Freight Train queries (tail lights and maximum train length)

[jonathan01n]

I live in Lincoln and quite often walk pass those two level crossing. I am quite interested looking at the freight trains. The freight trains in there generally operated by a 60 or a 66. I noticed at the end of the last wagon(or tankers) there is a red lamp with white background attached at the left side of the wagon or tanker. I thought it is used to notify the train behind but it didnt make sense as the train is protected by signal already and if it is use for that purpose then other passenger trains should have it too but passenger trains there dont have this thing.

Also I want to ask why those freight trains there never hauled more than 32 tanks, I counted them and the maximum wagons there never exceed 32 tanks.

Thank you in advance
Jonathan:roll:

 

[GB]

The lamp you refer to is called a tail lamp. It marks the rear of the train and confirms the train is complete. Passenger trains tend to have built in tail lights as the formation is pretty static. Freight trains get shunted about a lot so the lamp needs to be removable.

Each route is subject to a maximum load and a maximum length a train can be, this as well as terminal capacity usually limits the number of wagons hauled.

 

[brtom]

To add to the above, the rail light was important when Absolute Block Signalling was used as the signaller used it to confirm the train hadn't come apart (and left wagons blocking the track)

 

[Rover]

Each class of loco has a maximum load for each route (as GB states) this is dependent on gradients. On a route with lesser gradients a loco will be able to haul a greater tonnage than on one with severe gradients.

To give an example. When I was in Nottingham Control we would occasionally have to send 36 loaded HAA MGR's from Toton to Worksop for West Burton or Cottam power stations. The direct route would have been over Kirkby summit via Shirebrook but the gradient was too steep for a class 56 or 58, a class 60 was OK or 2x 56s/58s in multiple.

With only a single 56/58 it would need to go via Chesterfield to Worksop and reverse as by this route the gradients were lesser. If we sent it over Kirkby we would need to knock it down to (from memory) 30 or maybe it was 28.

So the 32 wagons would either be the maximum tonnage permitted for that loco on that route and/or the maximum length for that route.

 

[jopsuk]

To add to the above, the rail light was important when Absolute Block Signalling was used as the signaller used it to confirm the train hadn't come apart (and left wagons blocking the track)

"when". There's still parts of the network with Absolute Block and no train detection system

 

[TheEdge]

"when". There's still parts of the network with Absolute Block and no train detection system

Even then the true reason for a tail lamp is still mostly academic these days. In the days of absolute block and unfitted freights (to the OP, thats a train where some or all of the wagons have no brakes) it obviously was possible for a train to divide, the drive be none the wiser and the first time anyone notices is when the train passes the next signal box minus tail lamp, assuming the guard hadn't reached another box first.

Today while AB still exists most (if not all) trains in the UK have continuous brakes and will stop automatically if they divide. Although it does on occasion lead to bizarre moments, during a signal failure my driver was asked if the train was "complete with tail lamp", we were in a 153!

 

[jonathan01n]

Even then the true reason for a tail lamp is still mostly academic these days. In the days of absolute block and unfitted freights (to the OP, thats a train where some or all of the wagons have no brakes) it obviously was possible for a train to divide, the drive be none the wiser and the first time anyone notices is when the train passes the next signal box minus tail lamp, assuming the guard hadn't reached another box first.

Today while AB still exists most (if not all) trains in the UK have continuous brakes and will stop automatically if they divide. Although it does on occasion lead to bizarre moments, during a signal failure my driver was asked if the train was "complete with tail lamp", we were in a 153!

Maybe it is coupled with another 153, or 156, 158, 150, 170, on that day ?
Dont forget pacer!

 

[Domh245]

Even then the true reason for a tail lamp is still mostly academic these days. In the days of absolute block and unfitted freights (to the OP, thats a train where some or all of the wagons have no brakes) it obviously was possible for a train to divide, the drive be none the wiser and the first time anyone notices is when the train passes the next signal box minus tail lamp, assuming the guard hadn't reached another box first.

