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:
<additional>
<variableSpeedSign id="VSS_ID" lanes="LANE_IDS" file="DEF_FILE">
<step time="<TIME>" speed="<SPEED>"/>
... further entries ...
</variableSpeedSign>
</additional>
The following attributes are used within the VariableSpeedSignal element:
| Attribute Name | Value Type | Description |
|---|---|---|
| id | id (string) | The id of the Variable Speed Signal element (user choice) |
| lanes | id (string) | The id of the lanes of the simulation network |
| file | string | optional file in which the time and speed values are defined |
Each step is a combination of the time the next new speed shall be set and the speed to set itself. 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>
The following attributes are used within the VariableSpeedSignal element:
| 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) |
A small example for usage of vss' may be found in the SUMO directory under "examples/sumo/variable_speed_signs".