Loco-Hauling vs Multiple Units for InterCity Operations.

[Bletchleyite]

Also true of units being over-specified, the power ratings of some are ridiculous, why do 185s need 2250hp for example? Fuel consumption must be quite serious for a 3 car unit?

It's so they can maintain linespeed over the hills. But yes, they do drink fuel.

 

[XAM2175]

It’s interesting to see the new OBB nightjet stock is fixed formation sets which is quite a new concept for overnight sets. I don’t think they are having spare vehicles to swap in and out but I stand to be corrected!

The Italians either have stopped, or intend to stop, allowing loco run-arounds at their terminal stations, so in that case the primary need is to have a cab at both ends of each train. The fixed formation aspect is secondary to that.

 

[TT-ONR-NRN]

The Italians either have stopped, or intend to stop, allowing loco run-arounds at their terminal stations, so in that case the primary need is to have a cab at both ends of each train. The fixed formation aspect is secondary to that.

Good, far more flexibility with that.

 

[inais20]

Ah, the Nova 3 debacle. Only procured because "LCHS" would be easy and quick to get into service rather than any actual operational advantage (which promptly backfired)

Sorry if it’s a noddy question (I don’t generally follow what’s happening in TPE land) but what exactly backfired with their LCHS stock?

 

[zwk500]

Sorry if it’s a noddy question (I don’t generally follow what’s happening in TPE land) but what exactly backfired with their LCHS stock?

It took a very long time to get it into service, thereby negating the entire point of ordering LHCS instead of additional MUs.

 

[87015]

The Italians either have stopped, or intend to stop, allowing loco run-arounds at their terminal stations, so in that case the primary need is to have a cab at both ends of each train. The fixed formation aspect is secondary to that.

They haven’t had anything run round in absolutely donkeys though have they? Sounds a lot like an excuse that means nothing. Engine changes can be done in far less time than a reversal, tour i did today quite happily propelled into Milan C…

 

[Krokodil]

It solves the problem of turnaround time but the trade-off is that push-pull are fixed formations which makes them less flexible than "proper" loco-hauled units.

The Mk5 sets were specified as fixed formation sets, but that doesn't mean that push-pull inherently means no flexibility. I've watched SBB strengthen trains by adding a few coaches coupled to a driving car in front of the existing driving car.

On the contrary - with loco haulage, if you add more carriages you need a bigger loco - but with a multiple unit, the extra power comes with the extra carriages.

Which adds to the cost after a while. Five or so small engines cost more to run and maintain than one big engine.

Has anyone ever thought of having a diesel locomotive that can feed power to thge motors of an electric train, thus giving the advantages of distributed power without having to take the loco itself over the electrified section of the route?

It's one thing to have permanent traction buses from vehicle to vehicle (though that used to be discouraged) but I can imagine that relying on jumper cables for those sorts of voltages and currents would bring the ORR out in a cold sweat.

 

[mpthomson]

Also true of units being over-specified, the power ratings of some are ridiculous, why do 185s need 2250hp for example? Fuel consumption must be quite serious for a 3 car unit?

They were specifically designed for the Trans Pennine routes that have some quite stiff and/or long gradients so that timings could be maintained more easily.

 

[Richard Scott]

They were specifically designed for the Trans Pennine routes that have some quite stiff and/or long gradients so that timings could be maintained more easily.

If that's the case do they have capability of shutting one or more engine(s) down when less power is required?

 

[43066]

If that's the case do they have capability of shutting one or more engine(s) down when less power is required?

They do but it generally isn’t used in practice AIUI.

 

[Trainbike46]

They haven’t had anything run round in absolutely donkeys though have they? Sounds a lot like an excuse that means nothing. Engine changes can be done in far less time than a reversal, tour i did today quite happily propelled into Milan C…

nighjet sleepers currently run the locomotives around. This is why the new nightjet stock (which has a DVT) will go to Italy first

 

[Energy]

Personally I think the HST had a good idea by using two locos. Benefits of loco hauled, with less disadvantages.

The HSTs are more because they need two diesel engines to have enough power. For the IC225s they switched back to a electric loco + DVT.

 

[zwk500]

The HSTs are more because they need two diesel engines to have enough power. For the IC225s they switched back to a electric loco + DVT.

Interestingly, the HSTs began life being counted as DMUs - Classes 253, 254 and 255. The Power Cars + Trailers idea has of course also been taken up by Alstom for their TGV family.

 

[D365]

Personally I think the HST had a good idea by using two locos. Benefits of loco hauled, with less disadvantages.

Now that most of our 125mph routes have been electrified, there’s very little need for diesel haulage at speeds above 100mph.

 

[12LDA28C]

As explained above, this potentially robs capacity because you lose platform space by having to accommodate the loco and DVT (if push-pull) which do not carry passengers.

Unless you used a DBSO which of course has passenger accommodation, although less capacity than a standard trailer.

 

[Andrew*Debbie]

Now that most of our 125mph routes have been electrified, there’s very little need for diesel haulage at speeds above 100mph.

