Do MUs still need two cabs?

[andy33gmail]

The original reason for a cab at end end of a MU is obvious; you can drive it in either direction without another loco or someone manually calling you on

However, multiple CCTV streams can and are used for train operation anyway, e.g. driver only dispatch.

Would it be feasible to design a train with one cab, and a very good system of cameras and screens, to allow safe, reliable and ergonomic operation? You’d have to effectively define the vehicle as “broken down” if they failed of course.

It would free up space, and offer options - e.g. a wide gangway on one end and an uncramped cab on the other for example

I suspect there are operational considerations that would need reworking - e.g. stepping out for a token on very remote lines, stepping off at a short platform

 

[Harpo]

Or no cabs, driver gets a soundproof cupboard somewhere in the middle of the train. I’m sure ASLEF would love it.

 

[Zomboid]

If it can be done reliably then there's a case to be made, though I suspect the cost of implementing a system with high enough reliability would exceed that of providing a second cab.

Potential for motion sickness too, as the monitor feed won't be exactly in sync with the movement of wherever the driver is.

 

[gazthomas]

If you do this why not just have remote drivers, like they have with, for example, military drones. This would require unbelievably robust telecoms!

 

[Sun Chariot]

Hello @andy33gmail -
The "field of clear vision" offered through a forward-facing window, is still far superior to looking at a monitor-screen.

- The screen gives less ease at spotting the tiny things in the distance (such as person trackside, vehicle on a crossing).
- Even 120-150Hz, a screen has an inherent eye-fatiguing screen flicker.
- What fail-over / fail-safe, for a loss of comms or hardware? Even a momentary loss of vision, is a safety-risk (i.e. missed signal).

 

[172007]

The cabs on modern trains are designed as crash zones, certanly on higher speed stock so you would still end up with that space lost to passengers. Two cabs gives you a chance to clear the line if one cab becomes defective or bury the cab between units and still have in service.

 

[daodao]

There are other options if there is just a driving cab at one end, such as a loop or reversing triangle at the terminus, as used on many electric tramways, particularly in continental Europe. Historically, the County Donegal Joint Railways Committee lines had turntables at their termini for their single cab railcars.

 

[stevieinselby]

There are other options if there is just a driving cab at one end, such as a loop or reversing triangle at the terminus, as used on many electric tramways, particularly in continental Europe. Historically, the County Donegal Joint Railways Committee lines had turntables at their termini for their single cab railcars.

How would a turntable work with a single-cabbed 12-car Thameslink train – are you going to have a 250m wide turntable? Likewise a reversing triangle to accommodate longer trains is going to take up a lot of space, and loops are similarly huge (whatever length train you need to turn). The idea of fitting that kind of provision at every point where you might need to reverse a train is absolutely mad (and with terminus stations, you would need to have a way to drive trains in reverse safely, either in or out of the station). The costs and difficulties that removing cabs from one end of multiple units would be many, many orders of magnitude higher than the cost of including a cab at each end. Why do we even entertain such ridiculous ideas?

 

[Zomboid]

How would a turntable work with a single-cabbed 12-car Thameslink train – are you going to have a 250m wide turntable? Likewise a reversing triangle to accommodate longer trains is going to take up a lot of space, and loops are similarly huge (whatever length train you need to turn). The idea of fitting that kind of provision at every point where you might need to reverse a train is absolutely mad (and with terminus stations, you would need to have a way to drive trains in reverse safely, either in or out of the station). The costs and difficulties that removing cabs from one end of multiple units would be many, many orders of magnitude higher than the cost of including a cab at each end. Why do we even entertain such ridiculous ideas?

You'd never convert the existing system to that kind of operation, but balloon loops aren't uncommon on tramways - through stations are faster to run through than termini and you can avoid conflicts as trains arrive and depart. (I'd still have a cab on either end as the flexibility to reverse anywhere with a crossover is probably worth having).

What would Euston HS2 look like if it were on a balloon loop from OOC? the dwells there would probably still need to be long enough to demand a lot of platforms, but you might get away with less than the 11 that the full scheme demanded.

 

[Russel]

What problem is this trying to solve?

 

[Brightonboy]

Hello @andy33gmail -
The "field of clear vision" offered through a forward-facing window, is still far superior to looking at a monitor-screen.

