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ERTMS level 2 in stations

Presentation at Banebranchen 2017, Signalling Programme Chief Engineer Jens Holst Møller

A look at the ERTMS operational conditions in larger station areas

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Station areas

1. Data transmission capacity shall be sufficient to allow systems communications as

well as voice communication.

o Optimised network design required and migration to package switched

communication essentially best option for the entire network.

2. The operational concept and track layout in areas where trains start their mission

shall be optimised.

o Trains shall be able to start ”in the system” without written orders etc.

• Cold Movement Detection is neccesary to enable start (in OS or FS)

o Movements in controlled area shall be planned and supervised

• Avoid shunting moves outside possessions.

o Entry/exit areas for stations shall be block-optimised (low speed require

short block sections to allow high train density)

Operational capacity

Tog til/fra Kastrup

Tog til/fra Ny Ellebjerg

Tog til/fra Valby

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Data transmission capacity

– The data transmission for ERTMS is based on GSM-R. The available

bandwith is 4 MHz which equates 19 frequency slots (20 200 kHz slots

including guard band). A slot can provide 7 communication channels (two

can provide 15 and three 23)

o Voice calls occupies 1 channel each for the duration of a call. For a

larger node around 3-4 channels will be needed to serve voice calls.

o In circuit switched mode each mobile station (train) permanently

occupies 1 channel (like a non-stop voice call), in handover between 2

RBC areas 2 channels are used by the mobile station(both modems

active).

o In packet switched mode each channel can be shared between 3-5

trains and RBC handover can even be done without 2 modems active.

GSM-R cellular basis

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Data transmission capacity

– GSM-R base stations typically cover an area of 5-8 km and carry 1 or 2

frequency pairs (TRX’s).

o To achieve sufficient reliability a redundant A/B base station network is

established which traditionally doubles the operated frequencies in an area.

o In dense areas the coverage area is reduced and the number of TRX’es can

be increased to 3 to improve capacity. But less than 1000 m cells will

require special measures, and obviously increases the cost.

– The frequency plan for an area will have to take interference into consideration.

o Minimum distance between reuse of same frequency (1,2,3,1,2,3 priciple)

o Measures to control out of band interference from other systems (like

4G/LTE)

o In border zones or special geographic conditions the usage of some

frequencies can be blocked(due to interference risk)

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Example: Traffic model for Copenhagen (2013)

• A1: Tunnel section, 6 trains

• A2: Platform tracks, 18 trains

• A3: Station access, 6 trains

• A4: Depot area, 10 trains+20 shuntingmoves(~5 calls)

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Example: Cell planning for Copenhagen

Frequencies shared with Sweden so repeat pattern must bebased on max 9 frequencies

• BTS distances between 600 m and 1,2 km.

• Sites 404 and 064 have 3 TRX allowing 19 simultaneousCSD trains with4 channelsallocated for voice calls.

• 402 has 2 TRX allowing 15 CS connections

Conventional A/B redundancy clearly not feasibleHot standby principles will instead be used

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Data transmission capacity

– Station areas with more than 20 concurrent train movements

within an area of 1000 m will require packet switched data (ETCS

over GPRS/EDGE)

o ETCS over GPRS is specified in B3 Release 2 (TSI 2016/919

set #3). Changes affect:

• the ETCS onboard systems (SRS 3.6.0, implementing IP

stack, QoS parameters and PS SoM/handover procedures)

• The trackside fixed transmission (new enhanced ”ERTMS”

DNS service)

• The GSM-R network (Eirene 8.0 to implement QoS

requirements)

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Station areas -processes

– Shunting will be restricted to areas outside the operational ERTMS system,

in track possessions (TSA & PSAs using ERTMS mode SH). SH will

predominantly be used by freight trains and yellow fleet.

o Shunting in TSAs(Interlocked area) will be performed on shunting

routes set by Shunter(through Handheld Terminal using GPRS)

– All remaining movements inside the ERTMS area will be performed from

leading cab, supervised on a MA (ERTMS modes FS or OS).

– This increases speed of operations and reduces the risk of passing signals

at danger, overspeeding, damaging points etc.

– Train data is neccesary: Default traindata available in Onboard or

transmitted from train computer(depending on train type)

Operational concept and rules (how w/o colour light signals)

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Joining, splitting & Start of Mission

– In a total of 53 stations, relevant tracks will be equipped for

effective splitting and joining of trainsets

Tracks with short detection sections and extra odometry

correction balises

Only short drive in ERTMS mode OS

– At all entries to ERTMS area, position balises ensure that the SoM

happens with a ”valid position”

All trains entering the system will be able to start with a real

movement authority (MA OS or FS)

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Station areas

– Deployment is done in sections, typical boundary at the existing block-interface

to avoid transitions in stations.

– The majority of equipment is installed in parallel to the operational railway.

– Point machines and level crossing protection systems are migrated through a

combination of ”over and back” on central point machines and

migration+blocking before, respectively after commissioning

– Interfaces between migrated lines and lines with legacy signalling are divided

in two classes:

o Temporary interfaces where trains shall stop and switch over (max two

weeks)

o Interfaces where trains can transition automatically (no limit)

Migration – deployment principles