Longest permitted freight train

[Zontar]

I know this is quite vague and many variables, but what's roughly the longest freight train that can run on the UK network?

 

[Mcr Warrior]

Fair question! Is it effectively restricted by the maximum length of the various passing loops on the network?

 

[swt_passenger]

Fair question! Is it effectively restricted by the maximum length of passing loops on the network?

The enhancement project a few years ago that was known as “strategic freight network” improvements was to increase various loop lengths for container trains up to 775m.

Although presumably you can have longer trains if they don’t need looping, and there’s room somewhere off the mainline to assemble them?

The high output track renewal and ballast cleaning trains are about the same length as the longest container trains, IIRC.

 

[Merle Haggard]

Autos. and liner trains used to be 100 - 102 s.l.u.* but I understand that Southampton 'liners can take 106 now. I think 106 is the longest on the network
The 102 vs 100 relaxation was because length limits were exclusive of brake van, so the logic was used - well there is allowance for a brake van, could be one at each end and there aren't any, so we'll use that extra.

Oddity was that West Midlands - Harwich P.Q. automotive trains were 100 s.l.u., but there were few or no loops on the G.E. that were that length. It took a while for our operating colleagues to realise, meanwhile the trains always had a good run

Most freight weights out** before it lengths out, automotive and containers are the exceptions.

*s.l.u. - single length unit.
**Weight out means train reach max trailing load before length limit, length out obvs reverse.

 

[JeffH16]

Autos. and liner trains used to be 100 - 102 s.l.u.* but I understand that Southampton 'liners can take 106 now. I think 106 is the longest on the network
The 102 vs 100 relaxation was because length limits were exclusive of brake van, so the logic was used - well there is allowance for a brake van, could be one at each end and there aren't any, so we'll use that extra.

Oddity was that West Midlands - Harwich P.Q. automotive trains were 100 s.l.u., but there were few or no loops on the G.E. that were that length. It took a while for our operating colleagues to realise, meanwhile the trains always had a good run

Most freight weights out** before it lengths out, automotive and containers are the exceptions.

*s.l.u. - single length unit.
**Weight out means train reach max trailing load before length limit, length out obvs reverse.

The Mendip Quarry Traffic runs to around 107SLU, and 4500T trailing

 

[Mcr Warrior]

*s.l.u. - single length unit.

Thanks for the explanation. So, how long is an 's.l.u.'? Something like 21 feet / 7 yards? (Which would make a 100+ s.l.u. length goods train almost half a mile long!)

 

[Merle Haggard]

The Mendip Quarry Traffic runs to around 107SLU, and 4500T trailing

Thanks, interesting; in my days with the Construction sector, we never had to worry about length limits! Shows how freight diesel locos. have improved in drawbar pull.
Just interesting how it's been creeping up from 102 (about 30 years ago), very slowly.

Thanks for the explanation. So, how long is an 's.l.u.'? Something like 21 feet / 7 yards? (Which would make a 100+ s.l.u. length goods train almost half a mile long!)

I think so - as I think you've guessed, it was based on 9' or 10' wheelbase wagons which where pretty universal when the book came out, easy to calculate a train length in s.l.u. then, you just counted the wagons!

 

[norbitonflyer]

In theory there is no maximum, but the second longest train on any single track line must be capable of fitting in a loop so that the longest one can pass it. (I think the Alcan trains on the West Highland Line are longer than some of the passing loops)

Not a freight train, but a couple of years ago the Rhaetian railway ran a train of 100 cars (over a mile long)

Train with 100 carriages sets new record for longest passenger train

The Rhaetian Railway company has set the record for the world's longest passenger train with a 1.9-kilometre-long train, while on a journey through the Alps.

www.bbc.co.uk

 

[Harpo]

Is the high output ballast cleaning train still about?

 

[dk1]

Is the high output ballast cleaning train still about?

Lots of special instructions when that noisy smelly thing was about.

 

[Merle Haggard]

In theory there is no maximum, but the second longest train on any single track line must be capable of fitting in a loop so that the longest one can pass it. (I think the Alcan trains on the West Highland Line are longer than some of the passing loops)

Two points; lengths are also limited by signalling, one issue being if, when standing at a signal, the rear end still hasn't reached the previous signal. Blocks other routes and, more likely, level crossings.

