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"Electronically controlled pneumatic" braking, a system with a power and data base running the length of the train that allows independent electronic control of all brakes in the formation, and data passage between vehicles and the locomotives. The air brake pipe is retained solely as a method of continuously refilling the reservoirs in the vehicles. It's been deployed on some heavy haul railways in Australia, South Africa and North America but the up front cost of mass retrofit has held it back elswhere.
With such a system you can provide continuous train completeness checks, transmit multiple working data and any number of other things.
This does sound like a solution if not a simple one. But likely still cheaper and easier than equipping all freight wagons with transponders or using a dedicated trailer.
The problem AFAICS will be getting the whole fleet equipped, with the fragmented ownership and maintenance of wagons. Think NR/GBR will need to take a lead here.
For older freight locos that do not have any form of electric brake control, the ETCS service brake command will interface with the air brakes by means of an electropneumatic system.
For locos with electric brake control, Freight ETCS will replicate a driver's full service brake application.
Freight ETCS does not include any provision for electronic control of wagon brakes, but in any case, ETCS intervention is (certainly at Level 2) only a last resort in response to driver inaction.
The reason I was suggesting ECP brakes is it would allow for electronic, on board, checking of train integrity.
That could allow dramatic simplification of trackside infrastructure because the number of axle counters (and all their supporting infrastructure) could be slashed.
That would save costs and reduce the workload in resignalling projects by rendering them less complex.
The reason I was suggesting ECP brakes is it would allow for electronic, on board, checking of train integrity.
That could allow dramatic simplification of trackside infrastructure because the number of axle counters (and all their supporting infrastructure) could be slashed.
That would save costs and reduce the workload in resignalling projects by rendering them less complex.
The problem I see is the FOCs don't make any profits so don't have enough money to invest. So a funding mechanism (e.g. via TACs) will be needed to allow the equipping of freight stock to be financed from the savings made in fixed infrastructure. Overall the railway and country will then benefit from the efficiencies thus made available.
The problem I see is the FOCs don't make any profits so don't have enough money to invest. So a funding mechanism (e.g. via TACs) will be needed to allow the equipping of freight stock to be financed from the savings made in fixed infrastructure. Overall the railway and country will then benefit from the efficiencies thus made available.
Estimates are about $40,000 per locomotive and $4,000 per wagon. The highly uniform nature of the locomotive fleet (dominated by a small number of classes) might help there.
But getting a good estimate on the size of the active freight fleet is really difficult. But given that, even with ETCS, a singel signalling equivalent unit costs ~£300-400k, I don't think its unreasonable to come to the conclusion there could be a net saving to society.
But working out a funding mechanism is the biggest challenge, as you say.
The EU has been grappling with ETCS for freight as well as measures to remove human error arising from the coupling/uncoupling function. They are proposing "digital automatic couplers" (digital with everything these days it seems). This initiative would allow power and control circuits to be provided down the train enabling the train integrity function and possibly electro-pneumatic brakes.
Fitting ETCS to freight locos, EP brakes to the wagons and autocouplers to everything will cost serious money and I think HSTEd's estimate is at the low end.
But there is value in improving the braking curve of freight trains which would be directly enabled by EP brakes, and the lack of train integrity on freight trains is a major barrier to the deployment of ETCS level 3 which has the potential to improve the capacity of lines. Whether one offsets the other is another matter.
Why convert the braking system, when surely it will be cheaper to update/modify US-style end of train devices to positively feedback their position to the loco and interlocking?
Why convert the braking system, when surely it will be cheaper to update/modify US-style end of train devices to positively feedback their position to the loco and interlocking?
How will they positively, and reliably, feedback their position with sufficient accuracy to satisfy signalling requirements about train continuity?
And how much will the development scheme for this cost, and how many years will it take?
The advantage of an ECP brake solution is the system already exists.
Fitting 1000 locomotives and 20,000 wagons (as random example) is only going to come to ~$120m based on US experience.
Any kind of major development programme is going to blow through that in short order, especially considering delays.
No idea, but it's based on an existing technology that's already in widespread use in the US, and UK trains currently run with a end-of-train marker, so it's just an upgrade.
The advantage of an ECP brake solution is the system already exists.
Fitting 1000 locomotives and 20,000 wagons (as random example) is only going to come to ~$120m based on US experience.