- The screen gives less ease at spotting the tiny things in the distance (such as person trackside, vehicle on a crossing).
- Even 120-150Hz, a screen has an inherent eye-fatiguing screen flicker.
- What fail-over / fail-safe, for a loss of comms or hardware? Even a momentary loss of vision, is a safety-risk (i.e. missed signal).

I would assume that it would be like 'big boy' military drone operations such as Reaper and Protector with multiple screens all switchable for zoom and breadth of view - a drone operator has around 6 (but that includes the electronic 'dashboard' as well as the exterior views. Couple such a system with things like ETCS for semi-autonomous operations in some areas and it is technically feasible but the investment in comms and technology to operate safely and successfully in a crowded network would be enormous and probably the cost/benefit analysis probably wouldn't stack up.

 

[andy33gmail]

What problem is this trying to solve?

Potentially frees up a small amount of space. Crumple zone point noted, but you could use it for suitcases, bins, toilets, doors and get more seats elsewhere

It also changes the trade-off with gangway door vs full width cab - if you're typically only joining 2 MUs, you can use full width cabs but also have (wide) gangway. Although I appreciate that has issues in terms of making sure the right trains face the right way.

 

[Sun Chariot]

Potentially frees up a small amount of space. Crumple zone point noted, but you could use it for suitcases, bins, toilets, doors and get more seats elsewhere

So:
- conversion of infrastructure and vehicles, costs running into hundreds of billions?
- obsolescence of UK terminii, if a virtual cab can't internally-rotate 180 degrees?
- critical safety-cases of eye-fatigue and of reduced sighting (monitor vs window)?
- Industry resistance at the increased risk to passengers?
All for gaining 2 to 3 metres each end?
Seriously?

 

[Russel]

Potentially frees up a small amount of space. Crumple zone point noted, but you could use it for suitcases, bins, toilets, doors and get more seats elsewhere

It also changes the trade-off with gangway door vs full width cab - if you're typically only joining 2 MUs, you can use full width cabs but also have (wide) gangway. Although I appreciate that has issues in terms of making sure the right trains face the right way.

You'd be gaining one row of seats at most, is it really worth it?

 

[skyhigh]

It also changes the trade-off with gangway door vs full width cab - if you're typically only joining 2 MUs, you can use full width cabs but also have (wide) gangway.

Have a look at units such as the Danish Class MF, which have a full width cab at both end yet also have a wide gangway.

 

[Nottingham59]

a very good system of cameras and screens, to allow safe, reliable and ergonomic operation?

It ought to be possible for train to set back a short distance without the driver having to change ends.

If all freight trains had that capability, it would save a fortune in the design and construction of flyovers at places like Newark Crossing, where the approach gradients could be built at 1:50 or even steeper.

If it was guaranteed that a freight train that had stopped at the foot of the 1:50 slope, for whatever reason, could back up and get a run up the hill, then it doesn't matter how steep the climb is to get over the ECML, provided the vertical curvature was within limits.

 

[Yew]

- conversion of infrastructure and vehicles, costs running into hundreds of billions?

I don't think that the OP was suggesting converting existing trains.

 

[zwk500]

It ought to be possible for train to set back a short distance without the driver having to change ends.

If all freight trains had that capability, it would save a fortune in the design and construction of flyovers at places like Newark Crossing, where the approach gradients could be built at 1:50 or even steeper.

If it was guaranteed that a freight train that had stopped at the foot of the 1:50 slope, for whatever reason, could back up and get a run up the hill, then it doesn't matter how steep the climb is to get over the ECML, provided the vertical curvature was within limits.

That change to method of operations would require a lot more changes than just a rear-view camera. It would require signalling areas to be configured for the wrong-road (shunt) moves, and associated impact. It doesn't address the fundamental laws of physics of 'very heavy thing on very steep ramp with relatively little grip', and it would also need all the wagons in the train to be fitted with the appropriate cabling, or the loco to be able to talk to an End-of-Train Device.

The easier solution to exceptional gradients is to provide a loop sufficiently far back for the loco to get up to speed if it requires to be held, and issue an operating instruction that the train is to be given a clean run up the grade.

Where cameras would have value is things like runrounds, attaching locos and propelling moves into yards and sidings. Runrounds wouldn't even need a separate device, and I believe the 93s have cameras installed for this very purpose. Propelling moves would need an EOTD to be developed that had a suitable data link to the cab, and a system that wouldn't get confused if there were multiple compatible locos or EOTDs. I'd personally support the industry development of such an EOTD as part of train-borne integrity proving (the EOTD being connected to the brake line), as part of moving towards ETCS L2/L3 hybrid (although AIUI L3 no longer officially exists).

