14.4 Signal reference

Signal reference means that there is some kind of link between two signals or objects. A signal reference is valid for one specific signal only.

Elements in UML model

<reference> element

In ASAM OpenDRIVE, a signal reference is represented by the <reference> element within the <signal> element.

UML class: t_road_signals_signal_reference
XML tag:   <reference> (Multiplicity: 0..*)

Signal references link a signal to another signal or object. One signal may have multiple signal references. The signal reference term should not to be confused with the <signalReference> element that is used to link a signal to multiple roads.

Table 123. Attributes of the <reference> element
Name Type Use Description

elementId

string

required

Unique ID of the linked element

elementType

e_road_signals_signal_reference_elementType

required

Type of the linked element

type

string

optional

Type of the linkage
Free text, depending on application

XML example

An example would be a traffic light which uses a <reference> to a stop line in order to specify where traffic participants have to stop on red. The stop line in turn has a <dependency> on the traffic light, since traffic should stop there only if the traffic light is red.

<signals>
    <signal s="1.0e+00"
            t="-1.0e-01"
            id="5"
            name="pedestrian_trafficlight"
            dynamic="yes"
            orientation="+"
            zOffset="3.03"
            type="1000002"
            subtype="-1"
            country="OpenDRIVE"
            countryRevision="2023"
            hOffset="0.0"
            pitch="0.0"
            roll="0.0"
            height="0.53"
            width="0.27">
        <validity fromLane="-1" toLane="-1"/>
        <reference elementId="7" elementType="signal" type="stopline"/>
    </signal>
    <signal s="1.31e+01"
            t="0.0"
            id="7"
            name="InvisibleStopLine"
            dynamic="no"
            orientation="-"
            zOffset="0.0"
            type="1100001"
            subtype="-1"
            country="OpenDRIVE"
            countryRevision="2023"
            hOffset="0.0"
            pitch="0.0"
            roll="0.0"
            height="0.03"
            width="3.75">
        <validity fromLane="-1" toLane="-1"/>
        <dependency id="5" type="pedestrian_trafficlight"/>
    </signal>
</signals>

Rules

The following rules apply to signal reference elements:

  • A signal may have multiple references.

  • The type of reference is not specifically defined in ASAM OpenDRIVE and may be set in the application.

Rules regarding the type of reference are defined in the application and are not stored in ASAM OpenDRIVE.

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