DMU railcars VS Loco hauled trains

Run_to_da_hills

Whats the advantages and disadvantages of each?

It seems to be a trend here, in the UK and across europe towards using railcars instead of loco hauled trains.

I could see some obvious advantages such as quicker accelleration with under floor motors, the fact that a train can continue its journey with one or several of its power units down.

On the down side DMU are noisier than "motorless" carriages, they also look as if they would be nasty to work on, ie tight underfloor space compared to a loco where everything is larger and accessible.

Journey for journey which is more economical, several smaller under carriage motors or one large header with a DVT?

Cookie_Monster

there are stil a lot of electric loco hauled services in Europe.

Loco advantage:
flexible single unit
more powerful engine
only one engine less to go wrong

DMU advantage:
multiple engines so more flexible if one fails
no running round required - faster turnaround, less infrastructure required
better fuel consumption (in theory)
lower axle loading

Wikipedia wrote:

Benefits

A train composed of DMU cars scales well as it allows extra passenger capacity to be added at the same time as motive power. It also permits passenger capacity to be matched to demand, and for trains to be split and joined en-route. It is not necessary to match the power available to the size and weight of the train - each unit is capable of moving itself, so as units are added, the power available to move the train increases by the necessary amount.

Distribution of the propulsion among the cars also results in a system that is less vulnerable to single-point-of-failure outages. Many classes of DMU are capable of operating with faulty units still in the consist. Because of the self contained nature of diesel engines, there is no need to run overhead electric lines or electrified track, which can result in lower system construction costs.

These advantages often outweigh the underfloor noise and vibration that may be a problem with this type of train.

KC61

Run_to_da_hills wrote: »

Whats the advantages and disadvantages of each?

It seems to be a trend here, in the UK and across europe towards using railcars instead of loco hauled trains.

I could see some obvious advantages such as quicker accelleration with under floor motors, the fact that a train can continue its journey with one or several of its power units down.

On the down side DMU are noisier than "motorless" carriages, they also look as if they would be nasty to work on, ie tight underfloor space compared to a loco where everything is larger and accessible.

Journey for journey which is more economical, several smaller under carriage motors or one large header with a DVT?

Well staff cost reductions are one significant element - with DMU rather than loco hauled you do not require a guard and you do not require shunters at either end of the journey to uncouple and recouple the locomotive.

The internal noise element on the 22K sets it has to be said is pretty minimal.

Trampas

KC61 wrote: »

The internal noise element on the 22K sets it has to be said is pretty minimal.

Quiet as a mouse compared to the 28000

foggy_lad

railcars are more economical when only 1 2 or 3 cars are needed
DMU units more comfortable ride than jerky loco hauled trains

JHMEG

Getting rid of locos also means getting rid of the ability to do freight.

Trampas wrote:

Quiet as a mouse compared to the 28000

28000 = how not to design a form of transport

Run_to_da_hills

JHMEG wrote: »

Getting rid of locos also means getting rid of the ability to do freight.

And also carry a decent number of bicycles and diminishes the possibility of reintroducing Fasttrack again.

KC61

JHMEG wrote: »

28000 = how not to design a form of transport

I'd agree that the 2800 DMUs are a pretty basic train but they are also one of the most reliable with probably the lowest failure rate of any train in these islands.

That has to be a good thing?

foggy_lad

Run_to_da_hills wrote: »

And also carry a decent number of bicycles and diminishes the possibility of reintroducing Fasttrack again.

irish rail dont really do freight though, they provide a service for tara mines and for a couple of factories in mayo that need transport direct to the port, there is no sugar beet and no cement anymore so a few locomotives can easily be kept for these services and fastrack will never be reintroduced! it was a failure for so long it would never repay what it has already lost taxpayers. and i am sure proper accommodation could be made on the new trains for a few extra bicycles!

JHMEG

KC61 wrote: »

I'd agree that the 2800 DMUs are a pretty basic train but they are also one of the most reliable with probably the lowest failure rate of any train in these islands.

That has to be a good thing?

Would you consider yourself a glass-half-full type of person?

Cookie_Monster

JHMEG wrote: »

28000 2800 = how not to design a form of transport

care to give some reasons for that?

As far as I can see they do exactly what they should, move large volumes of people. seat are comfortable. as stated previously they are very reliable too...

KC61

JHMEG wrote: »

Would you consider yourself a glass-half-full type of person?

The 2800s do exactly what they are built to do - they are a highly reliable commuter train.

While not ideal they filled the gap on the Rosslare route until the 22000 sets were deployed there.

However, the fact remains you rarely ever hear of them failing. That to me is what most people want from a commuter train?

JHMEG

Cookie_Monster wrote: »

care to give some reasons for that?

As far as I can see they do exactly what they should, move large volumes of people. seat are comfortable. as stated previously they are very reliable too...

My apologies for mixing them up. These are not as bad as the 2600s, which are:
Noisy.
Smokey.
Does the AC work, or is there just none?
Seats are NOT comfortable.
Noisy.

The seats are not comfortable on any Irish railcars except the 22000s. They are too narrow, too upright, and have too little padding.

The noise is excessive on any railcar that has a diesel engine under the floor in the passenger compartment.

Or maybe I just have higher standards/better expectations.

Run_to_da_hills

KC61 wrote: »

The 2800s do exactly what they are built to do - they are a highly reliable commuter train.

While not ideal they filled the gap on the Rosslare route until the 22000 sets were deployed there.

However, the fact remains you rarely ever hear of them failing. That to me is what most people want from a commuter train?

Jap reliability.

These look better with the pass through blocked off.

murphaph

DMUs are pretty rare in Germany tbh, usually only used for very lightly trafficked rural routes (2 car sets).