Crewe to Holyhead should be an exception.
The Welsh government has asperations of Holyhead to Chester and Llandudno to Crewe in 60 minutes.

https://www.gov.wales/sites/default/files/publications/2020-07/north-wales-main-line-rail-network-map.pdf

 

[Trainbike46]

Unless you used a DBSO which of course has passenger accommodation, although less capacity than a standard trailer.

but of couse, the end cars of an MU typically also have less capacity than a middle car

 

[HamworthyGoods]

Unless you used a DBSO which of course has passenger accommodation, although less capacity than a standard trailer.

No need to use a DBSO as you don’t have to have the brake there. Just a plain Driving Standard Trailer will do.

 

[coppercapped]

On the contrary - with loco haulage, if you add more carriages you need a bigger loco - but with a multiple unit, the extra power comes with the extra carriages.


Swings and roundabouts - the longer the electric segment of the journey, the greater the advantage of adding a diesel engine at the limit of electrification instead of bringing it with you. (Similar argument for carrying current collection gear, especially transformers, over non-electrified track, although the weight penalty is less so the balance point will be different).

Has anyone ever thought of having a diesel locomotive that can feed power to thge motors of an electric train, thus giving the advantages of distributed power without having to take the loco itself over the electrified section of the route?

Er, yes. Nearly 100 years ago in 1929...

...the Buenos Aires Great Southern Railway, built two 1,200hp mobile power houses which hauled five coaches, three 1st & two 2nd class providing total seating for 554. The CME of BAGSR, Mr P C Saccaggio, was reluctant to initiate full electrification of the lines around Buenos Aires due to the cost, but believed in the idea of powered coaching stock drawing power from a diesel electric generator set installed in a 'mobile power house'.

For more details see the DerbySulzers.com website at https://derbysulzers.com/argentinadmu1935.html

And until the Foster Review of the Intercity Express Programme in 2010 the IEP was essentially exactly the same thing: a string of coaches with motors sandwiched between two pantograph/transformer cars for the electric sets; between two diesel-electric generator cars for the diesel version and between one pantograph and one diesel car for the electro-diesel (or bi-mode) version.

 

[D365]

Crewe to Holyhead should be an exception.
The Welsh government has asperations of Holyhead to Chester and Llandudno to Crewe in 60 minutes.

Class 805 will only be capable of ~100mph on diesel.

 

[Bletchleyite]

Class 805 will only be capable of ~100mph on diesel.

Why? Is it lower powered than other 80x?

 

[SuperLuke2334]

Why? Is it lower powered than other 80x?

Believe its only got the 740hp engines

 

[D365]

Why? Is it lower powered than other 80x?

I understand it’s only the Class 810s that are specified for 125mph on diesel.

 

[AndrewE]

The HSTs are more because they need two diesel engines to have enough power. For the IC225s they switched back to a electric loco + DVT.

BR found with the APT that the train polished the rails, hence putting the power cars in the middle for maximum adhesion, when they had first been planned to be at one end. Otherwise they would have been faster in one direction than the other.
HSTs must have benefitted from half the power being supplied at the back and with the benefits of a claean rail.

 

[87015]

nighjet sleepers currently run the locomotives around. This is why the new nightjet stock (which has a DVT) will go to Italy first

Which one? Venice and Milan don’t even have the option to run round despite what Twitter might tell you

 

[O L Leigh]

Unless you used a DBSO which of course has passenger accommodation, although less capacity than a standard trailer.

That helps, but only a bit. You’ll still have the loco to accommodate.

 

[Shaw S Hunter]

They do but it generally isn’t used in practice AIUI.

If this is actually true when did things change? An important feature of the 185 design is the availability of Eco-Mode allowing the 3-car unit to run with just 2 engines running. Plenty of TPE routes where use of Eco-Mode was standard SOP. I'd be genuinely surprised if Eco-Mode has been ditched.

 

[43066]

If this is actually true when did things change? An important feature of the 185 design is the availability of Eco-Mode allowing the 3-car unit to run with just 2 engines running. Plenty of TPE routes where use of Eco-Mode was standard SOP. I'd be genuinely surprised if Eco-Mode has been ditched.

I don’t know for sure (hence “AIUI”), it’s something I seem to remember being discussed on here some time ago.

 

[Master29]

I would be inclined to agree. There are few arguments against EMUs, but DMUs have the noise issue, though some modern ones like 80x insulate it quite well.

To be honest that`s one of the areas they are quite good.

 

[Andrew*Debbie]

Class 805 will only be capable of ~100mph on diesel.

Yes, unfortunatly. As far as I know, the current linespeed is 90mph or less. Most of Anglesey is 75 with 40 or 45 between Llanfairpwll and Bangor.

That is why I said should in italics. A Class 805 won't be able manage Holyhead to Chester in 60 minutes. According to railmiles it is 84 miles 31 chains.

The fastest train today, stopping only at Bangor and Llandudno Junction, does the run in 1h 27m. That is with a class 67 hauling four mk4 coaches.