Traffic lights

  • This is of course about light signalling systems (LZA) (or light signal systems/LSA, as our southern neighbours call them) and their signal heads, but who uses these terms? OK, here in the forum there are probably many... ;-)

    1 Definitions of terms

    In the following article and in the MapEditor the following terms are mostly used:

    • Traffic light system: The "central" running in the background with its processing logic. Typically, there is one traffic light per intersection, but it can also control several, possibly contiguous intersections. A traffic light system has (currently!) exactly one turnaround time, i.e. as soon as traffic lights are to switch independently of each other, they must be divided into separate traffic lights. Conversely, if certain traffic lights are to work independently of each other, they must (currently still) be configured in a common traffic light system.
    • Traffic light: Officially it is called "signal generator": The thing on the mast, which usually has three traffic light optics - for red, yellow and green. ;-)
    • Traffic light optic: A single "lamp", which for example can only show "red".
    • Direction: A logical driving direction. All traffic lights that belong to this direction always show the same. On a simple intersection, the lanes of a street that meet each other may well be assigned to the same "direction", since they switch completely the same way. On more complex intersections, however, it often happens that oncoming traffic gets red or green at a different time. In this case, separate "directions" must be defined for this. The same applies to left and right turning traffic lights.

    2 Create and edit new traffic lights

    To create a new traffic light system, click on "Street" on the left and click on the "+" below the (initially empty) list of traffic lights. After entering an easily understandable name, a new entry appears in the list.

    To edit the properties of a new or existing traffic light, simply double-click on the entry for the traffic light to be edited.

    3 Configure traffic lights

    3.1 The dialog box


    At the top, the round trip time should be set first. If this is not yet known exactly, it is advisable to use a value that is too high. Below this is the area in which the individual directions are displayed, each line represents one direction. At the front of each line is the name of the direction (this should also be easy to understand, as it is needed later to configure the traffic lights and paths), next to it is the representation of the individual phases, which are suitably coloured and labelled with the ID of their term in the upper left-hand corner.

    Below the lowest direction, the requests follow, whereby each request also has its own line with name.

    At the bottom are the buttons for adding and deleting directions (whereby this is only possible with the lowest direction) and for creating new requests. Requests can be deleted by clicking on the "-" at the end of each line.

    3.2 Edit phases

    Phases can be added by clicking on the "+" at the back of the respective line in the desired direction. By clicking on the phase, its properties can be set:

    At the top you can first set the length of the phase, below which term should be shown. Here it is important to know that for a "common" term, e.g. "red", three terms with different IDs are provided. In this way, it is possible to introduce additional phases in which it is still necessary to stop, but in which the traffic light shows not just "red", but possibly additional or different information.

    The following terms are available:

    • 0 to 2: red
    • 3 to 5: Red-yellow, i.e. the phase that comes after red and before green
    • 6 to 8: Green, where 7 is unofficially used for green flashing light where cars are allowed to continue driving
    • 9 and 10: yellow, i.e. the phase that comes after green and before red, 10 is unofficial for a green flashing light at which the cars should stop
    • 11: Green-yellow, a phase that appeared in the GDR after green and before yellow
    • 12: traffic light switched off, direction of priority (no flashing light)
    • 13: traffic light switched off, from secondary direction (yellow flashing light)
    • 14-16: User defined

    3.3 Process requests

    To process requests, simply click on the white area to the right of the request name.

    The setting shown means: As soon as the traffic light has reached the "9.9s" position, the system checks whether the corresponding request has been activated (button pressed, driven via induction loop, IBIS registration, etc.). In this case the check mark "...if no request is present" is set, i.e. the action takes place exactly when no request is present. The action can be either "wait" or "jump". Here "jump" is activated and a corresponding position is preselected.

    So: If the traffic light reaches the position 9.9s, the system jumps to 20s if there is no request. In the shown case (traffic light Buchenstr. on the diorama map) the traffic light phase is skipped, where the tram coming from Sperberstr. drives to the yard, if there is no need (request).

    There is another requirement at Buchenstr:

    Since there is neither cross traffic nor pedestrian traffic lights, the traffic light phase only has to "work" if there is also a request from the tram. Therefore, there is a "stop" at the point where the tram traffic is green, i.e. the hook "Jump" is not set.

    This means that the system always stops there and only continues to run when a tram requests somewhere.

    Important: The request system does not cover all cases by far, i.e. changes may occur in the course of the further development of LOTUS!

    4 Link traffic lights, tracks and streets with traffic light systems

    If the traffic light system has been defined, the streets, tracks and normal traffic light optics can now be linked:

    • Select the desired traffic light on the left
    • As desired, any number of paths and (normal) traffic lights can be marked (multiple and mixed is also possible), but only those of a common direction
    • Left to "Mark. Obj. to be added to the plant".
    • Select the desired crossing direction

    By the way, conversely, all streets and tracks that belong to a certain direction of a certain traffic light system can also be marked: Simply select the traffic lights, click on "Mark obj./paths with system" and select the desired crossing direction.

    5 Linking request traffic lights and request boxes with traffic lights

    Here the procedure is very similar:

    • Select the desired traffic light on the left
    • As desired, any number of request boxes and request traffic light optics can be marked (multiple and mixed is also possible), but only for a common request
    • Click on "Add request object" on the left.
    • Select the desired request