Variable Speed Signs

One of the trigger objects that may be specified within an additional-file allows the simulation of variable speed signs. The syntax for such an object is given in the following

# Definition in a single file

    <additional>>
        <variableSpeedSign id="vss0" lanes="middle_0">
            <step time="0" speed="2.8"/>
            <step time="100" speed="47.22"/>
            <step time="200" speed="-1"/>
        </variableSpeedSign>
    </additional>

The following attributes are used within the `VariableSpeedSign` element:

Attribute Name | Value Type | Description
--- | --- | ---
id | id (string) | The id of the Variable Speed Signal element (user choice)
lanes | ids (string list) | The ids of the lanes of the simulation network that shall be affected
file | string | optional file in which the time and speed values are defined

Each `step`-element is a combination of the time the next new speed shall be set and the speed to set itself and uses the following attributes:

Attribute Name | Value Type | Description
--- | --- | ---
time | time (int) | Time in which the speed will be changed
speed | speed (double) | New speed (if no value or a negative value is given, the speed will be reset to the original network value)

# Definition with an external file

Instead of defining the speed changes of a `<variableSpeedSign>` in the same file, it may also be read from a second file as follows:

    <additional>
      <variableSpeedSign id="VSS_ID" lanes="LANE_IDS" file="DEF_FILE">
         <step time="<TIME>" speed="<SPEED>"/>

         ... further entries ...

      </variableSpeedSign>
    </additional>

A file name can be supplied, called <DEF_FILE> within the schema above. This file must contain the information about when a certain speed shall be set onto the lane. This file has the following format:

    <vss>
      <step time="<TIME>" speed="<SPEED>"/>
      <step time="<TIME>" speed="<SPEED>"/>

      ... further entries ...

    </vss>

Examples for `variableSpeedSign` definitions can be obtained from our test suites

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