Loco & coach combination - why so rare?

[davsarg]

Hi,

As the title suggests really. The traditional image of a locomotive hauling a rake of coaches on regular timetabled services is now becoming an increasingly rare sight on the network. Does anyone know why this is?

Thanks.

 

[HSTEd]

Cost too much.
Multiple units are superior in almost every way.

 

[Greenback]

Money and technology. Units are cheaper to operate and technology has allowed pricing to be used to fill empty seats, thus allowing fixed formations to be more effective.

 

[NSEFAN]

Locomotives and carriages are seen as old fashioned practice. They require additional stock movements to operate (run-rounds, etc) which also requires extra infrastructure (loops, shunt signals, etc). They also tend to have poorer acceleration due to all the traction power focused in one place, rather than distributed along the train.

 

[yorkie]

Hi,

As the title suggests really. The traditional image of a locomotive hauling a rake of coaches on regular timetabled services is now becoming an increasingly rare sight on the network. Does anyone know why this is?

Thanks.

For train lengths of 5 or less coaches, it's more economical to use units. Today the drive is towards shorter, more frequent services.

However there are some routes where passenger numbers have soared to the extent that loco haulage would now be viable.

Also, with few exceptions, these days you need a vehicle with a cab at the other end, such as Driving Van Trailer (DVT) or Driving Brake Standard Open (DBSO), as it's often either impossible or impractical to run locos around.

 

[PHILIPE]

Another cause of overcrowding. For every 4 coach loco hauled, 2 coach DMUs replaced or something similar.

 

[dgl]

And also that a multiple unit has more passenger space for it's length and so allows longer trains on some platforms

 

[Yew]

And also that a multiple unit has more passenger space for it's length and so allows longer trains on some platforms

Depends on the length, lots of MU's have equipment cabinets at either end of the coach, which eat into the space available, this can quickly add up to close to the length of a locomotive. Although modern MU's are getting better for this.

 

[RichmondCommu]

Money and technology. Units are cheaper to operate and technology has allowed pricing to be used to fill empty seats, thus allowing fixed formations to be more effective.

However you could argue that units are less likely to be fixed than loco hauled stock given that we no longer have station pilots to carry out shunting. With units you can quickly add or indeed remove at stations and depots according to demand. With trains formed of carriages you are effectively stuck with that formation for the entire day.

 

[Bletchleyite]

However you could argue that units are less likely to be fixed than loco hauled stock given that we no longer have station pilots to carry out shunting. With units you can quickly add or indeed remove at stations and depots according to demand. With trains formed of carriages you are effectively stuck with that formation for the entire day.

Notably DB and SBB treat hauled stock *as* manually coupled units - bang a complete set on the end including driving trailer and sometimes even locomotive.

(SBB are very much moving towards units, though, as are DB, though it does surprise me that SBB are using long units for IC rather than 4-cars to give some flexibility, and no inter-unit gangways either)

 

[PHILIPE]

However you could argue that units are less likely to be fixed than loco hauled stock given that we no longer have station pilots to carry out shunting. With units you can quickly add or indeed remove at stations and depots according to demand. With trains formed of carriages you are effectively stuck with that formation for the entire day.

Difficulty to add according to all demand - There aren't any !!!

 

[HSTEd]

There is a picture somewhere of a pair of Railjets joined end to end in service. Complete with locomotives.

 

[RichmondCommu]

Depends on the length, lots of MU's have equipment cabinets at either end of the coach, which eat into the space available, this can quickly add up to close to the length of a locomotive. Although modern MU's are getting better for this.

I would argue that is a bit far fetched. A Pendolino loses nothing like the amount of space to equipment that a class 90 or class 87 plus DVT did. The same goes for the Meridians that have replaced HST's on the MML.

 

[najaB]

I would argue that is a bit far fetched. A Pendolino loses nothing like the amount of space to equipment that a class 90 or class 87 plus DVT did. The same goes for the Meridians that have replaced HST's on the MML.

To be fair though, DVT's could have had some passenger accommodation if the rules allowed it at the time they were developed.

 

[MCR247]

There is a picture somewhere of a pair of Railjets joined end to end in service. Complete with locomotives.

Which is a complete waste of space in terms of platforms

 

[30907]

But platform length at major stations is rarely an issue in Austria Switzerland or Germany. Or France with TGV power cars.

 

[jopsuk]

Pretty sure RailJet "units" including a locomotive coupling together is a common procedure, often with one loco in the middle (both is perfectly possible)

 

[Yew]

I would argue that is a bit far fetched. A Pendolino loses nothing like the amount of space to equipment that a class 90 or class 87 plus DVT did. The same goes for the Meridians that have replaced HST's on the MML.

