the recent thread on consisting made me wonder why trains are made up needing multiple engines, instead of just multiple small trains? I can understand adding a pusher to help get a train up a steep grade.
If you do want one long train, I can understand putting the engines in the middle of the train to reduce the load on the couplers. So why one long train?
greg - Philadelphia & Reading / Reading
Simple...since all locos can be controlled from the head one,less manpower needed for the same loads.Multiple trains mean more operators and so on.......
Its cheaper, plain and simple. Fewer trains means fewer crews. Bigger trains means fewer trains or more goods moved. A 5000 ft train has the same "dispatching footprint" as an 8000 ft train. So you can move the same number of 8000 ft trains over a territory as you can 5000 ft trains. That is HUGE in cost reduction and carrying capability. Even increasing the length of a train by 5-10 cars is a huge increase in efficiency. Its more fuel efficient. Once you punch the hole in the wind, incremental cars can be moved for minimal fuel.
Dave H. Painted side goes up. My website : wnbranch.com
dehusman Its cheaper, plain and simple. Fewer trains means fewer crews. Bigger trains means fewer trains or more goods moved. A 5000 ft train has the same "dispatching footprint" as an 8000 ft train. So you can move the same number of 8000 ft trains over a territory as you can 5000 ft trains. That is HUGE in cost reduction and carrying capability. Even increasing the length of a train by 5-10 cars is a huge increase in efficiency. Its more fuel efficient. Once you punch the hole in the wind, incremental cars can be moved for minimal fuel.
Not in disagreement here but a couple of points... based on the thought that IIRC the initiating thread was about double heading steam... (anyway it would apply to double heading steam and diiesel not fitted with MU jumpers)...
Fewer trains - at least runnig locos in multiple - means fewer crews and therefore saves on cost... but this doesnt apply to steam and non-multiple diesel (we call it running the disels in tandem rather than running them in multiple). US practice is to run lts of tandem consists but I have often wondered what is going on when I see a swticher in the middle of a consist... I do know that some switchers are fitted with Mu connections...
Another "detail" - " A 5000 ft train has the same "dispatching footprint" as an 8000 ft train. "... sort of... It is very era specific. In earlier eras passing sidings tended to be shorter... due to 2 things 1. the size of the train expected to be run at the time they were installed (which had a lot to do with traffic demand and the size/power of locos available at the time) and 2. the control of switches - (theres lots of options here... but one major point is that for a train to stop, line the switch, enter and re-line the switch adds time to the footprint. Similarly lining switches to get out of a loopp and then stopping to retrieve the caboose crewman who has reset the switch behind the train also takes time). This all goes into the dispatching footprint.
The thing is that, in earlier eras at least, A RR might opt to dispatch 5000ft trains because they fitted into passing sidings more conveniently. An 8000ft train might only fit into some sidings... without messing about with saw bys or splitting the train... all of which would take time... increasing the longer trains footprint. From a modelling point of view the theoretical length of available passing sidings may provide a convenient excuse for running shorter trains.
One dispatching option is to run short trains in one direction (tucking them into the sidings) and run longer trains in the other direction - usually letting them stay straight on the main track.
Got to go to work now... but the significant concept over all is what we (and I think US RR) call "Headway". Headway is the standard time specific trains take to get through specific lengths of the line. The most restrictive headway is the one that can tie up the line but is the one that is worked round to manage traffic flow.
Dave-the-Train Not in disagreement here but a couple of points... based on the thought that IIRC the initiating thread was about double heading steam... (anyway it would apply to double heading steam and diiesel not fitted with MU jumpers)
Not in disagreement here but a couple of points... based on the thought that IIRC the initiating thread was about double heading steam... (anyway it would apply to double heading steam and diiesel not fitted with MU jumpers)
I took the original post in this thread to mean modern trains since he was talking about multiple engines, but on re-reading it, you are correct it wasn't very specific about what the OP was asking.
True. My answers were oriented to current operations. If you want to back date them then I get to backdate the train sizes to be era appropriate too. Lets just cut to the chase and say a train less than the standard siding length has the same dispatching footprint as a trains that is the standard siding length.
My use of "footprint" implies space but if you want to include time, we can do that too. I disagree some with the premise concerning the time it takes to head into a siding. Yes it will take longer for ONE 8000 ft train to pull into a siding compared to ONE 4000 ft train. But if you compare ONE 8000 ft train to TWO 4000 ft trains (the same amount of business), then the difference will be much less significant since the deceleration and switch lining times will be doubled.
US roads usually use "headway" to mean the time between trains passing a point in the same direction. So if I stand at the east end of the siding and a westbound train passes me every 15 minutes, then they are on 15 minute headways.
If the OP was talking about steam era and was talking about trains with helpers and the real question was, " Why don't railroads break up trains into smaller trains to go up hills instead of adding or cutting in pushers/helpers?", then the answer definitely is:
1. Larger dispatching footprint for more trains.
2. Increased asset demand (every one of those individual trains needs a caboose).
The trains described having 6 or 7 helper engines going up a hill aren't necessarily "long" or "longer" trains. They might be the standard size trains that just need that much power to get up the hill.
