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Time to disappoint DfT Rail's new age hippy-techies
In his Presidential Address to the IRSE, Wim Coenraad gave a painfully homiest appraisal of the European Rail Traffic Management System (ERTMS) and its signalling component the European Train Control System (ETCS). His presentation was uniquely informed because Wim has been involved from the beginning, nearly 18 years ago, when the International Union of Railways formed the ERRI 200 working party to produce the specification for ETCS. The target date for entry into service was 1996.
Wim's paper was honest, and also brave, because there has been a tendency among UK railway signal engineers not to criticise ERTMS in public. Historically, this was because ERTMS was identified as the only way forward in the Joint review of train protection. To suggest that ERTMS was not going to be available when predicted, and was still unaffordable, would have brought the shroud wavers out in force.
Even now, despite the success of TPWS in reducing SPAD risk, it has taken a Dutchman to tell it how it is and express concerns about the pan European signalling system. Which is not to say that ETCS, at least, isn't happening and won't be the control system of the future – if only because of the substantial development cost already sunk.
Since 1995, Euros 367 million has been spent on ERTMS related development, including Euros 187 million from the European Trans European Networks ( TEN ) fund. If you add the money spent by the train operators, Wim Coenraad reckons that a conservative estimate for the cost of ERTMS to date is around Euros 500 million. Another Euros 500 million for ERTMS fitment is in the TEN budget for 2007-2013. Even our modest Early Deployment Scheme ( EDS ) on the Cambrian line is budgeted at £60 million.
Meanwhile in the Railways White Paper published in June and the supporting Rail Technical Strategy (RTS), DfT Rail's aspirations for ERTMS are as wide as their understanding is shallow. If they are not to be blamed as ‘wreckers' in the show trial which will surely follow the inevitable disappointment, UK signalling engineers should even now be stiffening the sinews and summoning up the blood to follow Wim's lead and give an honest appraisal of what ERTMS can offer in the foreseeable future.
Of course, they won't, preferring to encourage this column as the ‘forlorn hope'. So here goes.
First of all we need to clear up confusion over terminology. Everyone talks about ERTMS, but this is the overall system which adds a management layer to the train control provided by ETCS. This management facility does not yet exist. Thus from now on I will refer to ETCS. Yes, it's pedantic, but accurate definition is important.
ETCS is available in two levels. Level 1 provides basic Automatic Train Protection as we know it. Balises – electronic beacons - are mounted on the track and connected to the next signal. As a train passes overhead the balise transmits two sets of information to the on-board equipment – one variable, one fixed.
First, the balise provides the target speed at the signal ahead. This can be line speed if the signal is green, zero if the signal is at danger or somewhere in between if the signal is at caution. A display on the driver's desk – the posh name for which is the Man Machine Interface(MMI) – presents the target speed.
Fixed data include the location of the balise, so that the train can reset its odometer, the distance to the next balise and topographical information on the section ahead, such as the gradient. This information allows the on-board equipment to calculate the braking curve the train must follow to achieve the target speed at the next signal.
If the train strays outside the braking curve the driver is warned. If the driver does not respond the brakes are applied.
Economies of scale are starting to make ETCS Level 1 an attractive way of overlaying ATP on existing signalling. Belgium , Luxembourg and Switzerland are doing just this'
So ETCS Level 1 provides the basic ATP, of the type in use on Great Western and Chiltern routes since 1994. Level 2 is where the misunderstandings are rife.
According to Wim Coenraad Level 2 was originally nothing more than an intermediate step between the intermittent ATP provided by Level 1 and the ‘paradise' promised by Level 3. The word purgatory for this intermediate state springs to mind.
As with Level 1, Level 2 uses the standard balises, but these transmit only the fixed information. Train detection continues to be provided by track circuits or axle counters and these are connected by lineside communications links to interlockings.
So all the costly, and failure prone, lineside kit we have today is retained with Level 2, except for the signals themselves. Instead of the interlockings driving lineside signal aspects, they communicate with a Radio Block Centre ( RBC ).
Since the RBC knows the block section occupied by each train it can regulate train speeds to ensure safe separation. Individual target speeds are transmitted by radio to each train and displayed on the MMI.
If you substitute coded track circuits for radio, this is what the French TVM430 already does on the Channel Tunnel Rail Link In European terms ETCS is a replacement, not an advance.
Finally, there is, or rather, isn't, Level 3. This is the signalling equivalent of the Philosopher's Stone.
No signals, no train detection, no lineside kit at all, except, presumably, interlockings for switches and crossings. Each train determines its own location, probably still updated by balise, and transmits this to the RBC .
Since the RBC ‘knows' the location and speed of all trains it will, so the theory goes, be able to calculate the movement authority for each train based on its speed and the distance to the back of the train in front.
So, in theory, you can run trains closer together compared with boring old block sections, increasing capacity, as well as getting rid of all the lineside clutter. DfT Rail has bought this seductive vision hook line, sinker and reel. Sadly, as Wim Conenraad told me, ‘there is no Level 3 – industry is not developing it'.
And if it did exist, practical signal engineers, who tell me what they won't say publicly, raise various doubts. The first is that fixed block signalling is pretty efficient already.
Ride in the cab into Waterloo or Victoria in the peak and you can experience the theoretical benefits of Level 3 in practice today. With multiple aspect and optimised block lengths, a driver running steadily on double yellows can see the tail lamp of the train in front running at the same speed. How much closer do you need to get?
One of the big lies of today is that on 125mile/h lines fixed block signalling means that trains have to run 7.5 miles apart, leaving wasted capacity between.
