Scheduled Stops (Input Form 8D)

A scheduled stop is a location on a route where the trains operating on that route come to a stop.

They remain stopped for a period of time which is known as the dwell time. During this time, the number of persons aboard the train is changed by the number of persons entering or leaving the train. After the dwell time has elapsed, the train begins to accelerate and travel along its route.

The user must specify the number of scheduled stops for each route which is being simulated.

For each stop, the user must specify the location of the front of the train when it comes to a stop, the dwell time, and the number of persons entering the train at the stop. The location of the stop does not

necessarily have to be at a station, although it probably will be located at stations in the system. Stops may also be located in portions of the route that are outside the tunnel system.

The SES train performance subprogram also keeps track of the number of passengers onboard the train. Changes in the number of passengers aboard the train affect the train mass which changes the acceleration profile and other performance characteristics of the vehicle. The user must specify the number of persons aboard the train at the scheduling origin, and for each stop the number of persons entering the train must be specified. The number of persons entering the train at a stop is the net change in passengers at the stop. A positive number indicates more passengers are entering than leaving the train, and a negative number indicates more passengers are exiting than entering the train.

The train weight consists of two parts: the empty car weight (Input Form 9E) and the weight of the passengers (average patron weight on Input Form 1G).

* The total number of user-defined and program-created track sections is given by the following equation:

TNITS = NTS + NLSB + 2 x NSTOPS where: TNITS = Total Number of Internal Track Sections for a Route

NTS = Number of Track Sections which are defined by user NLSB = Number of Line Segment Boundaries

- Equal to the number of line segments that the route passes through plus one.

7-15 The train may be simulated in two different ways. First, the user may enter the average empty car weight, the number of persons aboard train at scheduling origin and the number of persons entering the train at each stop. Second, if the number of persons entering the train is not available, then the average number of persons aboard train at scheduling origin may be entered. This number can be kept constant for the remainder of the simulation by entering a zero for the number of persons entering the train at each stop.

User Suggestions. Should the user desire to simulate stalled trains within the tunnel system, this may be done in either of two ways; the first may be used to examine the steady-state flow conditions produced by ventilation fans, and the second method would more accurately examine the transition from normal operation to the steady-state condition.

Steady-state ventilation may be examined by using a stop of long dwell time to position a stalled train in the proper location. The user would enter the train data and the train routes in a manner similar to that for the simulation of normal train operation. If train performance Option 1 (implicit train performance) is used, the user would initialize the system with one train in operation. This train should be located in the position of the stalled train, with a speed of zero, and a long remaining dwell time. The user is required to specify to the program the number of trains in operation at initialization. For each train which is in

operation, at initialization the user must specify the train location along its route, train speed, route number, train type, acceleration grid temperature, and deceleration grid temperature and, if the train is stopped, the remaining dwell time. All of the above information can be taken directly from a print (either detailed or abbreviated) of the instantaneous status of the system, except the remaining dwell time, which can be estimated by determining when the train came to a stop from prints of the system status at times prior to the time for which the trains are being initialized. The train would then be placed into operation at that location, and remain there for the duration of the dwell time, which should be longer than the

maximum simulation time. The user should also enter a large value for the delay time before dispatching the first train on all the routes to prevent interference from other trains which would normally be dispatched into the system on their respective routes. Fans can be switched on at the beginning of the simulation and after an initial run-up period, the resulting steady-state airflow rates and air velocities can be observed throughout the system.

A more detailed study of a train breakdown can be performed by observing the transition from normal train operation to fan ventilated operation. This can be done by defining a system with the train data and train route information as would be done for normal operation. In addition, another route would be defined which is similar to the existing route except that it has only one train dispatched on it and has a scheduled stop of long dwell time at the point where the stalled train is to be located.

The system would be simulated in the normal mode of train operation until it had reached stabilization. Then train operation on the normal route would be suspended and, after one headway had elapsed, the train would be dispatched onto the route that contains the extra stop which is being used to simulate the train breakdown point. After this train has come to a halt, the user can switch on the emergency ventilation fan. The results of such a simulation would show the die-down of the stabilized

airflow rates, and the length of time after the fans are switched on that they become effective and

establish the minimum required airflows (see SEDH Vol. I, Part 3). The designer must not only specify that sufficient airflow is produced in the area of a stalled train, but this airflow must be established in a

reasonable time after the fans are switched on. The designer might also wish to investigate the effects of train operation on opposing routes or the effects of other stalled trains within the system upon the emergency ventilation airflow rates.