As an aside to the OP, the P&R/RDG was engineered so a locomotive could move the same number of coal loads from St Clair to Philadelphia as it could empties from Philadelphia to St. Clair.
"If the OP was talking about steam era and was talking about trains with helpers and the real question was, " Why don't railroads break up trains into smaller trains to go up hills instead of adding or cutting in pushers/helpers?", then the answer definitely is:
As an aside to the OP, the P&R/RDG was engineered so a locomotive could move the same number of coal loads from St Clair to Philadelphia as it could empties from Philadelphia to St. Clair."
To use a real life example from the late steam era, on the B&O, on their orginal mainline west out of Baltimore, commodity frieght trains of 4000-5000 tons, usually 3500' long, 50-70 cars, would be pulled by two Mikado's from Baltimore to Brunswick. That line has 1% grades and a few sharp curves.
The line was double track, so siding length was not much of a controling factor other than for staying out of the way of passenger trains.
At Brunswick, the two Mikados would be replaced with two 2-8-8-0's or two 2-8-8-4's for the trip over the Allegheny summit. And the main grade there would require a helper or two.
Once over the mountains, smaller power easily handled the train across Ohio into Cincinnati.
Larger power was not used out of Baltimore because curve restrictions would have slowed speeds too much. Smaller trains would have, as Dave pointed out, increased the traffic footprint and consumed more assets. And, in the days before radios, many lines considered the extra bodies of the extra crew a good safety precaution.
So double heading was the order of the day, not just for a hill or two, but for the whole subdivision run in this case, about 70 miles from Baltimore to Brunswick.
Sheldon
"...since he was talking about multiple engines..."
A trap to fall into But useful to me as it raises the question of how the different eras (and loco types) would describe their working.
For us with steam we would just talk about double heading for two locos. Anything more would be so unusual that it would get spoken or written in detail - and everyone would be looking at it as it went by - especially small boys of all ages.
So to be distinct from diesels lashed up in multiples how would numbers of steamers working together be described please?
In fact running more than one loco together was so odd that light loco moves - engine hops - were described forward as either a "light loco" or "two light locos". Anything more got described as "two light locos" with the following description of "loco assisting in rear" or "two locos assisting in rear". IIRC this could be repeated up to a maximum of six locos moving together.
This isn't as uselessly non American as it might look as it wanders me onto the point (that might be useful to the OP and other modellers) that (unlike the working examples given) sometimes the grades or flow of traffic caused an inbalance of locos at opposite ends of a division. Sometimes this was sorted out by running more locos than strictly required on the head of trains working down grade or in the light traffic direction... and sometimes it was resolved by working train hops of several locos... makes for an interesting "odd" move - especially with steam.
I think that when talking about headway we are talking about the same thing looked at differently. The static observation is a different perspective on the same thing "over the road".
Something I picked up on very early in looking at US RR was that while (with our short distances) we tend to run alternate directions as required US practice (on Single track) could be to run eastbound on Monday and westbound on Tuesday. All that then had to be done was to keep the trains from catching up with each other ... or sending out Orders to put slower freights "in the hole" to let overtaking fast traffic go by them.
I'm still fascinated by the US practice on Double track of putting traffic over to the "Wrong Main" (or Opposite Main) to get faster traffic round slower traffic. I love this especially when a really slow drag is switched across to roll Opposite Main to let varnish or mail whiz through without slowing to change tracks.
(Don't know if you call it "wrong main" ... may be some of our language creeping in there).
I do see the sense of keeping the footprint large both for headway and costs...
I wanted to add the detail because some of the details of how things used to be done - especially in steam days - can be so easily lost... which is a pity because they are so interesting. Just lashing on more power in multiple and adding DPUs is easy but much less interesting.
Dave-the-Train So to be distinct from diesels lashed up in multiples how would numbers of steamers working together be described please?
Double headed.
We really don't have anything special for the number of engines in consist other than "mulitple unit" or "consist" since in the US it is not unusual to operate a train with multiple units. We actually worry more about one unit trains than multiple unit trains. We might describe a F unit consist as A-B-B-A or A-B-A or a DP configuration as 2x3x3, but I don't think that's the same.
It is common for the maximum number of units in one place on a train to be limited to around 8 (varies by road and era) and a typical number for light engine moves is 25 max.
That's interesting. In 30 years of prototype operating experience, I've never heard or seen an example of that type of operation, except in some sort of disaster recovery mode (or a line that just runs one train a day). You are probably confusing a "tri-weekly" local or tri-weekly crew rotations with the overall train operation. The local train (one singular train) might operate east on Monday, west on Tuesday, east on Wednesday, etc. But the other 20 or 30 trains a day on the sub are running in both directions every day. Individual crews in a pool will work that way out one day, back the next, but there are dozens of crews so on any given day about half are working east and about half are working west.
On double track you would want to put the slow train on the wrong main, on CTC two main tracks you would want to put the faster train on the other track. The wrong main in double track is limited to 49 mph while the main with the current of traffic is max speed, plus the crossovers will be most likely 10 mph hand throw crossovers. In CTC the max speed on both mains will be the same and the crossovers will most likely be 30 mph or higher and power operated.
