Steam v Diesel

The drawback of a DMU is the more inflexible capacity of a 1/2/3 car DMU set than a 5/6 coach Mark 1 set. Plus they are less likely to have something like on train catering on board to milk a little additional secondary spend out of the passengers (depending on the length of the line that may or may not be necessary). Plus, as I believe has been commented on the Bluebell thread at one point, the cost of overhauling a carriage with doors for every set of seats is greater than that of overhauling a coach with just 6 doors spread across the carriage. Are you saving money on the cost of running a DMU but then having to spend more when it comes to overhauling it because of the added difficulty and cost of having more doors to repair?

 

I think "whole train cost" is an important consideration, rather than just motive power cost. In other words, seat-for-seat, is it cheaper to run (once you take into account all overhauls and maintenance costs) say, a three car DMU or a loco + 3 coaches. Which then gets further complicated since when things are busy, the loco can haul 6 coaches; and it can also rescue a failed train; whereas the 3-car DMU is - well, a 3-car DMU. So there's a question about how much do you consider is worth paying for that flexibility.

Another thought on carriage costs in a mixed traction set up is that essentially in most cases I suspect a DMU represents additional carriages, rather than replacement carriages - in which case it is additional maintenance cost. In other words, if you are currently managing with a maximum requirement for 2 * 6 coach sets at peak times, but trains only need to be three coaches off peak, it may still be cheaper overall to have a loco (whether steam or diesel) that is over powered for the off-peak period pulling a three coach train than to introduce an additional DMU which is at face value cheaper to operate than a large diesel + 3 coaches, but only if the maintenance cost of the DMU isn't additional.

Which is not to come down on any particular side of the argument, but simply to note that there are a lot of subtleties to consider. Financially I suspect you want to run the smallest possible fleet that nonetheless enables you to run a sustainable service - though your heritage objectives may conflict with that and push you to having more operational stock than you need because of the intrinsic heritage value of the additional stock.

Tom

 

Most DMU's can run in multiple, so if one has a fleet of say two 2-car sets and maybe a 3-car set then 2, 3, 4, 5 or 7 coach trains can be run on demand easily. Pretty flexible.

I agree with your point on door maintenance 100%, but it is inaccurate to suggest DMU's in general have lots of doors. Only around 40% of preserved first generation DMU's are of the suburban door configuration, the rest are low density with typically 4 to 6 passenger doors per vehicle, much like a standard MK1.


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I did get a quote from a friend of mine regarding the ‘top end’ overhaul of the power unit of the machine that we and several of our friends were involved with, and it was rather cheap compared to some of the figures I’ve seen bandied about, I will say the loco involved was always treated as a bit of a hobby type of thing, if there was say 10 days use out of it, it was considered a good year.
Its current owner seems to be making rather good use of it atm.

 

The income side of the issue does not seem to be getting much discussion. If your prime revenue stream is a steam hauled dining service then diesels at peak times will not attract the numbers or justify the higher price. At the EVR we run dining trains, fish and chips excursions and afternoon teas, sometimes all three in one day, and it is the steam haulage plus added the value of the catering to the experience which brings visitors in to us.

 

Based off that. Swaange Railway Return would be £170 for Steam and £40 for the class 33. The difference being only 6.5 Adults.

In other words... IF, IF everything else was the same. The pure 'cost' of having an extra steam service would be offset by it getting another 7 adults on each return service.... something I personaly would expect would be very easy to do.

 

There has been little discussion about diesel fuel costs. I have no direct experience but I am reliably told that the fuel cost for a 3 car DMU (which will move 160 + passengers - how may times do our loads really exceed that figure?) is a fraction of that for a larger mainline size diesel loco per mile. The power units of DMUs appear to far less complex and bespoke compared to a mainline diesel loco. No surprise then that BR turned to DMUs when costs were under scrutiny. As with running over size steam locos there appears to be a certain amount of unwarranted vanity over the provision of some diesel power.

 

The fact they are running a diesel suggest the offset may well be higher.

 

I think a lot depends on your diesel of choice. For a long while we had an six coupled industrial diesel with a Gardner driving through a 4 speed air change gearbox (which made it much more fun to drive that most diesels) as our passenger diesel loco. It isn't very fast (it is only 205bhp), but it does a five mile round trip including a chunk of 1 in 35 with 2 mk1s on a single gallon of diesel.