Any kind of major development programme is going to blow through that in short order, especially considering delays.
The disadvantage of it is ECP brake systems require taking wagons out of service to fit, and somebody's got to come up with the money to fit them.
ECP will have a place, but I wouldn't expect every single wagon to be retrofitted with such a system if somebody can effectively develop a 'smart' Tail Lamp.
GSM-R, GPS, the brake pressure and possibly a data connection to the loco's Doppler radar (when they come in)
No idea, but it's based on an existing technology that's already in widespread use in the US, and UK trains currently run with a end-of-train marker, so it's just an upgrade.
The disadvantage of it is ECP brake systems require taking wagons out of service to fit, and somebody's got to come up with the money to fit them.
ECP will have a place, but I wouldn't expect every single wagon to be retrofitted with such a system if somebody can effectively develop a 'smart' Tail Lamp.
Also modern EOT devices used in the USA typically have two way radio comms set up with the active cab, relaying brake pressure and positional info from the rear and having a remote-controlled brake valve to apply braking from both ends of the train simultaneously. Also incorporating a 'near field' reader for balise-based rear-end positioning seems a plausible upgrade.
Also modern EOT devices used in the USA typically have two way radio comms set up with the active cab, relaying brake pressure and positional info from the rear and having a remote-controlled brake valve to apply braking from both ends of the train simultaneously. Also incorporating a 'near field' reader for balise-based rear-end positioning seems a plausible upgrade.
Would power consumption not be an issue for what's presumably a battery powered device? Balise readers supply power via an RF carrier to energise the balise so I presume they need to transmit this continuously. I'd assume the weight of the device + battery will be limited by what can be carried and fitted by shunter personnel e.g. if the Locomotive does a run-around.
I guess the issue is that without end of train detection (i.e using just the locomotive + train integrity) a train cannot 'prove clear' to the signaling system until it reaches the next balise, which would lengthen the headway. But - making a reasonable assumption that passive balises are much cheaper to install than lights on sticks - shorter blocks may mean it's not really a problem.
Would power consumption not be an issue for what's presumably a battery powered device? Balise readers supply power via an RF carrier to energise the balise so I presume they need to transmit this continuously. I'd assume the weight of the device + battery will be limited by what can be carried and fitted by shunter personnel e.g. if the Locomotive does a run-around.
I guess the issue is that without end of train detection (i.e using just the locomotive + train integrity) a train cannot 'prove clear' to the signaling system until it reaches the next balise, which would lengthen the headway. But - making a reasonable assumption that passive balises are much cheaper to install than lights on sticks - shorter blocks may mean it's not really a problem.
EOTDs have batteries for their energy needs which are typically topped up by a small generator powered by the brake line air. I don't know if the additional demand of a balise reader would be a deal breaker. I think passive balise spacing has to be a certain minimum in Level 2+ to ensure accuracy as their known fixed positions help correct onboard odometry. The capacity of fixed block 4-asp. signalling cannot be improved much by moving block on main line multi traffic railways, apart from around station platforms where extreme closing up might be allowed selectively so a fixed virtual block system with fairly short blocks is optimal, IMHO.
Also modern EOT devices used in the USA typically have two way radio comms set up with the active cab, relaying brake pressure and positional info from the rear and having a remote-controlled brake valve to apply braking from both ends of the train simultaneously. Also incorporating a 'near field' reader for balise-based rear-end positioning seems a plausible upgrade.
Fitting a balise reader with sufficient directionality to read only balises under the train seem might be a bit of an issue for a unit that is not integrated with the train as a whole.
It's got to read the correct balise every time after all.
It's probably doable but I have to ask how many years and how muhc money will be spent on such a solution to avoid the cost to just do it now and start reaping the benefits.
There is also the procedural question of developing a sufficiently robust method of determining train length - whereas in a cable ECP system you know the list of vehicles in the formation and each vehicle can be expected to know its own length.
ETCS level 2 only needs train length for acceleration point calculations - and current implementations satisfactorily rely on driver input for that; and that input isn’t validated against the actual train formation (at least it isn’t on 387s) - You can “start of mission” as a 4 car even when the actual train formation is 8 car.