The rule that one train (of two) must be shorter than a loop when passing was overlooked by signallers in the very early days of Railtrack; 102 slu cars trains, one empty and one loaded, were signalled from Coventry and Leamington respectively towards each other, with the expectation of crossing at the intermediate loop at Kenilworth. Which wasn't long enough. It did raise issues in the New World of the railways.

 

[childwallblues]

6X41 and 6X43 Dagenham to Garston cars and their return workings must be some of the longest on the network.

 

[Snow1964]

Two points; lengths are also limited by signalling, one issue being if, when standing at a signal, the rear end still hasn't reached the previous signal. Blocks other routes and, more likely, level crossings.

Although not used by freight trains, a lot of busy approaches to South London stations and Liverpool Street etc had signals about every 310m.

It was based on 12car x20m and about 4 carriage lengths of empty space, plus small margin. So trains could be close if previous one was waiting at a signal. These spacings were too low where line speed was above something like 55mph (forgotten speed now, but it was based on a W braking curve)

 

[Falcon1200]

The rule that one train (of two) must be shorter than a loop when passing was overlooked by signallers in the very early days of Railtrack; 102 slu cars trains, one empty and one loaded, were signalled from Coventry and Leamington respectively towards each other, with the expectation of crossing at the intermediate loop at Kenilworth. Which wasn't long enough.

Two overlength trains can cross at a loop on a single line, although it is a convoluted and time-consuming process, and not recommended!

The length limit, IIRC, on the northern WCML is 71 SLUs, so that trains can fit in the loops, however certain intermodal trains are authorised to run at around 100 SLUs. Which does work, as long as the overlength train, and all the other trains sharing the route, are on time......

 

[Taunton]

The Mendip Quarry Traffic runs to around 107SLU, and 4500T trailing

I do sometimes notice, westbound on the GWML, returning empty stone trains with loco, a consist, then another loco and another full consist. I've never been able to see whether the second loco is under power, or manned. Presumably the overall tonnage is less than a single loaded train in the opposite direction, and it saves on paths, but it must be difficult to loop out of the way on the Berks & Hants.

Most freight weights out** before it lengths out, automotive and containers are the exceptions.

*s.l.u. - single length unit.
**Weight out means train reach max trailing load before length limit, length out obvs reverse.

Same concept in air freight for filling cargo aircraft. Expressions are "Gross Out", meaning the aircraft reaches its maximum gross takeoff weight before it is completely filled, and "Bulk Out", meaning all compartments are full but you have not reached gross weight limit.

 

[Wilts Wanderer]

Two overlength trains can cross at a loop on a single line, although it is a convoluted and time-consuming process, and not recommended!

I was just thinking about this, presumably it involves splitting one of the trains and using the second one to shunt the rear portion back into the loop once the front part has pulled forward? That would be a nightmare to coordinate with modern rules etc, you’d probably still be filling the paperwork out the next day

 

[Harpo]

In some places, overlength trains need special instructions for passing loops. Do NSTR loops still need both tokens to be held until complete with tail lamp inside the loop and the token in rear given up, and for a responsible person (e.g. a MOM) to be on site to be the holder of them?

 

[Taunton]

I was just thinking about this, presumably it involves splitting one of the trains and using the second one to shunt the rear portion back into the loop once the front part has pulled forward? That would be a nightmare to coordinate with modern rules etc, you’d probably still be filling the paperwork out the next day

More common occurrence in the USA, where it is known as "sawing past". Yes, with UK rules it would take for ever. US crews can be experts at it, just done with radio messages.

 

[Harpo]

The Mendip Quarry Traffic runs to around 107SLU, and 4500T trailing

The jumbo train a couple of decades ago was 59+ 50x102 tonne wagons max, 5225 (?) tonnes gross. It also had (quite rare) special signalling instructions for clear road conditions when diverted up Dauntsey.

 

[ExRes]

6X41 and 6X43 Dagenham to Garston cars and their return workings must be some of the longest on the network.

If I remember correctly when I was 66 brake handling in the very late 90s the Corby car train was 2600ft, slightly different to my everyday mail trains

 

[norbitonflyer]

Two points; lengths are also limited by signalling, one issue being if, when standing at a signal, the rear end still hasn't reached the previous signal. Blocks other routes and, more likely, level crossings.

Back in Victorian times, the GNR concept of a "steam tender" (basically a second set of cylinders and motion under the tender, fed from the locomtive boiler, making an 0-6-0+0-6-0) to allow longer coal trains to operate with one crew, foundered on the fact that in the event of a breakdown such a long train could block all three level crossings in Lincoln (then, as now, the usual route for freight trains), cutting communicatiuon between the north and south of the city (there were no bridges across the railway until 100 years later)

 

[Merle Haggard]

If I remember correctly when I was 66 brake handling in the very late 90s the Corby car train was 2600ft, slightly different to my everyday mail trains

Indeed - th P.S.A. (Peugeot etc) from 4 French factories combined & then through the Tunnel to the new car terminal at Corby, conveyed in C.T. WIA wagons. Started with the registration peak traffic, promised to be all year round. One morning waiting for my London train at Wellingborough I was on the (then open) footbridge and it made a very impressive sight snaking round the curves from Irchester.

Corby auto terminal and WIA wagons now just seem to be a memory. E.W.S.

 

[Railsigns]

*s.l.u. - single length unit.

Standard Length Unit.

 

[66701GBRF]

6X41 and 6X43 Dagenham to Garston cars and their return workings must be some of the longest on the network.

Length limit is 121 SLU and regularly run 115+

 

[ExRes]

One morning waiting for my London train at Wellingborough I was on the (then open) footbridge

It wasn't you that lobbed a brick at my windscreen was it? MML Turbo up road

 

[Nottingham59]

Thanks for the explanation. So, how long is an 's.l.u.'? Something like 21 feet / 7 yards? (Which would make a 100+ s.l.u. length goods train almost half a mile long!)

Google tells me that an SLU is exactly 21 feet, i.e. 6.401m

 

[Dunfanaghy Rd]

Length limits used to exclude the loco. Train lists &c. were in feet. Unannounced overnight 10-11 Feb 2007 feet became metres and length limits jumped by 3 slu to include locos. I was at Fratton during the Pompey Resignalling on the Sunday night. Even the TOPS clerk at Donny hadn't known about it.
By 2017, when I retired, 4O39 Morris Cowley to So'ton East Docks was 108 slu. Imagine the fun and games when it was diverted via Guildford and Havant one day.
Pat

 

[Merle Haggard]

Length limits used to exclude the loco. Train lists &c. were in feet. Unannounced overnight 10-11 Feb 2007 feet became metres and length limits jumped by 3 slu to include locos. I was at Fratton during the Pompey Resignalling on the Sunday night. Even the TOPS clerk at Donny hadn't known about it.
By 2017, when I retired, 4O39 Morris Cowley to So'ton East Docks was 108 slu. Imagine the fun and games when it was diverted via Guildford and Havant one day.
Pat

Of topic, but illogical in my opinion - the length limit did not include loco or brake van (which are obviously part of the length, intrinsic in the case of the loco.) but load limits, as originally designed, did include the weight of the loco. Because adding an assistant loco (if of identical power) only increased total train load by 50% if the locos concerned were heavy and puny (a speciality of N.B.L. . ) adding an assisting loco didn't increase the trailing load very much.

The train you mentioned was run by M.A.T. in the past. I gained a first-hand experience of the means by which that company always ensured its needs were paramount regardless of convention and I'll leave it at that ...

 

[LRV3004]

6X41 and 6X43 Dagenham to Garston cars and their return workings must be some of the longest on the network.

I used to shunt those at Garston - they were 120SLU at their maximum length, about half a mile long!

 

[Merle Haggard]

I used to shunt those at Garston - they were 120SLU at their maximum length, about half a mile long!

They used two-way secure radios there, in the old 100 s.l.u. days, riding on the Cartic at the front of the propelling move, did go badly wrong once

There was also a very entrepreneurial autos supervisor then.