Long Trains and speed restrictions

[Newshound Mutt]

For example, if somebody was driving an 11 car 390 or a massive freight train with lots of waggons, when going over say a TSR, how do they know their tailend has passed through it before speeding up again? On a tram, they have rear view cameras so they know when the back has passed over the restriction. With a long train, how does the driver judge this with no rear end camera?

 

[HamworthyGoods]

For example, if somebody was driving an 11 car 390 or a massive freight train with lots of waggons, when going over say a TSR, how do they know their tailend has passed through it before speeding up again? On a tram, they have rear view cameras so they know when the back has passed over the restriction. With a long train, how does the driver judge this with no rear end camera?

It’s part of the drivers route knowledge in signing the route, no difference to knowing the braking distances so the train is at the correct speed before reaching a TSR.

 

[a340egkk]

Some locos, for example 66s, have a system whereby the train length is programmed in, and the driver can press a button when passing a T board or the commencement of a higher PSR, which will then sound an alert when the full train length has passed the point. I'm not sure whether it's always 100% reliable, especially if the programmed train length is wrong, but it's an aid.

 

[Nym]

Train Length is part of the QTron DataCord 6100 OTMR units, as is a lot of other non-OTMR functions. Hence, other locomotives fitted with the same OTMR share this function, off hand I beleive this includes the Class 57/0, 60 and I think 67.

 

[snowball]

On lines where the signalling goes over to ETCS, the system will need to know the length of each train somehow?? How will that be done?

 

[irish_rail]

For example, if somebody was driving an 11 car 390 or a massive freight train with lots of waggons, when going over say a TSR, how do they know their tailend has passed through it before speeding up again? On a tram, they have rear view cameras so they know when the back has passed over the restriction. With a long train, how does the driver judge this with no rear end camera?

On IETs, there are rear view cameras which come in handy when driving a 10 car through a 20mph TSR!
Also, on ATP fitted lines the ATP tells you when the whole train has passed through the affected track .

 

[SteelWeelApeal]

On an HST I’ve seen the driver stick his head out of the door and look back down the train to see if the rear power car had finished a 20mph curve.

 

[driver9000]

Guesswork up to a point on trains without countdown or cameras that work on the move. You know how long your train so you can roughly judge how long it takes for the tail to pass the T board.

 

[GB]

It’s part of the drivers route knowledge in signing the route, no difference to knowing the braking distances so the train is at the correct speed before reaching a TSR.

Clearing a TSR is not part of a drivers route knowledge. As others have said freight locos tend to have a countdown feature otherwise failing that it is best guess.

 

[Roast Veg]

On lines where the signalling goes over to ETCS, the system will need to know the length of each train somehow?? How will that be done?

This is something of an open problem, but the suggestion was that an ETCS "box" will be required every six carriages/wagons, with the "box" responsible for those units only. Through wiring for communication and power is not something the freight operating companies really want, so if there's a way around this, then I'm sure we will see it.

 

[John Webb]

This is something of an open problem, but the suggestion was that an ETCS "box" will be required every six carriages/wagons, with the "box" responsible for those units only. Through wiring for communication and power is not something the freight operating companies really want, so if there's a way around this, then I'm sure we will see it.

Tail lamp with GPS and radio connection at the end of the train, perhaps?

 

[Roast Veg]

Tail lamp with GPS and radio connection at the end of the train, perhaps?

Possibly! As per the Moorgate/ECML resignalling thread R&D appears to be ongoing, but I'm sure that a preferred choice has been reached at an architectural level already.

 

[XAM2175]

On lines where the signalling goes over to ETCS, the system will need to know the length of each train somehow?? How will that be done?

This is something of an open problem, but the suggestion was that an ETCS "box" will be required every six carriages/wagons, with the "box" responsible for those units only. Through wiring for communication and power is not something the freight operating companies really want, so if there's a way around this, then I'm sure we will see it.

Tail lamp with GPS and radio connection at the end of the train, perhaps?

Onboard train-integrity detection is only required to implement ETCS Level 3, which is the moving-block level. ETCS Level 1 (overlay on conventional signalling) and Level 2 (in-cab signalling with fixed blocks, as used on the Cambrian and what the ECML will be getting) both continue to rely on track-based train detection with track circuits and axle counters and the like.

 

[John Webb]

Onboard train-integrity detection is only required to implement ETCS Level 3, which is the moving-block level. ETCS Level 1 (overlay on conventional signalling) and Level 2 (in-cab signalling with fixed blocks, as used on the Cambrian and what the ECML will be getting) both continue to rely on track-based train detection with track circuits and axle counters and the like.

Thanks for the clarification.

