Position report

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Operation of ETCS Level 2 (variant without light signals): The train received position reports to the distance (u a..).

In the European train control system ETCS ( ETCS Level 2 and 3 ), a data packet regularly transmitted from the train to the route is referred to as a position report . The position report is the most common data package in level 2/3 and part of most messages from the train to the track.

purpose

With the position report, the train informs the route of the position of its head. At least the following data is transmitted:

According to the ETCS specification, the approximate position of the Zugspitze (estimated position) should be determined by odometry for less than a second before the position report is sent. The German web goes out of 1.5 seconds, which lie between the use of one balise group and the transmission of the location report by the vehicle device.

trigger

The ETCS center informs the ETCS in-vehicle equipment when this position should send reports. Temporal and spatial cycles can be defined as well as the travel to certain places. In addition, a position report can be made for each passage of a relevant balise group (LRBG) and upon request. Combinations are also possible, but not from the two last-mentioned triggers. For this purpose, packet 58 ( Position Report Parameters ) is used, which is transmitted from the RBC to the train. Time values ​​from 0 to 254 s (in second steps) or distances from 0 cm to 327.660 km (in 10 cm, meter or 10 meter steps) can be specified. The position report parameters are not part of the national values .

In addition, the ETCS vehicle equipment should send a position report if:

  • the train comes to a standstill (depending on the ETCS operating mode ).
  • the ETCS operating mode is changed.
  • the driver confirms the train integrity.
  • the train integrity no longer exists.
  • the train has passed an RBC-RBC boundary with the earliest possible position of the end of the train in the direction of travel ( min safe rear end ).
  • the train changes from level 2 or 3 to 0 , 1 or NTC (national train control, e.g. PZB ) with the earliest possible position of the end of the train in the direction of travel ( min safe rear end ) .
  • the level is changed.
  • a communication connection is successfully established.
  • the train passes a relevant balise group (LRBG).
  • the train passes an RBC-RBC border with the earliest possible position of the Zugspitze in the direction of travel ( max safe front end ).
  • an error has occurred.

construction

The “ETCS language” defines the communication between the train and the line. Their smallest units are variables that are transmitted as part of packets. Packets are grouped into defined messages for transmission on the air interface.

The Position Report packet is managed as packet 0 in the ETCS specification and is up to 137 bits long.

A special form of the position report is the position report based on two balise groups (package 1). This is used if the ETCS on-board device cannot determine the direction in which the last relevant (LRBG) and balise group consisting of only one balise was traveled and there is no further information on the direction of travel (via chaining ). With this special form, the balise group traveled in front of the LRBG is also evaluated in order to determine the direction of travel of the train.

The current version of the ETCS specification only provides for five messages that do not also include a position report. An ETCS message in which only a position report (packet 0 or 1) is transmitted is referred to as a train position report (message 136). A position report as part of the start procedure of the ETCS on- board unit is transmitted as a SoM position report (message 157) and contains additional information as to whether the position report is valid, invalid or the status is unknown. (The status can be invalid or unknown if the On-Board Unit has possibly been moved since the last position recorded by the ETCS On-Board Unit.)

In addition to the train position report (message 136) or SoM position report (message 157), error data (package 4), the train number (package 5) or other data used by peripheral systems (package 44) can also be transmitted.

function

The position report is transmitted from the ETCS on-board device by radio (usually GSM-R ) to the ETCS control center (RBC). It can be processed there, for example, to monitor the activity of the radio link, to assign the starting train to the track or to decide when a train has entered the area of ​​the receiving RBC in order to make the connection to the transferring RBC.

Train routing can also be carried out on the basis of position reports. For example, in the largely single-track Lötschberg base tunnel, a control system processes position report data in order to recommend a speed to trains via ETCS text messages, in order to use the single-track section as efficiently as possible and to avoid unnecessary braking and acceleration.

In ETCS Level 3 , a position report with confirmed train integrity is required to report sections of the train heading . The last possible position of the train in the direction of travel ( min safe rear end ) for the time at which integrity information was available is always reported . This position is behind the actual position of the train. The train integrity information can be provided by an external device or by the driver, although confirmation by the driver is only permitted when the vehicle is stationary.

Web links

Individual evidence

  1. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.1.1
  2. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.1.2
  3. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.2.3
  4. ↑ ETCS specification , subset 041, version 3.2.0, section 5.3.1.3
  5. ↑ Study on the introduction of ETCS in the core network of the Stuttgart S-Bahn. (PDF) Final report. WSP Infrastructure Engineering, NEXTRAIL, quattron management consulting, VIA Consulting & Development GmbH, Railistics, January 30, 2019, p. 259 , accessed on April 28, 2019 .
  6. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.1.5 in conjunction with 3.6.5.1.4
  7. ↑ ETCS specification , subset 026, 3.6.0, section 7.4.2.15
  8. ↑ ETCS specification , subset 026, 3.6.0, section 7.5.1.143
  9. ↑ ETCS specification , subset 026, 3.6.0, section 7.5.1.3
  10. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.1.4
  11. ↑ ETCS specification , subset 026, 3.6.0, section 7.3 and 8.4.1
  12. ↑ ETCS specification , subset 026, 3.6.0, section 7.4.3.1
  13. ↑ ETCS specification , subset 026, 3.6.0, section 3.4.2.3.3
  14. ↑ ETCS specification , subset 026, 3.6.0, section 8.4.4.7.2
  15. ↑ ETCS specification , subset 026, 3.6.0, section 8.6.4
  16. ↑ ETCS specification , subset 026, 3.6.0, section 8.6.15 with 7.5.1.134
  17. ↑ ETCS specification , subset 026, 3.6.0, section 8.4.4.4.2
  18. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.2.4 / 5 + figure 15
  19. ↑ ETCS specification , subset 026, 3.6.0, section 3.6.5.2