ERTMS Level 2

 
ERTMS Level 2 is a Train Control System based on data communications between the Radio Block Centre and the trains. The radio system chosen for the European Railways is GSM-R, in the 900 MHz frequency band. In this case, the Eurobalise® normally provides fixed information including acts as a position reference.
 
Main Features:

• Trackside optical signals can be eliminated or minimised (subject to operating rules)
• Conventional train detection supports train complete, interlocking and automatic block functions
• Movement Authorities are provided through GSM-R
• Train Position is calculated on-board from Eurobalise information

 
The Radio Block Centre (RBC) provides information continuously to each train and knows from trains their positions; it receives track circuits and route status information from the Automatic Block System and from Interlockings.
 
Components and functions of Central and Wayside equipment.
 
Radio Block Centre (RBC):
 

• Interface with local Interlockings to obtain track occupation and route set status, and (where supported) to provide instructions to the interlocking such as to release approach-locking controls
• Management of movement authorities for all trains within the controlled area
• Storage, management and transmission of selected trackside data
• Encryption / decryption of messages exchanged with the trains
• Communication with any adjacent RBC, with ERTMS Control Center, etc.

 
Lineside Encoder Unit (LEU):

• Generally not needed on Level 2 applications  
• Interfacing with Signals and/or with local Interlockings
• Selecting and sending telegrams that contain movement authorities and trackside data

 
Eurobalise®: 

• Stores infrastructure data as pre-formatted ‘telegrams’ (position reference, speed limits, line gradient, etc.)
• Is energised by power from train antenna
• When energised sends to train telegrams containing its fixed information (There is normally no LEU connection)

 
Mainfunctions of  On-Board equipment:

• Reception on-board from the RBC of data including movement authorities, information about the status and characteristics of the track ahead and the distance to the next balise. The train sends its position with respect to Eurobalises back to the RBC.
• Calculation of the dynamic speed profile, in relation to the train characteristics which are known on-board.
• Selection of the most restrictive speed value to be observed at the locations ahead.
• Comparison between the train’s actual speed and the permitted speed with, if necessary, mandatory brake application.
• Display of indications and provision of alerts / warnings to the driver.
• Provision of ‘planning’ information to the driver about the route ahead enabling efficient driving

 
Main ERTMS Level 2 Main Lines & Freight: