains that can currently be operated simultaneously by convention starts from one of the sidings OC_ST_2/3, IC_ST_2/3 and KH_ST_1/2/3/4 of the switchyards and eventually has to return to its start position. The route along which each train is about to travel in between is given by a schedule, specified as a sequence of switchyards through which the train has to pass. The selection of the sidings in each switchyard, other than that of the final destination to which the train must return, is left to arbitration. Thus, a typical schedule as it may be specified by the operator of the system may have the form
where O,I and K stand for the switchyards of the outer and inner main tracks and for the pass track, respectively. Executing this schedule for a train, say, in start position IC_ST_2 would move the train one lap through the inner main track IC, then switch tracks to move it to the switchyard of the outer main track OC, complete a lap in OC, then move it on to the KH switchyard of the pass track where the train is oriented clockwise, have it go twice around the pass track, then have it leave the KH switchyard toward the OC switchyard, from there have it switch tracks again to go next to the switchyard IC of the inner main track, and finally have it complete to more laps on the inner main track before it returns to the initial position IC_ST_2.
A complete session is defined by similar, freely chosen schedules for all trains, of which some may be trivially empty, meaning that the trains are not moving. These schedules are under the control of a computer program executed concurrently according to the rules of the game. To this end, each of the schedules is expanded by the sequence of track sections which a train must pass through when moving from one switchyard to the next, e.g., through the sections OC_ST_4, OC_LN_0, OCIC_LN_0, OCIC_LN_1, OCIC_LN_2, IC_LN_5, IC_ST_0 when going from OC_ST_1/2/3 to IC_ST_1/2/3, specified as ...OI... in the schedule. When moving through one of the sections, the control program has to decide whether and when permission for passage through the next section in sequence may be granted, depending on other trains that may occupy this section or compete for its allocation. A session is complete after all trains have arrived at their initial positions.
The trains do not carry identifications with them. They are merely identified by their unique starting positions and by following up on the parts of the schedules which they have completed in some actual distribution of trains over the tracks. To determine actual train positions, there are little magnets attached to the front and backends of the trains which, upon crossing, close little reed contacts positioned at both ends of each track section. The signals received from the reed contacts are by the control program related to the trains that have triggered them.
22.07.2003