I said locomotive, not a Locomotive and DVT, If we assume any new LHCS wouldnt have a DVT, but seats in the driving car, like most modern high speed MU's (so no passangers in the front 1/3 of the car)
However at the other end, if we take an 11 coach pendolino, that should have approximately 20 cabinets for equipment, lets assume they're 0.5m each, gives us 10m of space. Adding in a third to this gives 15m. which isnt too far from the length of a HST power car. remembering that the HST power car has some space in the back for parcels/bikes, suddenly LHCS doesnt look so wasteful, especially when the fact that in some places the loco can hang off the platform is taken into account.

the main issues are track wear (locomotives are heavy), acceleration due to a low number of powered axles, and redundancy from only having a single engine, instead of many.

 

[RichmondCommu]

Difficulty to add according to all demand - There aren't any !!!

With the exception of special events trains in the South East tend to be shorter during the off-peak / weekends than they are during the week.
--- old post above --- --- new post below ---

I said locomotive, not a Locomotive and DVT, If we assume any new LHCS wouldnt have a DVT, but seats in the driving car, like most modern high speed MU's (so no passangers in the front 1/3 of the car)
However at the other end, if we take an 11 coach pendolino, that should have approximately 20 cabinets for equipment, lets assume they're 0.5m each, gives us 10m of space. Adding in a third to this gives 15m. which isnt too far from the length of a HST power car. remembering that the HST power car has some space in the back for parcels/bikes, suddenly LHCS doesnt look so wasteful, especially when the fact that in some places the loco can hang off the platform is taken into account.

You seem to be forgetting that a HST has two power cars. How often are bikes stored in a HST? I've never seen that happen on the MML or ECML and for what its worth parcels have not been carried on service trains for many years.

 

[jopsuk]

There's an enduring myth that adding/removing coaches based on immediate demand was ever a widespread, common, practice.

 

[RichmondCommu]

Pretty sure RailJet "units" including a locomotive coupling together is a common procedure, often with one loco in the middle (both is perfectly possible)

Fair play to yourself and HSTEd I wasn't aware of that I presume that both locos power the train?
--- old post above --- --- new post below ---

There's an enduring myth that adding/removing coaches based on immediate demand was ever a widespread, common, practice.

Having seen it for myself in the late 1970's it certainly wasn't a myth although everything would have been pre planned according to the timetable . Hence the reason why station pilots were employed.

 

[notadriver]

To be fair though, DVT's could have had some passenger accommodation if the rules allowed it at the time they were developed.

If that were the case newer stock would be of the loco hauled push/pull type but the many advantages of multiple unit type trains outweigh the disadvantages.

 

[HSTEd]

The Southern seems to have abandoned non unit trains even before the war. (Rakes of coaches were numbered and used as units for example).

 

[RichmondCommu]

The Southern seems to have abandoned non unit trains even before the war. (Rakes of coaches were numbered and used as units for example).

With exception being services that ran down to the South West and would have been strengthened at weekends. This might have been the case for services to Bournemouth too.

 

[Dent]

However there are some routes where passenger numbers have soared to the extent that loco haulage would now be viable

I'm not sure how soaring passenger numbers cause loco haulage to become viable.

Hauled sets have less passenger space for the train length, and using vehicles with poorer acceleration would mean that fewer paths could be fitted into the timetable. Both these things mean that hauled sets become less viable the higher the passenger demand.

 

[CosherB]

Has anyone mentioned 442s yet?

 

[najaB]

I'm not sure how soaring passenger numbers cause loco haulage to become viable.

Adding additional carriages is cheaper than additional units.

 

[Bletchleyite]

Adding additional carriages is cheaper than additional units.

But then you lose acceleration.

 

[najaB]

But then you lose acceleration.

The delta depends on how over/under powered the loco is. But agreed that with multiple units adding vehicles will have a lesser impact.

 

[dubscottie]

The big reason I would say is track maintenance costs.. Not just run round loops but the damage that locos do to bridges etc..

The Almond Valley Viaduct on the Edinburgh - Glasgow QS line is a good example..

It was (and prob still is) falling down after years of Class 27's and 47's hammering over it at close to 90mph an average every 15 mins, 6 days a week..

Locos and coaches could work but only if there is spares at each end of a journey. (and the leasing costs were on a pay per mile basis)

The Cross Country trains of the 80's till 1991 were a good example. Plenty of spare early Mk2's tagged onto the regular sets when demand was high.

Thats when you got NSE coaches in Edinburgh and ScotRail ones in Penzance!