Under the wires, loco hauled push pull sets are very common on regional and IC services, as are EMUs on the newer ICEIII units (older ICE units were loco top and tail).

On commuter it's mostly EMU of course.

kingshankly

although 28s don't have as many features as the 29s thy are far more reliable and solidly built than their Spanish counterparts

Run_to_da_hills

kingshankly wrote: »

although 28s don't have as many features as the 29s thy are far more reliable and solidly built than their Spanish counterparts

I don't think Iarnrod Eireann will be buying from Spain again.

Trampas

Was on a 29000 today when the breaks gave up (sticking) between confey and clonsilla.

Some amount of smoke generated on it

corktina

the biggest plus point (if you can call it that I guess) of a fixed formation unit over loco and carriges is the simpler track and signalling needed at termini and the savings in staff and time from not having to run-round. DMUs and 201 plus Mk4 are in this category.

kingshankly

railcars main advantages are with individual engines if some fail you can still carry on. no runarounds, no guard needed,with computer screens an instant notification of any problem and where saves time faultfinding and is a cleaner environment.
disadvantages not as powerful, most not permitef to exceed 70, not as comfortable, and from a drivers perspective it's real train driving

Run_to_da_hills

kingshankly wrote: »

railcars main advantages are with individual engines if some fail you can still carry on. no runarounds, no guard needed,with computer screens an instant notification of any problem and where saves time faultfinding and is a cleaner environment.
disadvantages not as powerful, most not permitef to exceed 70, not as comfortable, and from a drivers perspective it's real train driving

Would dissagree with you on the comfort, I much prefere the 22000's over the Mark 4's

kingshankly

Run_to_da_hills wrote: »

Would dissagree with you on the comfort, I much prefere the 22000's over the Mark 4's

your correct they are but not as comfortable as de dietrict, I was generalising. IMO the mark 4s are a glorified railcar inside anyway

Run_to_da_hills

kingshankly wrote: »

your correct they are but not as comfortable as de dietrict, I was generalising. IMO the mark 4s are a glorified railcar inside anyway

They will probably end up as filler cars for DMU sets when the remaining 201's give up the ghost..:p

Few pet hates, I don't like seating that dose not line up correctly with the windows, and also the air vents that are up against the windows in the MK4's

highlydebased

kingshankly wrote: »

railcars main advantages are with individual engines if some fail you can still carry on. no runarounds, no guard needed,with computer screens an instant notification of any problem and where saves time faultfinding and is a cleaner environment.
disadvantages not as powerful, most not permitef to exceed 70, not as comfortable, and from a drivers perspective it's real train driving

Can have a diagnostics system present on a loco hauled train too- the MK4's has it.

foggy_lad

kingshankly wrote: »

your correct they are but not as comfortable as de dietrict, I was generalising. IMO the mark 4s are a glorified railcar inside anyway

no the 22000 are far more comfortable than anything else on rails in ireland except maybe

corktina

kingshankly wrote: »

your correct they are but not as comfortable as de dietrict, I was generalising. IMO the mark 4s are a glorified railcar inside anyway

in the context of this post, the Mk4s are a DMU.....just as the Uk HSTs are (thats about the only comparison though....HSTs have got to be the most sucessfull fleet ever....201+mk4s? not even a contender Im afriad..

JHMEG

foggy_lad wrote: »

no the 22000 are far more comfortable than anything else on rails in ireland except maybe

What is that? Is that what Frank Fahy has promised people they'll be getting on the WRC?

Rud

is that not the presidential coach?

Judgement Day

Rud wrote: »

is that not the presidential coach?

It's the old Great Southern & Western Railway Royal Saloon No.351 of 1902 - almost brand new now after being vandalised and latterly burnt by locals 'presumably' from the Inchicore area.

lord lucan

Judgement Day wrote: »

It's the old Great Southern & Western Railway Royal Saloon No.351 of 1902 - almost brand new now after being vandalised and latterly burnt by locals 'presumably' from the Inchicore area.

Currently on show in Utrecht in an exhibition of Royal/State carriages.:)

http://www.steamtrainsireland.com/carriages/carr351.htm

http://www.spoorwegmuseum.nl/en/actueel/royal_class.htm

Judgement Day

Nice the way there's no mention of the vandalism and arson attacks carried out under CIE's noses at Inchicore or about the carriage being saved by the intervention of the GSRPS in the first instance but I'm not going there now.

kc56

kingshankly wrote: »

railcars main advantages are with individual engines if some fail you can still carry on. no runarounds, no guard needed,with computer screens an instant notification of any problem and where saves time faultfinding and is a cleaner environment.
disadvantages not as powerful, most not permitef to exceed 70, not as comfortable, and from a drivers perspective it's real train driving

22000's are capable of 100mph and cruise comfortably at 90mph.

As for power, a 22K has a 450hp engine in each carragie; a 3-car has 1350 hp and a 6-car has 2700hp. A class 141 loco, which would have been used on short trains, is 1100hp,an 071 is 2240hp and 201 3200hp. So a typical 22k set is more powerful than equivalent loco hauled sets apart from the push-pulls with 201's. 22K's have better acceleration and much better braking, thanks to their dynamic retarders, than the Mk4-201 sets which relay on brake pads.

Red Alert

I traveled on a 22k just this weekend - they're perfectly comfortable and have very low engine noise. Never thought I'd say that about a railcar but there you go.

Run_to_da_hills

Red Alert wrote: »

I traveled on a 22k just this weekend - they're perfectly comfortable and have very low engine noise. Never thought I'd say that about a railcar but there you go.

Shisssh, 22K are not railcars,

Railcars only exist along the WRC.