Yes, level 3 where traditional train detection is done away with and train position is reported via ETCS would require it; but are there any serious proposals for Level 3 anywhere? Even in Europe? Especially where you can achieve almost all the performance benefits with short virtual blocks in Level 2 (see the Thameslink core implementation where you have much shorter ETCS-only blocks between traditional lights on sticks)
Until there’s a serious consideration to implement Level 3 somewhere; I’m not sure freight wagons need any modifications to run under ETCS Level 2, as long as the loco is suitably equipped to receive and display movement authorities.
Fitting a balise reader with sufficient directionality to read only balises under the train seem might be a bit of an issue for a unit that is not integrated with the train as a whole.
It's got to read the correct balise every time after all.
It's probably doable but I have to ask how many years and how muhc money will be spent on such a solution to avoid the cost to just do it now and start reaping the benefits.
There is also the procedural question of developing a sufficiently robust method of determining train length - whereas in a cable ECP system you know the list of vehicles in the formation and each vehicle can be expected to know its own length.
EOTDs are usually attached at coupler/brake pipe level. A notional balise reading variant might project downwards to allow the actual antenna to be mounted at a conventional distance from the track balise, just as if it was mounted under the vehicle. Maybe a special bracket would need to be developed, better than a standard lamp iron lug, that firmly locks the device accurately into place so it can't move out of optimal alignment.
A rear-end reader could confirm the end of the train had passed a particular position and thus that the whole train has cleared a particular block. That is similar in principle to observing taillights in a manual absolute block section, although in this case the train would know its rear had passed the particular balise and would report that back to the interlocking via train radio. The rear balise reader clearance method doesn't need the train to determine its own length explicitly nor even to monitor completeness. Trains have always monitored completeness in the sense that if the continuous brake line is interrupted then the brakes come on, albeit noting that in a traditional pneumatic setup that can be quite a slow application, especially with single pipe. So both halves of a split train will come to a stand eventually and if the rear hasn't cleared a particular block, then that block stays occupied.
A simple ECP brake would not need to exchange lots of data with individual wagons, only monitor completeness of the entire line and issue the brake commands one way. That's not to say some diagnostic data couldn't come back the other way to report faults on individual vehicles and that needn't be just braking issues but could include hot box monitoring etc.
Not 'real' L3, but there are multiple countries (the UK included) that are proposing a hybrid Level 3. This uses L3 features to create very short virtual blocks instead of the moving blocks from L3, while trains with 'only' L2 support will still be able to use the track-side equipment. This means that there can be a capacity increase in general, while still being able to fall back to the 'older' L2 for trains that don't support L3 features.
I don't know where the other countries stand, but here in the Netherlands there has been a proposal for a functional L3 hybrid trial to start in about 5 years time (but we all know how that works on the railway, so I'll be surprised if it'll be before 2030 ).
Until there’s a serious consideration to implement Level 3 somewhere; I’m not sure freight wagons need any modifications to run under ETCS Level 2, as long as the loco is suitably equipped to receive and display movement authorities.
A rear-end reader could confirm the end of the train had passed a particular position and thus that the whole train has cleared a particular block. That is similar in principle to observing taillights in a manual absolute block section, although in this case the train would know its rear had passed the particular balise and would report that back to the interlocking via train radio. The rear balise reader clearance method doesn't need the train to determine its own length explicitly nor even to monitor completeness. Trains have always monitored completeness in the sense that if the continuous brake line is interrupted then the brakes come on, albeit noting that in a traditional pneumatic setup that can be quite a slow application, especially with single pipe. So both halves of a split train will come to a stand eventually and if the rear hasn't cleared a particular block, then that block stays occupied.
This is exactly what I was thinking about, since the premise of this discussion started (on the other thread) with what's needed to eliminate costly fixed train detection (i.e. track circuits) while maintaining absolute block.
The brake pipe will bring a divided train to a stop but it's too slow acting and variable to be used for reliable position indication of detached wagons (i.e block occupation)
An EOT balise reader would be the optimum, but it would also be possible to synthesize end of train location using a combination of locomotive position & train integrity, provided that the latter was updated very frequently (from EOT device to Locomotive) because the locomotive cannot send a 'block clear' message until it's confirmed that it's traveled the length of the train (past the end of the block) and that the consist is still intact at that point.