For a notional low season day, 4 round trips you are talking diesel consumption of around £15-20 a day. But that's Gardner power, which is well known to be superior to just about anything else; we also have a supercharged Roll-Royce powered Barclay that makes about 350bhp, and that would cheerfully drink £15 worth of diesel idling between trains, never mind when you actually made it do something (strangely enough we've never bothered fit it with vac brakes).

We pay a flat £50 a day hire on the diesels, £250 on the steam locos.

If we steamed our most economical steam loco (four coupled 12"), and it had been out the day before and so was warm, we would get away with a little bit less than 1/2 ton of coal (£250) over 4 trains. If we had to use a bigger loco (say an Austerity) and perhaps hadn't got the best crew out, then consumption could be more like a ton (£500).

The diesel only needed the side rods and horns oiling (roller bearings on the axles), so another £20-30 saved on oil compared to a steam loco.

So all in, for a low season day, the diesel is under £100, and the steam loco at best is pushing £500.
That's 32 passengers a day at our current price of £12.50 a head, or 8 per train.

Interestingly, the reality is that we currently are an all steam service for various reasons, but not least because all but one of our vac fitted diesels are stopped for repairs, and the remaining diesel loco whilst fighting fit is a very historic diesel mechanical with a top speed of 6 mph, which makes a 5 mile round trip feel rather a long way. Meanwhile we've four steam locos of varying size in ticket (although one is out on hire), so our usage is driven more by the realities of loco availability than anything else.

 

But then, if you start running a train with 4, 5, or 7 engines working (1 per carriage), is that not less efficient than having a 4, 5, or 7 coach train pulled by a smaller diesel like a 20 or 25? I feel like I've heard that once you get to that kind of level the fuel cost of running a DMU can jump above that of a small Bo-Bo diesel

 

I've heard various figures, and would want someone to advise. On the big railway, Chiltern reckon that their cl. 68+Mk3 sets compare well economically with DMUs once at 6 carriages.

All of this brings in the questions of overhaul and maintenance, though.

 

I am involved in running a small fleet of 101 DMU's on the GCR and 2 of the original power cars we bought straight of service have now been withdraw due to needing there tyres turned after 20 years service .
the 4 units we originally bought had all been converted in to sandite vehicles and had spent several years after being withdraw from passenger services spreading sticky sand around the network, so as you can imagine
they had not come in for a lot of care and attention, and its amazing to me that we as a small group have managed to keep them running safely for 20 years with limited resources and personnel.
But now unforchanatly we are going to have to spend ,to us, serious moneys getting them working again we are at the moment negotiating to have the complete bogies sent away and the wheels reprofiled,
which for one pair of bogies is going to cost approx. £5,000 so to get the 2 units back in to traffic we are going to have to find £10,000.
we have been lucky as a group as we have managed to obtain a couple of spare gear boxes and a spare engine which we have had refurbished but again the engine rebuild cost well over £2000
as time goes on the amount of spares available will become less and more expensive to overhaul.
we do have another power car which although has not run in preservation we had hoped to one day restore but it seems likely now that it will become a source of spares to keep the rest of the fleet running.
So although the moneys involved in keeping the 101 fleet running is small beer compared to a steam loco, it is a lot harder to rase funding and donations from the general public to keep the fleet running and of cause
the milage fee that we claim from the railway doesn't cover the maintenance costs.

Colin

 

Didn't Eastleigh have DMU spares left over when the Swanage DMUs were refurbished and some were scrapped?

I see the Lion diesel loco team at the MHR managed to raise £13k by "crowdfunding" for a repair on the generator, so
https://www.national-preservation.com/threads/50027-main-gen-repair-fund.1421606/

 

This is correct. If railways ran their diesel fleets on a purely fuel efficient basis then you would continue using DMU's until you had 300 people to shift. At this point, a Class 20 is doing better than a big chain of DMU's in multiple with lots of powercars in the consist.

Thing is.... If you are lucky enough to have 300 people interested in visiting your railway on a particular service you are probably running steam at this point anyway. It's quite rare to have huge numbers of people happy to ride the non-steam offering. Most diesel running is done at quieter times or as a supplement service bolstering an existing steam diagram. In both these cases, DMU wins over diesel loco. If Heritage lines were in the business of moving heavy freight and long distance main line running, the debate would pan out very differently.

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