Large and Small locomotive economics, ex-West Somerset Railway developments

On a line like the WSR, coal and water capacity are important considerations and tender engines hold more of both. It isn't really practical to take coal part way along the line, and even to have to do it every round trip is a potential timetable headache.

 

Indeed - which just goes to show that there is far more to selecting suitable motive power - even amongst the subset of engines that actually exist - than just finding the smallest possible loco that can shift the load.

Tom

 

The motive power debate seems to have sparked some interest.
Practically I think there are a lot of factors to take account of, once this is done then the choice of motive power seems quite straightforward.

1) Section length. Look at the current summer diagram and you'll see it's pretty hard to squeeze in more trains that fit in with the needs of the passengers. It's easy to forget most of them are on holiday so running much before 10.00 am is going to be a waste. Note also what this does to run round times available! Nobody wants to rush a shunt just to put on or take off a coach during the day.
2) Gradient profile. There are two climbs both from standing starts whichever direction you are going.
3) Water capacity. Small tank engines are marginal on a round trip. We always take water after 20 miles with tank engines and more often than not we've used just over half the capacity at that point. There is no water or coal at Williton (except for emergency water).
4) Passenger enjoyment. As has been mentioned people don't want to be squashed in. I have seen people standing in peak season even with 7 or 8 coach trains.
5) Locomotive availability. You don't always have a choice or at least as much choice as you'd like.

Basically I have faith in the Op's team and the CME to run the right length trains with the right motive power whenever they can within the constraints of the operating schedule. I do appreciate it's not like it was in branch line days but that's why we have galas to a certain extent to cater for the enthusiast market.

 

Sadly that doesn't matter. We're all 'militant gricers' so reality checks like that don't count!!

 

The WSR's CME Andy Forster has been following the coal consumption debate and offers this information:

"WSR records the coal loaded onto each loco daily throughout the year and the miles worked for each loco, from this an average coal consumption per mile can be obtained. Here are the results for 2011 when all the regulars plus 5553 and 34046 were operational.

9351 76.1 lbs per mile
88 78.5
3850 78.2
4160 71.9
5553 69.2
7828 79.5
34046 92.6

These figures include the coal taken to light up and steam tests following washouts etc, WSR trains generally have a station stop every 2 miles which explains the relatively high consumption compared with test figures in BR days. 75 lbs per mile equates to 2.05 tonnes to do an 'average' 60 mile day. High mileage days will use less per mile but other days such as steam experience and Santa days (21 miles) will use more per mile and put the average up."

Steve

 

Err, IIRC almost every engine that went to Barry came out again (although for some it took many years)? ISTR there were a handful chopped up, but just a very few; and of course the Barry 10 were left at the end (and even a few of those are now under restoration - of the ones that didn't become parts donors). Now, of the ones that came out, not all have been restored and are now running, but again IIRC the majority have.

Noel

 

How true that is. There's more economy to be gained from a good driver & fireman v an indifferent crew. As well as a better looked after engine. This was well known in BR days & even earlier.
Very sad to hear about David Holmes. Had a few good trips with him in my time as a fireman

 

Thanks Steve - these figures are very interesting.

With the vagaries of doing a long study with presumably varying loads and different crews etc, there are several interesting points:

- To all intents and purposes, there is no difference between the large-prairie-alike 9351, a Manor, a GWR 2-8-0 and and S&DJR 2-8-0.
- There is also essentially no difference between a small prairie and a large prairie. Are these locos generally used on lighter trains? It is interesting that there is a bit of difference between 4160 and 9351.
- Relative to coal consumption in GWR / BR days, on a heritage line with short daily duties the amount used in lighting up is a disproportionate amount of the total (for example, you use the same lighting up and leave the same on the grate at the end of the day whether the daily duty is 60 miles or 240 miles, but on the short duty, the amount that contributes to the coal per mile is effectively four times higher). I assume that accounts for the higher coal consumption of 34046, which with a large grate will take more to light up. Even so, the difference in coal consumption between, say, 88 and 34046 (which presumably see similar duties, i.e. train weights) is only 18%.