But the other issue with a synthetic data system is that it would be dependent on manually entered train length data, so perhaps there is no failsafe way to avoid either an EOT balise reader or continuously wired consists. An EOT device would be much cheaper and easier to implement, assuming the technical hurdles can be overcome.
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Until there’s a serious consideration to implement Level 3 somewhere; I’m not sure freight wagons need any modifications to run under ETCS Level 2, as long as the loco is suitably equipped to receive and display movement authorities.
True, the point being discussed is the opposite conundrum that (cost saving) L3 implementations cannot be seriously considered until freight (and indeed any other locomotive hauled) consists are suitably equipped.
or if you like it's a dependency that must be met to reach a desirable goal.
Yes, level 3 where traditional train detection is done away with and train position is reported via ETCS would require it; but are there any serious proposals for Level 3 anywhere? Even in Europe? Especially where you can achieve almost all the performance benefits with short virtual blocks in Level 2 (see the Thameslink core implementation where you have much shorter ETCS-only blocks between traditional lights on sticks)
Until there’s a serious consideration to implement Level 3 somewhere; I’m not sure freight wagons need any modifications to run under ETCS Level 2, as long as the loco is suitably equipped to receive and display movement authorities.
The advantage of moving to onboard train detection systems not additional capacity.
The objective of the discussion in this thread is to allow the elimination of a very large fraction of the remaining trackside infrastructure by removing the need for most of the fixed trackside train detection infrastructure and all its associated hardware.
All that hardware is enormously expensive to design, install, commission and maintain
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But the other issue with a synthetic data system is that it would be dependent on manually entered train length data, so perhaps there is no failsafe way to avoid either an EOT balise reader or continuously wired consists. An EOT device would be much cheaper and easier to implement, assuming the technical hurdles can be overcome.
That's just because the implementation difficulties are not in the implementation, but in creating such a system in the first place.
The advantage of the ECP braking solution is it exists, you can go to NYAB or similar vendors and buy it.
As far as I am aware no-one has created a balise reading end of train device or has even attempted to do so.
It's all very well hoping that some future technology will avoid expenditure in the present - but this can just lead to paralysis where nothing happens and the benefits we could get now don't arrive because the hyper-tech doesn't arrive as hoped.
The advantage of moving to onboard train detection systems not additional capacity.
The objective of the discussion in this thread is to allow the elimination of a very large fraction of the remaining trackside infrastructure by removing the need for most of the fixed trackside train detection infrastructure and all its associated hardware.
All that hardware is enormously expensive to design, install, commission and maintain - and requires lots of trackside power cables that are constantly being stolen.
Being cynical, it also removes a lot of the infrastructure owner’s cost and makes it a train operator’s problem. There would need to be a revision of the infrastructure usage fees to reflect that.
It’s the same reason (but in reverse) why NR was against electrification for so long.
That's just because the implementation difficulties are not in the implementation, but in creating such a system in the first place.
The advantage of the ECP braking solution is it exists, you can go to NYAB or similar vendors and buy it.
As far as I am aware no-one has created a balise reading end of train device or has even attempted to do so.
It's all very well hoping that some future technology will avoid expenditure in the present - but this can just lead to paralysis where nothing happens and the benefits we could get now don't arrive because the hyper-tech doesn't arrive as hoped.
I don't disagree at all with any of that, but history shows many times that things tend to follow the money. Many tech-wiz proposals fall flat because they fail to properly account for the economics.
The trade-off here is the costs to equip and maintain thousands of wagons with ECP, vs a single EOT device per train, that can be used with any existing conventional wagons without significant modification. The freight market is volatile and ownership & maintenance of wagons is highly fragmented, so ECP would involve a large commercial risk for many different parties to invest in equipping their fleets, which is a big ask for an industry reluctant to even invest in new locomotives. So if (big if) an EOT device solution turns out to be technically viable it will likely be what's selected, and the potential for substantial cost savings provides a strong motive to invest in developing it.
Of course it's also possible that both solutions may coexist. ECP may offer other benefits to justify the additional cost, such as reduced brake/wheel wear and improved asset monitoring.
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I don't know the actual costs, but it's not unreasonable to assume that the overall costs of infrastructure based block detection are at least an order of magnitude greater than a train based solution, and enablers like the GSM/R network already exist.
Plus NR/GBR have much more clout than the FOCs to make things happen, even if it means somehow paying the FOCs to deal with it.
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