Today while AB still exists most (if not all) trains in the UK have continuous brakes and will stop automatically if they divide. Although it does on occasion lead to bizarre moments, during a signal failure my driver was asked if the train was "complete with tail lamp", we were in a 153!

Given the problems that some 153s are facing structurally, I can see why he might ask! :P

 

[Tomnick]

Even then the true reason for a tail lamp is still mostly academic these days. In the days of absolute block and unfitted freights (to the OP, thats a train where some or all of the wagons have no brakes) it obviously was possible for a train to divide, the drive be none the wiser and the first time anyone notices is when the train passes the next signal box minus tail lamp, assuming the guard hadn't reached another box first.

Today while AB still exists most (if not all) trains in the UK have continuous brakes and will stop automatically if they divide. Although it does on occasion lead to bizarre moments, during a signal failure my driver was asked if the train was "complete with tail lamp", we were in a 153!

It's still possible though, albeit very unlikely. A continuously braked freight train might have some sort of blockage in the brake pipe, for example (enough at least to allow the loco to maintain a brake on the front portion). It could be as simple as the cocks left closed when wagons were last attached. Similarly, I understand that there were a few examples of 15x units becoming 'fully' uncoupled in service in their earlier days, with the rear portion stopping but the front portion carrying on unchecked - again unlikely, but not impossible with a false feed or something to the wrong place?

 

[jopsuk]

I guess the other factor these days with hanging a lamp on the rear of the train- or with multiple units, checking that it is lit- is that it helps ensure that the full length of the train has been inspected.

 

[daikilo]

Another reason why trains may have limitted length is the length of signalling sections (particularly around junctions) and/or of passing loops. In this case it won't be X wagons + loco/s but a total length of Y meters.

 

[John Webb]

Even then the true reason for a tail lamp is still mostly academic these days. In the days of absolute block and unfitted freights (to the OP, thats a train where some or all of the wagons have no brakes) it obviously was possible for a train to divide, the drive be none the wiser and the first time anyone notices is when the train passes the next signal box minus tail lamp, assuming the guard hadn't reached another box first.

Today while AB still exists most (if not all) trains in the UK have continuous brakes and will stop automatically if they divide. Although it does on occasion lead to bizarre moments, during a signal failure my driver was asked if the train was "complete with tail lamp", we were in a 153!

Unfitted freight wagons also used 3-link couplings, these could at times break if the train moved off too quickly, so they always had a guards/brake van carrying the tail lamp at the rear of the train. Hopefully (but not always) if the train did split the guard could control/stop the rear part of the train safely.

Modern goods trains use modern couplings far less prone to allow a train to split and have the continuous brake fitted, hence brake vans are not needed and the tail lamp is placed on the last wagon instead. You will note that modern passenger units have twin built-in tail lamps - this is a further safety factor so if one lamp fails there is still a tail lamp showing. Tail lamps still have a role to play in stations where 'Permissive Working' is allowed (ie to let one train approach another particularly if they are to be coupled together) or as an extra safeguard in signal failure conditions when trains have to be 'talked past' one or more signals that are not working.

 

[Sunset route]

Another reason why trains may have limitted length is the length of signalling sections (particularly around junctions) and/or of passing loops. In this case it won't be X wagons + loco/s but a total length of Y meters.

If that was a real issue then our morning peak timetable wouldn't run as most of our suburban and outer suburban trains are longer than the signal sections around a certain multiple junction complex just north of Croydon, where it's not unheard of for three trains to be back blocking over junctions in the rear while waiting a forth to clear. Freights are often passed through as swiftly as possible for obvious reasons.

 

[najaB]

Freights are often passed through as swiftly as possible for obverse reasons.

Are those similar to interior motives?

 

[Sunset route]

Are those similar to interior motives?

lol auto correct at its worst and now corrected thanks.