Total rubbish of course, given that the theoretical minimum headway on, say, the West Coast Main line is 110 seconds. The 7.5 miles is courtesy nervous planners building in some comfort.
Of course, on the East Coast, and was it not ever thus, they have a more robust approach. Back in 2005, the 13.30 Kings Cross Edinburgh was timed to run non-stop to Retford at an average of 109.4 mile/h. Behind it, the 13.34 Hull Trains service was timed at 109.1 mile/h to Grantham. In the current timetable these timings are eased by 2min and 3min respectively.
In September 2005, John Heaton and Paul Walker each timed one of the trains on the same day.. The joint log is fascinating, showing the two trains racing along under two minutes apart between New Southgate and Yaxley and between 112 and 114 seconds after Arlesey – at 125 mile/h that's about 4 miles.
As John Heaton observes, the signal spacing on this section of the ECML is typically 0.8 miles. With four aspect signalling the sequence is train, green, green, yellow, double yellow, red, 200 yard overlap, train ahead. In other words four blocks plus the overlap or just under 3.25 miles. So, once again, the question is how close do you want to run?
With long block sections Level 3, if it existed, could certainly help. But where block lengths are already optimised, and timetable planners, engineers and operators have confidence in one another, moving block has limited value on the main line.
And if you already timetable conservatively because you are worried about things failing, think on. If the Level 3 railway comes to a halt, how do you recover if the trains are stacked back along the line and don't ‘know' where they are.
And there's also the fact that while GSM-R can just about cope with the demands of ETCS Level 2 on main lines, it will run out of bandwidth in busy areas with lots of trains having to be controlled. You really need GPRS for Level 2, let alone Level 3 to handle a major throat.
So it's Level 2 for the foreseeable future. And even then there are problems. Remember that ETCS is not about signalling, it does nothing new. ERTMS and ETCS are driven by interoperability.
This means that a Bombardier balise has to be able to talk to an Ansaldo on-train system which is communicating with a Siemens RBC . The key to this is the System Requirement Specification, or ERTMS/ETCS ‘baseline', which defines the many interfaces.
In Holland the new HSL Zuid was fitted with ETCS using Version 2.2.2 of the baseline. Belgian Railways, starting later, adopted Version 2.3.O for the line from the Dutch border to Brussels .
Bad move. When the interim service started the loco-hauled NS Hispeed trains were able to communicate happily with the Alcatel Version 2,2.2 RBCs between Amsterdam and the Belgian border. But once on Belgian rails the Version 2.3.0 RBC was incompatible.
All was not lost because ETCS degrades gracefully, and Level 2 reverts to Level 1. With the aid of the block marker boards the NS Hispeed trains can run in Belgium at 100mile/h and six minute headways. The upgrade to Version 2.3.0 is costing NS Euros 30 million.
Meanwhile, in Europe , the latest development is funding for the accelerated fitment of ETCS to six corridors which carry 20% of current freight traffic. And as you can see it is all Level 1 or 2.
Table 1
| ETCS priority corridors | ||
| Route | ETCS Level | Completion |
| Rotterdam-Genoa | 2 | 2015 |
| Stockholm Napoli | 2 | After 2020 |
| Antwerp-Basle-Lyon | 1 | 2017 |
| Valencia-Lyon-Ljubljana | 1 | 2016 |
| Desden- Prague - Vienna- | ||
| Bratislava-Budapest | 2 | 2020 |
| Duisberg-Berlin-Warsaw | 2* | 2020 |
*Polish Level and completion date unknown
Reading the Railways White Paper published in July you would not recognise the current state of ERTMS/ETCS development described above. I quote:
By the second half of the next decade and continuing thereafter, cab-based signalling will be implemented on a greater proportion of the network. This will increase capacity by allowing a higher frequency of train service, while maintaining safety. Trains will ‘know' the position and speed of the trains in front of them, and will not require the 7 1 / 2 mile gaps between services that are standard on inter-city routes today'.
There is no polite way of putting it. This is total b*ll*cks.
Just to be sure, I checked which Level would provide this facility? After a pause I was told Level 2.
But even under Level 3, the train has no ‘knowledge' of the ‘position and speed of the train in front'. All it knows is its own position and speed and the last movement authority received from the RBC . As its name implies it is the RBC which determines safe separation and one day an RBC might be able to take into account relative speeds, but not by the second half of the next decade.
With Level 2, while the signals may not be there, you still have block marker boards and the RBC maintains safe separation in terms of occupied ‘blocks', whether defined by track circuits or axle counters.
I will leave it to my chum at the other end of the magazine to deconstruct a second passage from the White Paper, which I also checked assumes Level 2. ‘ Electrification would be more cost-effective if it were implemented following the migration to radio-based cab signalling. One of the most serious practical problems with electrification is to prevent it interfering with the existing wire-based signalling system'. Over to you, Alan.
As I said at the beginning, all this does not mean that we can, or should, avoid ETCS. It is mandated by Europe . The he timetable for the implementation of ERTMS in the UK , following on from the EDS , has to be submitted to the EU this month.
Network Rail is developing the timetable which will take account of the ‘potential for long-term cost reductions and capacity increases offered by ERTMS', says the White Paper. It will also include the ‘opportunities for implementation alongside the delivery of new rolling stock and the re-signalling of Great Western and East Coast main lines between 2014 and 2020'.
In fact, the latest electronic interlockings are ‘ETCS ready', since the ability to communicate with an RBC is built in. Fitting the trains is elephant in the room.