I think that the running one way one day and the other way the next was something I read right at the start of looking at US material... but the first stuff I looked at was engineering and RR magazine type publications of the 1880s up to about 1905... maybe 1914. I think that counts as an early period [I should have made that clear] and possibly a little bit before your time Dave It was a touch before mine Of course there was probably both a far higher % of single track and much less traffic back then - especially way out on the Prairies. I guess that some of the long lines out into grain country or to cattle railheads may have worked pretty much like locals.
I can't recall the exact term I read/heard for at least the same period - it was something like "smoke rules". When /where there was extremely little communication the caboose crew of a struggling train would leave "torpedoes" as warning to following trains but (in daylight) the engineer would also "make smoke" to give a marker of where his train was.
I always wondered about the safety of dropping what amount to flares on the track in the summer especially in grasslands... but I have seen recent video of US police marking road incidents with something similar.
There was also some recent film on here of a layout where the modeller had simulation of a flare dropped on the road for a switch move to cross a grade crossing. It looked tiny but really neat. (Anyone recall the link please?)(or who makes the little "flashing" lights)?
What happens with these things in snow??? Don't they just melt their way in and hide themselves?
I guess that if a train set fire to lineside grass there was a pretty good marker to where the train was / had been.
Could Alcos work with "smoke rules"???
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I never remeber to get my head round lining switches by hand to change tracks on the main. It seems really weird to me. Due to everything we have being squashed up close everything in main track except Engineers' connections that are normally locked out of use (or anything actually taken out of use) is worked from a tower or an extension of one.
Thanks for the speed limit information. Speeds are something I am aware of and something I was trying to put across in connection with headway. As you say the decision on which line to run trains of different speeds on is directly linked to speed limits on the track and through connections. I think that for modellers that like to operate this adds really interesting dimensions.
I have had great fun running on club layouts... first trick (with permission) is to run CNW consists right direction (for them) on them on the left hand track. When people have got used to that I have run ATSF wrong main. I so rarely see modellers putting varnish past freight in this way... and it looks so good.
Most locos I've ever seen lashed together for a light move was five (class 57s probably) The noise was ridiculous by our standards.
"We actually worry more about one unit trains than multiple unit trains".
That confirms something I strarted to figure out some time ago.
Looking at video of shortlines and/or similar I noticed how often even quite short trains ran with a couple of units - often two quite small GPs instead of a single SD. I put some of this down to what the track and bridges could take but also guessed that - when a train is miles from nowhere - providing two units means that if one conks out the crew has some chance of limping home.
(I know that back in steam days a single steamer with trouble on one side could somtimes have an appropriate rod taken out to allow the loco to struggle home on one cylinder. I have actually heard old steam drivers complaining about diesels that if something broke the things were stuck and you couldn't get home until something was sent to shove or drag you the rest of the journey (or to a depot). It was taken for granted that whatever broke always did so on the days that you wanted to get home for a football match or similar.
Something I recalled last night...
I think that I heard or read that coming over the Rockies at least some trains have higher numbers of locos (at least on the point) not so much to give them the power to get up the climb but to provide additional dynamic braking coming down the miles and miles of down grade once over the top. Is this right?
Thanks
One advantage diesels brought was the ability to use engines as "building blocks" to create the right horsepower for a train. In steam days, you might have big Mallets for long (but often slow) mainline freight trains, Berkshires or Mountains for higher speed freights, Mikados and Consolidations for ordinary freights...you had to have the right engine for the right job. With say EMD GPs, you just add the number of GPs you need - one GP for a local freight or for switching, two for a medium sized freight, 3 or 4 for a long mainline freight. Order them with steam generators and you can use them on passenger trains too.
"Wrong main" running only applies to operations on double-track ABS. In this operational setup, each track has a specifically desginated DIRECTION OF TRAFFIC, and will have automatic blocks signals ONLY in the direction of traffic on that track.
Any train put on to the "wrong main" AGAINST CURRENT OF TRAFFIC will run under speed restrictions since it does have any block signals on its track (they all face the other direction only).
With modern CTC operation, all tracks will be fully signalled in both directions so there is no current of traffic to take in to account. Trains can be run on either track in either direction at full speed.
Chris van der Heide
My Algoma Central Railway Modeling Blog
cv_acr "Wrong main" running only applies to operations on double-track ABS. In this operational setup, each track has a specifically desginated DIRECTION OF TRAFFIC, and will have automatic blocks signals ONLY in the direction of traffic on that track. Any train put on to the "wrong main" AGAINST CURRENT OF TRAFFIC will run under speed restrictions since it does have any block signals on its track (they all face the other direction only). With modern CTC operation, all tracks will be fully signalled in both directions so there is no current of traffic to take in to account. Trains can be run on either track in either direction at full speed.
Not really disagreeing, because in many cases your are correct. But, all such assumptions are era and railroad specific. Some railroads did have double track, double direction, ABS systems.
It seems very easy for many rail fans and modelers to assume everything is/was like the prototypes they are familiar with. Signal systems and operational rules have been as varied in North America as there have been different railroads.