 

[Harpo]

If it was guaranteed that a freight train that had stopped at the foot of the 1:50 slope, for whatever reason, could back up and get a run up the hill, then it doesn't matter how steep the climb is to get over the ECML, provided the vertical curvature was within limits.

Unless something has changed, allowing ‘clear road conditions’ for freight is rare.

Maximum tonnages are usually based on the ability to restart a train from any point on an incline because there are numerous scenarios that might stop a train before, during or after an incline.

And that was before the days when an assist loco could be many hours away.

 

[Nottingham59]

Maximum tonnages are usually based on the ability to restart a train from any point on an incline because there are numerous scenarios that might stop a train before, during or after an incline.

Yes, of course. That's why the abilty to reverse a freight train to be able to take a run up a short but steep gradient is a pre-requisite for building a shorter and therefore cheaper ECML flyover at Newark Crossing. A train going at 10mph has enough energy to climb 1 metre. At 30mph, it can coast up 9 metres of elevation, no matter how steep the gradient, without any adhesion.

But I agree with @zwk500 that the ability to make driver-only propelling moves from the front cab would be even more useful.

 

[TastyMaltesers]

If you're thinking along the lines of getting rid of cabs, you may as well get rid of all the cabs and make the trains fully automated. Which won't happen for a very, very long time...

 

[Nottingham59]

If you're thinking along the lines of getting rid of cabs, you may as well get rid of all the cabs and make the trains fully automated. Which won't happen for a very, very long time...

If Waymo robotaxis can operate without a driver, then so can trains. (As is already done for the Pilbara iron ore trains in Australia)

But I agree, it's unlikely to happen in this country for a long time, for reasons that are social, not technological. Driverless busses are likely to come before driverless trains.

 

[spyinthesky]

If you're thinking along the lines of getting rid of cabs, you may as well get rid of all the cabs and make the trains fully automated. Which won't happen for a very, very long time...

The automation is quite simple but not on the current infrastructure or rolling stock.
Indeed a long way off but I imagine we will see more things like Luton Dart that have separate infrastructure.

 

[zwk500]

A train going at 10mph has enough energy to climb 1 metre. At 30mph, it can coast up 9 metres of elevation, no matter how steep the gradient, without any adhesion.

Surely this equation is dependent on the trailing mass?

Either way, backing up to charge a bank would have far-reaching impacts on operational safety that would require extensive changes to Operating procedures, rules, and the signalling systems to facilitate. Whereas you can manage a 1:50 gradient without backing up by simply not putting a signal too close to the foot of the bank.

 

[Transilien]

If we really need the space, couldn’t drivers cabs be open to passengers like BR did on the PEP/MK3 stock?

 

[MarkyT]

Surely this equation is dependent on the trailing mass?

Either way, backing up to charge a bank would have far-reaching impacts on operational safety that would require extensive changes to Operating procedures, rules, and the signalling systems to facilitate. Whereas you can manage a 1:50 gradient without backing up by simply not putting a signal too close to the foot of the bank.

As at Dainton Bank in Devon. On the down, after the 2-aspect R/G signal near the former site of Aller Junction, about half a mile before the steep gradient begins in earnest, the next stop signal is at the portal of Dainton Tunnel, at the brow of the hill. When HSTs were allowed to run beyond Newton Abbot with only one power car operative, signallers were instructed to give them a clear road from the platform, and scheduled stops at Totnes were withdrawn.

Note that for a short ramp associated with a flyover for example, only a proportion of a long freight will be on a ramp at any instant. For a 800m train on a 200m ramp, only a quarter of the tonnage requires extra force for lifting.

 

[andy33gmail]

I don't think that the OP was suggesting converting existing trains.

Indeed, I was hypothesising about what could be done with future stock. Clearly it would be a mad amount of modification just to free up the driver’s seat as a passenger seat

If you're thinking along the lines of getting rid of cabs, you may as well get rid of all the cabs and make the trains fully automated. Which won't happen for a very, very long time...

Clearly there’s a benefit to having at least one human around who’s qualified to deal with emergencies properly (“all lines are blocked, the train is on fire, run” vs “please remain seated, a train is coming on the other line”)