IL:tvdSection

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Introduction

Documentation

Syntax

Autoexport from the XML-Schema for element IL:tvdSection of railML® version 3.2
Documentation track vacancy detection (TVD) section reports train occupancy to the interlocking
Subschema interlocking
Parents* tvdSections
Children any (0..*), assetName (0..*), belongsToOperationalPoint (0..1), designator (0..*), hasCommand (0..*), hasDemarcatingBufferstop (0..2), hasDemarcatingTraindetector (0..*), hasExitSignal (0..2), hasIndication (0..*), hasResetStrategy (0..1), hasTrackElement (0..*), hasTrainNumberField (0..*)
Attributes:
  • isBerthingTrack: True, if this section is part of a berthing track, i.e. track where trains may halt and change direction. Typically, an Interlocking assures that trains progress from section to section in an ordered sequence (aka. two/three phase release). This check would fail when a train changes direction. If this attribute is true, the interlocking doesn't carry out this check for this section. (optional; xs:boolean),

  • residualRouteCancellationDelay: The delay after which the interlocking may clear a partial route left by an unusual train run. The timer starts running when the interlocking accepts the signal man request to clear the section (DE: Restfahrstrasse auflösen) or when the interlocking algorithm detects that the train has set back (automatic route release). (obligatory; xs:duration),

  • partialRouteReleaseDelay: Delay time after which the section may be released for use in a new route (obligatory; xs:duration),

  • technology: The technology used for the TVD section to detect the presence or absence of rail vehicles. (optional; xs:string; patterns: other:\w{2,})
Possible values:
  • trackCircuit
  • axleCounter,

  • frequency: The frequency in Hertz used for the TVD section in case of a track circuit. Shall be zero for direct current. (optional; xs:decimal; minInclusive: 0; fractionDigits: 3),

  • elementNumber: element number for internal referencing in the engineering data (optional; xs:nonNegativeInteger),

  • id: unique identifier (optional; xs:string; patterns: (urn:uuid:)?[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}|\{[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\})
*Notice:
Elements may have different parent elements. As a consequence they may be used in different contexts.
Please, consider this as well as a user of this wiki as when developing this documentation further.
Aspects that are only relevant with respect to one of several parents should be explained exclusively in the documentation of the respective parent element.

Autoexport from the XML-Schema for element IL:tvdSection of railML® version 3.1
Documentation track vacancy detection (TVD) section reports train occupancy to the interlocking
Subschema interlocking
Parents* tvdSections
Children any (0..*), designator (0..1), hasDemarcatingBufferstop (0..2), hasDemarcatingTraindetector (0..*), hasExitSignal (0..2), hasResetStrategy (0..1)
Attributes:
  • isBerthingTrack: True if this section is part of a berthing track, i.e. track where trains may halt and change direction. Typically, an Interlocking assures that trains progress from section to section in an ordered sequence (aka. two/three phase release). This check would fail when a train changes direction. If this attribute is true, the interlocking doesn't carry out this check for this section. (optional; xs:boolean),

  • residualRouteCancellationDelay: The delay after which the interlocking may clear a partial route left by an unusual train run. The timer starts running when the interlocking accepts the signal man request to clear the section (DE: Restfahrstrasse auflösen) or when the interlocking algorithm detects that the train has set back (automatic route release). (obligatory; xs:duration),

  • partialRouteReleaseDelay: Delay time after which the section may be released for use in a new route (obligatory; xs:duration),

  • technology: the technical type of the TVD section (optional; xs:string; patterns: other:\w{2,})
Possible values:
  • trackCircuit
  • axleCounter,

  • frequency: The frequency in Hertz in case of a track circuit. Shall be zero for direct current. (optional; xs:decimal; minInclusive: 0; fractionDigits: 3),

  • id: unique identifier (optional; xs:ID; patterns: (urn:uuid:)?[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}|\{[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\})
*Notice:
Elements may have different parent elements. As a consequence they may be used in different contexts.
Please, consider this as well as a user of this wiki as when developing this documentation further.
Aspects that are only relevant with respect to one of several parents should be explained exclusively in the documentation of the respective parent element.

Semantics

Best Practice / Examples

The track vacancy detection sections are a fundamental feature to monitor train positions and to ensure safety of railway traffic. Although different technologies are used for the detection itself the main features are similar for each of them. The proving of track vacancy is limited to a defined part in the track network. The limits are beside physical ones detection points or insulated rail joints (physical or virtual).