 

[JN114]

ETCS Level 1 (overlay on conventional signalling) and Level 2 (in-cab signalling with fixed blocks, as used on the Cambrian and what the ECML will be getting) both continue to rely on track-based train detection with track circuits and axle counters and the like.

That’s not the correct definitions for Level 1 and Level 2

Level 1 has system-to-train communication via “active” balises - movement authorities can only be received as the train passes over balises. In Level 1 all the balises have to be powered and wired into the signalling system to receive movement authorities to pass onto the train.

Level 2 has system-to-train communication via GSM-R - movement authorities can be received and updated at any time. Balises are only provided to give position updates to trains; and are unwired - they behave like contactless bank cards and take their power from the reader on the train.

Either can be an overlay on a conventional signalling or a standalone system with just block markers.

All 3 currently live systems in the UK - Cambrian, Thameslink Core and Heathrow/GWML Inner are Level 2. The latter 2 are overlaid on conventional signalling.

In Level 2, ETCS knows the length of the train because you input it when setting up the train - the “Start of Mission” process involves inputting Train ID, current location similar to how it’s done on the GSM-R radio; it will then ask the driver about train characteristics and offer the driver a series of buttons with different lengths available for that traction - on the Heathrow 387s that’s just 4/8/12/16 car. With freight or similar I expect it’ll be more involved, but essentially the same idea.

It needs to know the train length to give the driver the correct acceleration point after a speed restriction.

 

[XAM2175]

That’s not the correct definitions for Level 1 and Level 2

I had simplified it for the purposes of whether or not they required onboard integrity detection, but thanks for the additional information regardless.

 

[Roast Veg]

In Level 2, ETCS knows the length of the train because you input it when setting up the train - the “Start of Mission” process involves inputting Train ID, current location similar to how it’s done on the GSM-R radio; it will then ask the driver about train characteristics and offer the driver a series of buttons with different lengths available for that traction - on the Heathrow 387s that’s just 4/8/12/16 car. With freight or similar I expect it’ll be more involved, but essentially the same idea.

It needs to know the train length to give the driver the correct acceleration point after a speed restriction.

Ah, my mistake. A little knowledge is a dangerous thing.

 

[Railperf]

What do you have on 745/755 @dk1 ?

 

[Shwam3]

What do you have on 745/755 @dk1 ?

745s & 755s have a train length measurement activated by double-tapping the DSD pedal.
If you're asking about ETCS, they have no equipment at all (except the backup speedo on the TCMS which looks like the ETCS one).

 

[dk1]

What do you have on 745/755 @dk1 ?

No ETCS yet but as said, double clicking the DSD tells us when clear.

 

[brad465]

Sometimes, especially I think where only a handful of class types use a specific line, there are additional boards to say when a particular train length has cleared the T board. I remember on the SEML between Folkestone and Dover there was an example of this years ago, with additional signs for all the formation possibilities that 375s and 395s make, which are pretty much the only regular trains to use that particular stretch.

 

[DaveTM]

There are three ways that I use, knowing what a 4/8/12 car train looks like on the other line of a double track, imagining what a train would look like on the other line of the double track, and mental arithmetic.

For PSRs on a reasonably busy double track, one day you will approach the PSR at the same time that a train is coming in the other direction. When the front of that train reaches a point opposite the speed board, the back of the train is where you can start accelerating if your train is the same length. Forevermore I will take power from the leaning blackthorn tree at Arundel Junction when I'm in a 4 car unit...

Until then I imagine a train to compare against and add a bit for safety. This loses a tiny bit of time, but see below...

The third method requires a little quick maths, based on the fact that 45 miles per hour is 20.12 meters per second (i.e. one coach length per second). For instance, we recently had a 20mph ESR on a piece of fairly featureless line. 20mph is a little worse than half of 45mph so just over 2 seconds per carriage. Driving a 12 car that multiplies to 24 seconds. To cover my arse I count to something more like 36 and then go. (1) The passengers are safe, (2) even if the managers are out with a speed gun my licence is safe, and (3) I have lost less than 12 seconds more than I needed to (which I'm not going to get a please explain for given that slowing for the 20 and running through it has probably lost more than 2 minutes anyway).

Think though of the effect of a 5mph ESR on a 12 car train. One second per carriage at 45mph equates to 9 seconds per carriage at 5mph. A 12 car through a 5mph loses 108 seconds even if you don't consider the decelleration and acceleration times. It's no wonder track defects requiring 5mph ESRs get fixed before they have time to be published in the Late Notice Case!

 

[dk1]

I must admit that I have memorised most locations when I am in clear. I rarely use the ‘double click’ on Stadlers as there are enough sounds in the cab without the bloody annoying BLEEP BLEEP too.