Tom

 

From an earlier post in the WSR Developments thread.

 

IIRC the as yet unrestored 5668 (now on the K&ESR) also carries a GW No 2 boiler of late build or modification with super heater the same as 4160.

 

That 18% though would add up over time and represents an extra £40/day in round figs for coal alone to run a Bulleid rather than say the Manor or 2884 class (the latter certainly being capable of hauling a much heavier load at line speed than the 4-6-2 should the occasion require that).

 

Indeed. Though interestingly, it puts a figure on the "gricer premium" - if running a Bulleid was sufficient to draw in 2 - 3 extra passengers per day, it would be worth it

There is a whole other side to the debate which hasn't really been aired, which is the mileage between heavy overhauls.

People often talk about "ten yearly" overhauls as if they were a single monolithic thing, but really there is a boiler cycle (where you get annual insurance that may, all being well, continue for ten years). And then there is a mechanical side to things that is mileage based. In an ideal world, you would try to adjust the annual mileage so that the target mileage between overhauls took about ten years to run.

In practice, that means different mileages for different locos. Going on pre-grouping, grouping and BR figures, a typical pre-grouping loco will probably run 40 - 50,000 miles between overhauls. A typical grouping-era loco might run 70-80,000 miles. A BR Standard or similar modern loco might run about 100,000 miles or so. Realistically, that means you probably shouldn't expect more than 4-5k miles per year out of a pre-grouping loco; about 7-8k miles from a grouping loco; perhaps 10k miles or more from a BR Standard or rebuilt Bulleid. In other words, a small pre-grouping loco may be cheaper to run in coal, but you will need twice as many of them to run a given service. If I were a Locomotive Superintendent and had freedom to make the choice, I'd trade coal consumption for high reliability and a big mileage between overhauls, since it would mean the works throughput could be lower.

Tom

 

Tom, I tend to agree with what you say. If I had my choice I would run a 76xxx, 75xxx,80xxx, and 2x S15. Ideally I would then have a black 5 or an S15 or both as "overhaul" spares. Not that this looks remotely like any railways fleet of course! Personally I wouldn't bother with the Bulleids, but I appreciate that this is a personal prejudice. The rebuilts are a decent loco though.

What hasn't been mention but are factors:
1. What the money is available for....people giving money for 35005 don't necessarily support 30828 though arguably the latter is more useful, if it is a choice between having a loco and not then clearly it is better to have the MN.
2. We have volunteers who want to work on specific locos, and we have a situation where in order to keep people interested and engaged we have more locos under overhaul than a strictly rational approach might allow. (By we in this context I mean heritage railways in general).

 

So if a BR Standard runs 100,000 it will need to do 10,000 a year so on a 10 mile line with 2 round trips a day it will need to run approx 250 days a year so most likely every operating day. On a 20 mile line doing 1 1/2 round trips will need to run approx 160 days so about 2/3 of the operating days. If the line works on steam weekends only they will never get any where near that mileage.

 

I guess the other issue to consider is what the hire rate / other costs to the railway is. To take an example of the Bulleid pacifics in use or under overhaul, I guess not that many are assets of the host railway operating company. Some (most?) have been or are being restored because their owners want it that way and are prepared to pay for it (and then find somewhere to run it at a rate which suits the hirer), and for one or two possibly the railway may be under an obligation to restore it as part of a previous usage deal etc, so any disadvantage in theoretical direct economics (and which are arguably within a margin of possible variables based on crew/ coal quality / loco condition / inefficient usage) may be only part of the total economic picture. I expect you could go to the Bluebell or the GCR or the Severn Valley, to take a few random examples (the NYMR seems less profligate), point to each loco on the premises and ask what is that doing here ( i.e. why are you keeping it now), and the answer is probably going to be different for most of the locos.

Having said that, heritage railways do things which don't seem to make economic sense but hopefully (for their sake) only occasionally.