Each object <tvdSection> defines the characteristics of such a track section with the following details.

  • @isBerthingTrack – This flag marks a section where trains normally would halt and change direction. Typically, an Interlocking assures that trains progress from section to section in an ordered sequence (aka. two/three phase release). This check would fail when a train changes direction. If this attribute is true, the interlocking does not carry out this check for this section.
  • @residualRouteCancellationDelay – In case there was an unusual train run with not sequential track occupation the automatic release of the track section is not performed. The operator has to initiate this release by command. The timer is a safety precaution to make the presence of vehicles running into this section unlikely.
  • @partialRouteReleaseDelay – In most of electronic interlocking track sections are automatically released after correct sequential occupation and clearance by the train. In order to reduce the possibility of false sequences, i.e. previous section clear before next one is occupied; a timer is introduced until the release process is performed.
  • @technology – It marks the technology type of this TVD section. The possible values can be
    • axleCounter – The TVD section is formed by axel counter detection points.
    • trackCircuit – The TVD section is using track circuit equipment with insulated rail joints or virtual ones as delimiters.
    • other:… – The TVD section is made of another technology. This is the optional extension of the list. Each entry needs to start with the string “other:” and shall have at least two letters in addition.
  • @frequency – This is the frequency in Hertz of a track circuit. For DC track circuits this shall be set to zero. Omitting this value shall be interpreted as not applicable or unknown.
  • <hasDemarcatingBufferstop> – This is the reference to <bufferStop> the physical track ends like buffer stop as a limit of the TVD section.
  • <hasDemarcatingTraindetector> – This is the reference to the limiting points between track sections used for train detection <trainDetectionElement>, e.g. axle counter point, insulated rail joint.
  • <hasResetStrategy> – This is the reference to one of the defined reset strategies. The information is used for determining the related operator commands, which the interlocking shall handle for this TVD section.
  • <hasExitSignal> – This is the reference to a signal which protects the exit from this TVD section. It shall be used in case @isBerthingTrack is set to true.


Within the simple example there are different kind of TVD sections. Here is a platform track with physical track end at one side and an axle counter detection point at its other side. It is obviously a berthing track in this case and it has an exit signal. The sweep-run without confirmation is chosen as section reset strategy.

<tvdSection isBerthingTrack="true" id="A01T" partialRouteReleaseDelay="PT1S"  residualRouteCancellationDelay="PT90S" technology="axleCounter">
        <designator register="_SimpleRegister" entry="Arnau A01"/>
        <hasDemarcatingBufferstop ref="bus01" />
        <hasExitSignal ref="mb_sig02" />
        <hasDemarcatingTraindetector ref="tde01" />
        <hasResetStrategy ref="rst_swr_noconf" />
</tvdSection>

The next extract shows a TVD section with more than two ends because it represents a switch. The section limits are established by axle counter detection points. Therefore, the reset strategy and release timers are similar to the first extract. The relation to tracks in infrastructure includes all three legs of the switch because the tracks are defined until the virtual connection point of the netElements. This may be the crossing of tangents of both branches named point of intersection (de: Weichenmitte).

<tvdSection isBerthingTrack="false" id="A68W02T" partialRouteReleaseDelay="PT1S"  residualRouteCancellationDelay="PT90S" technology="axleCounter">
        <designator register="_SimpleRegister" entry="Arnau pt68W02"/>
        <hasDemarcatingTraindetector ref="tde01"/>
        <hasDemarcatingTraindetector ref="tde02"/>
        <hasDemarcatingTraindetector ref="tde03"/>
        <hasResetStrategy ref="rst_swr_noconf" />
</tvdSection>

The last extract shows a TVD section using insulated rail joints for limitation. Therefore, the conditional reset and different release timer were chosen.

<tvdSection isBerthingTrack="false" id="B03T" partialRouteReleaseDelay="PT4S"  residualRouteCancellationDelay="PT90S" technology="trackCircuit">
        <designator register="_SimpleRegister" entry="entry B03"/>
        <hasDemarcatingTraindetector ref="tde05"/>
        <hasDemarcatingTraindetector ref="tde06"/>
        <hasResetStrategy ref="rst_cd"/>
</tvdSection>

Additional Information

Notes

Open Issues