RBC and Interlocking

Contrary to traditional implementations of ETCS signaling systems, the RBC and interlocking functionalities of the Winter Train will be integrated into one system.

Positioning and Movement Authority

In order for the RBC to provide movement authorities, the position of each train has to be established with a certain accuracy.


The first version of the Winter Train OBU will establish actual position of each train by means of balises, driving direction and distance. A balise is a transponder mounted in the track. When a train passes a balise, the train will read the telegram conveyed by the balise and by this get a reference to the position. Each balise will provide a unique ID, but otherwise no specific information.

The distance will be measured by counting wheel turns. To simplify the balise system only single balises will be used. The actual driving direction will be derived from the polarity of the (direct current) traction power in the rails - i.e. whether the polarity at the right side wheels are positive or negative.

Actual train position will hence be expressed as a relative distance - with sign - from a given balise. Unit of distance will be wheel turns, assuming that the wheel diameter of the wheels are the same. A positive value will indicate, that the train is located at a position further away from the balise in direction up. A negative value will tell, that the train is located in direction down, compared to the balise.

The OBU will send a position report to the RBC at regular intervals (~2 seconds). The report will include:

  • Train ID
  • ID of most resently read balise
  • Relative distance from this balise to the train (i.e. antenna location).
  • Nominel driving direction (up or down)
  • MA status
  • Operational mode

MA status will indicate whether an MA referring to this balise is requested or, as an acknowledgement to the RBC, if an MA referring to this balise has been received.

Having only one balise reader (antenna), the OBU must calculate the position of the train front based on train length and driving direction. Engineering of OBU will include length of train and position of antenna.

Invalid position

The OBU will not keep the curent position during power down or OBU reset. After power up or re-start, the OBU will send a position report indicating the lack of valid position information. In this situation, the driver has to run the train to the next balise in mode SR or SH.

The RBC will keep the most recently received train position for a specific time (10 - 30 seconds). If the OBU restarts within this period, the RBC will assume this position as actual position of this train. If the position stored in the RBC is obsolete, the OBU will get an order to move at low speed to the first read balise.

If all trains within an RBC has no valid position, they will be requested to find the first balise by moving in the same direction.

Movement Authority

The Winter Train BRC will provide simplified MA to trains based on simplified train routes set in the interlocking. All distances will be relative (including direction) to given balises. The MA will contain a static maximum speed in the first verion of the Winter Train.

An MA allows the train to run from its actual position to a specified End Of Authority EOA. The location of EOA will be given by the RBC as the relative distance from a specific balise. This balise will be the balise reported in the most recently received position report.

An MA will consist of:

  • Train ID
  • ID of balise
  • Distance (with sign) to EOA from this balise.

The MA will be calculated by the RBC based on the actual position of the train (as reported) and the topology. The sign of the distance from the balise to EOA will explicit specify the nominel driving direction (up or down).

As the OBU may read another balise in the period between sending a position report and receiving an MA (for that position), the OBU must keep track of at least the three most recently read balises and the current distance from each of these.

Only signals, marker boards and bufferstops can be EOA.

The RBC may update the current MA, simply by issuing a new. This new MA can point at a new EOA furhter away. The RBC can withdraw an MA and can send emergency stop order to trains (more or less the same). The OBU will keep only one MA. If a new MA is received, the old will be discarded.

An MA is valid:

  • Until the train has reached EOA or
  • the MA has been replaced/updated or
  • mode SH, SR or Neutral is selected

The balise specified in the MA will normally be located behind the train, but may even be located in front of the train (if the train has changed driving direction).

The RBC will issue an MA only after reception of a position report and then only to this specific train and relative to the reported balise.

Position reports will indicate the position of the front end of the train. MA will directly reflect the signaling in the underlaying train route.

Mode Authority

The BRC will authorize which mode each train can operate in. An MA received by a train, is implicit an authorization for mode FS and ATO.

Mode SR and SH will explicit be authorized for each train.

Authorization for mode SH will include:

  • Specification of the area in which shunting is allowed.
  • Maximum allowed speed

The extend of the shunting area will be specified as a set of distances (with sign) from balises to the borders of the shunting area.

User interface

The RBC will have a simple WEB-based user interface. This web-page will indicate the latest received position report.

Railway topology

The railway topology will be represented in the RBC as one graph of nodes common for both directions. Following type of nodes will be used:

  • Signal / marker board (directional)
  • Bufferstop
  • Level Crossing
  • Point
  • Fouling point
  • Balise

Positions in the topology will be represented as relative distances between neighbor nodes.


Train Route

The train route concept of the Winter Train will be based on a direction specific element route:

  • from starting signal to destination signal or
  • from starting signal to destination bufferstop.

Routes will not contain intermediate signals for the actual direction. More routes can be set after each other forming longer compound routes. However no additional functionality will be provided for compound routes.

Route Release

The RBC will provide train position and stand still information to the interlocking sub-system for route release and emergency route release. The actual route will not be released under the train even if at stand still. A route can only be emergency released if no train is occupying the route. Sequential route release will be provided in order to allow release of points behind the train. This is required to enable passing stations with only one signal (per direction) between the points. The position of the fouling point will be used for this feature.


A start signal will open given:

  • A route is set from the start signal
  • All points in the route are supervised in the correct position.

The start signal will close when:

  • A train has passed the signal or
  • the route is released

Level crossing

Level crossing activation and deactivation will be based on train position and driving direction.

One location at each side of a level crossing will be specified as the trigger point for closing the level crossing. When a train is passing such a location in direction towards the level crossing, the crossing will be closed. Similar for opening the crossing.

Engineering rules

Minimum two balises shall be engineered between any two signals or between a signal and a bufferstop.

EOA will be engineered round 20 cm in rear of the signal.

it/wintertrain/design/rbc/start.txt · Last modified: 2016/10/01 11:19 by jabe