Let me explain the problem.
I have 3 different types of road loco available for a train - lets say (1960-1980 maybe - and excuse me if I get this wrong being of British extraction :-)
an RS-3 HP = 1,600 - Tractive Effort 61,775a GP9 HP = 1,750 - Tractive Effort 64,750a GP30 HP 2,250 Tractive Effort 63375
What would be the basis for selecting one or other of these. Would it be purely on HP or tractive effort?
The reason I am asking is because I am building a freight car routing system and having generated a number of cars that need to be put on a train, I now need to select a loco to be the pm. If these three are available as road switchers, why would I choose one or the other - assuming that the load was within range?
If the load was out of range and thus needed two locos, again, what would be the criteria? (assume that we had more than one of each available).
If the question doesn't make a lot of sense, you can see where I am coming from so perhaps, in those circumstances, maybe you propose the problem in a more realistic way?
David
Main man on the S&NE
Long Haired DavidA.K.A. David Penningtonmain man on the Sunset and North Eastern R.R.http://www.gmrblog.co.ukfrom the UK
Having had two different jobs that assigned engines on a class 1 railroad, my answer is it doesn't matter, all those engines would have be essentially the same as far as the railroad is concerned. About the only difference is that the GP30 is newer so it would probably go on whatever train was the highest priority, plus having slightly higher hp it would accelerate a tad faster.
First you would pick one that was at the yard, next one that was serviced and ready to go. You would pick the one pointed the direction preferred and if you were going to pick two you would pick the pair that was already put together (less work) and probably a back to back set.
Dave H. Painted side goes up. My website : wnbranch.com
A engineer told me in the simplest form its HP vs.tonnage vs.the ruling grade and weather. A ruling grade could be no more then a sharp curve on a point 5% grade or it could be a stiff half mile of 1.5%..Now add rain,snow and ice then more HP may be required.
A example would be C&O ran 180-230 car coal trains between Russell, Ky and Toledo,Oh with three to four GP9s.While on the Big Sandy those trains would require six GP9s due to the grades.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
If the train is 20 cars or less, a single unit is used. if the train is longer that 30 cars, three units are used to cope with the extra load.
The six axle units are used for mainline runs, while the four axle power is used for hump service, yard switching, short locals, and assembling trains.
ATSFGuyIf the train is 20 cars or less, a single unit is used. if the train is longer that 30 cars, three units are used to cope with the extra load.
Psst! Don't tell NS that..I seen one unit on 40-50 car trains.
About six axles..That would depend on era..You nail it for today's railroads but,back in the day 4 axle units was widely used.
CR used GP40-2s on some of their TV and Mail trains.
Don't tell UP either. Most Class 1s want to do more with less. You may see 6 locos on a train, but 1 could be Dead Bad(DB), 1 could be being ferried to somewhere, others just down for power or isolated not in use because the Power Desk deemed them not necessary for that leg of their journey. Tonnage, tractive effort and dynamic braking are all factors indetermining power usage. They also have to take into consideration Territory Restrictions, Weather Conditions, etc.
I think that programming in things like that and something that was suggested on another forum viz. "Management preference - the Boss is likely to prefer the loco that is cheaper to operate, or he might prefer to run one loco for the remainder of its maintenance interval so it can be sent to the shops" might turn the process into a computer game rather than a real processing tool for a model railroad. but it is interesting, none the less.
[slightly off-topic but along same subject]
Just so happens, I was working on something yesterday and came across a Google Earth view of two trains on Pan Am/Springfield Terminal Railway (Vt.) tracks between Valley Falls, NY and Johnsonville, NY in September 2013 (not the more recent years).
https://gyazo.com/a1a7e33499325c8144b5d3ab095522e2
1st: 4 locos, approx. 71 cars
2nd: 4 locos, approx. 74 cars (mid-point of consist is under Valley Falls bridge across Hoosick River)
approx. 0.31 miles apart
I thought it strange the trailing train would be so close to the leading one. Does this seem safe? Then I wondered, what grades and powerplants were involved? Rhetorically, thinking.
olson185I thought it strange the trailing train would be so close to the leading one. Does this seem safe?
Yes,been there done that on the Chessie(C&O)..You proceed at restricted speed,looking out for the train ahead and be prepared to stop short of the train ahead.
As a head brakeman I always hated doing that especially in a thick fog..