10.10 Traffic signal

The following examples use the ASAM OpenDRIVE controller element for creating signal groups that have identical signal cycles. This is in alignment with civil engineering specifications like [14].

10.10.1 X-Junction

The following example shows an X-Junction with six traffic signals for vehicles, six traffic signals for trams, and eight traffic signals for pedestrians. These are grouped into six controllers. The ASAM OpenDRIVE controller ID is used as the name of the TrafficSignalController to reference it. The trafficSignalId attributes are taken from ASAM OpenDRIVE.

Traffic signals can be modeled in two ways, just like in ASAM OpenDRIVE:

"The whole box is one traffic signal":
This results in more than one value in the observable state string in the TrafficSignalState or TrafficSignalGroupState. For example, "on;off;off" for a vehicle traffic signal or "on;off" for a pedestrian traffic signal.
"Each light bulb is one traffic signal":
This results in one value in the observable state string in the TrafficSignalState or TrafficSignalGroupState. For example, "on" or "off".

The type attribute of the ASAM OpenDRIVE signal specifies if the traffic signal was modeled as a whole box or if each light bulb was modeled individually.

Figure 49. Visual representation of the X-junction

Figure 50. Visual representation of the phases and states

<TrafficSignals>
    <TrafficSignalController name="42">
        <Phase name="stop" duration="19">
            <TrafficSignalState trafficSignalId="17251" state="on"/>
            <TrafficSignalState trafficSignalId="17252" state="off"/>
            <TrafficSignalState trafficSignalId="17253" state="off"/>
        </Phase>
        <Phase name="go" duration="12">
            <TrafficSignalState trafficSignalId="17251" state="off"/>
            <TrafficSignalState trafficSignalId="17252" state="off"/>
            <TrafficSignalState trafficSignalId="17253" state="on"/>
        </Phase>
        <Phase name="attention" duration="2">
            <TrafficSignalState trafficSignalId="17251" state="off"/>
            <TrafficSignalState trafficSignalId="17252" state="on"/>
            <TrafficSignalState trafficSignalId="17253" state="off"/>
        </Phase>
        <Phase name="stop" duration="39">
            <TrafficSignalState trafficSignalId="17251" state="on"/>
            <TrafficSignalState trafficSignalId="17252" state="off"/>
            <TrafficSignalState trafficSignalId="17253" state="off"/>
        </Phase>
    </TrafficSignalController>
    <TrafficSignalController name="43">
        <Phase name="stop" duration="19">
            <TrafficSignalState trafficSignalId="17261" state="on"/>
            <TrafficSignalState trafficSignalId="17262" state="off"/>
            <TrafficSignalState trafficSignalId="17263" state="off"/>
        </Phase>
        <Phase name="go" duration="12">
            <TrafficSignalState trafficSignalId="17261" state="off"/>
            <TrafficSignalState trafficSignalId="17262" state="off"/>
            <TrafficSignalState trafficSignalId="17263" state="on"/>
        </Phase>
        <Phase name="attention" duration="2">
            <TrafficSignalState trafficSignalId="17261" state="off"/>
            <TrafficSignalState trafficSignalId="17262" state="on"/>
            <TrafficSignalState trafficSignalId="17263" state="off"/>
        </Phase>
        <Phase name="stop" duration="39">
            <TrafficSignalState trafficSignalId="17261" state="on"/>
            <TrafficSignalState trafficSignalId="17262" state="off"/>
            <TrafficSignalState trafficSignalId="17263" state="off"/>
        </Phase>
    </TrafficSignalController>
    <TrafficSignalController name="44">
        <Phase name="go" duration="15">
            <TrafficSignalGroupState state="off;off;on"/>
        </Phase>
        <Phase name="attention" duration="3">
            <TrafficSignalGroupState state="off;on;off"/>
        </Phase>
        <Phase name="stop" duration="48">
            <TrafficSignalGroupState state="on;off;off"/>
        </Phase>
        <Phase name="stop_attention" duration="1">
            <TrafficSignalGroupState state="on;on;off"/>
        </Phase>
        <Phase name="go" duration="5">
            <TrafficSignalGroupState state="off;off;on"/>
        </Phase>
    </TrafficSignalController>
    <TrafficSignalController name="45">
        <Phase name="stop" duration="35">
            <TrafficSignalGroupState state="on;off"/>
        </Phase>
        <Phase name="go" duration="20">
            <TrafficSignalGroupState state="off;on"/>
        </Phase>
        <Phase name="stop" duration="17">
            <TrafficSignalGroupState state="on;off"/>
        </Phase>
    </TrafficSignalController>
    <TrafficSignalController name="46">
        <Phase name="stop" duration="34">
            <TrafficSignalGroupState state="on;off;off"/>
        </Phase>
        <Phase name="stop_attention" duration="1">
            <TrafficSignalGroupState state="on;on;off"/>
        </Phase>
        <Phase name="go" duration="24">
            <TrafficSignalGroupState state="off;off;on"/>
        </Phase>
        <Phase name="attention" duration="3">
            <TrafficSignalGroupState state="off;on;off"/>
        </Phase>
        <Phase name="stop" duration="10">
            <TrafficSignalGroupState state="on;off;off"/>
        </Phase>
    </TrafficSignalController>
    <TrafficSignalController name="47">
        <Phase name="go" duration="13">
            <TrafficSignalGroupState state="off;on"/>
        </Phase>
        <Phase name="stop" duration="54">
            <TrafficSignalGroupState state="on;off"/>
        </Phase>
        <Phase name="go" duration="5">
            <TrafficSignalGroupState state="off;on"/>
        </Phase>
    </TrafficSignalController>
</TrafficSignals>

10.10.2 X-Junction with broken lights

To model a broken traffic signal, the observable state of a TrafficSignalState can be used.

In this example, the original Phase instances of the TrafficSignalController with the name "45" look like this:

<TrafficSignalController name="45">
    <Phase name="stop" duration="35">
        <TrafficSignalGroupState state="on;off"/>
    </Phase>
    <Phase name="go" duration="20">
        <TrafficSignalGroupState state="off;on"/>
    </Phase>
    <Phase name="stop" duration="17">
        <TrafficSignalGroupState state="on;off"/>
    </Phase>
</TrafficSignalController>

If the traffic signal with ID "17271" had broken lights, all traffic signals would still have the same Phase instances, but show a different observable state. The TrafficSignalController with the name "45" would change to this:

<TrafficSignalController name="45">
    <Phase name="stop" duration="35">
        <TrafficSignalState trafficSignalId="17271" state="off;off"/> <!-- This light is broken-->
        <TrafficSignalState trafficSignalId="17300" state="on;off"/>
        <TrafficSignalState trafficSignalId="17360" state="on;off"/>
        <TrafficSignalState trafficSignalId="17361" state="on;off"/>
    </Phase>
    <Phase name="go" duration="20">
        <TrafficSignalState trafficSignalId="17271" state="off;off"/> <!-- This light is broken-->
        <TrafficSignalState trafficSignalId="17300" state="off;on"/>
        <TrafficSignalState trafficSignalId="17360" state="off;on"/>
        <TrafficSignalState trafficSignalId="17361" state="off;on"/>
    </Phase>
    <Phase name="stop" duration="17">
        <TrafficSignalState trafficSignalId="17271" state="off;off"/> <!-- This light is broken-->
        <TrafficSignalState trafficSignalId="17300" state="on;off"/>
        <TrafficSignalState trafficSignalId="17360" state="on;off"/>
        <TrafficSignalState trafficSignalId="17361" state="on;off"/>
    </Phase>
</TrafficSignalController>