how far do locomotives pull their train? From source to destination or do they get exchanged?
I know there are many variables, such as where is the commodity received and where is its destination. If the runs are relatively short, then it makes sense that the same locomotives are in command of the train the entire distance, BUT what if it is a stacker that leaves Vancouver and is destined for Toronto? Aside from helpers that would be required through the Rockies, do the same engines pull this train the entire distance?
Engines stay on the train from origin to destination. That doesn’t necessarily mean the cars are one train from origin to destination, manifest cars (general freight) may be on many trains between origin and destination. Bulk trains (grain, coal, ore, oil, etc) tend to have one train from origin to destination. Intermodal cars tend to be on one train from origin to destination or interchange.
A road engine can run about 1000 miles on one tank of fuel (YMMV). There are some trains that operate coast to coast with the same power, they just refuel the engines 2 or 3 times on the trip.
This is different than in the steam days. The Broadway Limited would drop its GG1 at Harrisberg, and the frequently assigned two K4’s would run to Crestline, with a T-1 to Chicago. Yes, sometimes the two K4’s or a T-1 would run through, but very often, they swapped power at Crestline. The Central was simliar, Harmon - Colingwood (east of Cleveland) - Chicago. On the AT&SF power usually changed at La Junta, sometimes at other locations in addition. And these were considered long runs for steam power, and most freights had shorter runs. Earler in the 20th Century runs were even shorter, possibly ten changes between Chi and LA.
There might be an exception however. A very large railroad may do what the PRR did and assign classes to a specific enginehouse for repairs and monthly inspections. So a train travelling from a to c might get its engines switched at b if that was home base and an inspection was due. Steam engines were assigned to divisions and stayed within them for the most part.
I remember an article in TRAINS more than a few years ago in which the author enjoyed a cab ride on both the “20th Century” and “Broadway” from New York to Chicago. On PRR, after swapping electric for steam at Manhattan Transfer, locomotives seemed to be changed at every division point. On NYC, you had an electric from GCT to Harmon, a steam locomotive through to Cleveland, a CUT electric through Cleveland and a steam locomotive through to Chicago.
ATSF was one of the pioneers on very long runs for steam locomotives.
Not all, but some Union Pacific Sunset Route locomotives are swapped out for servicing in Tucson, Arizona, and possibly at other locations during their cross-country trek between California to New Orleans.
In today’s world of railroading, presuming a unit train in high volume service gets a set of power fresh off their required 92 day Quarterly inspections and no failures during the following 92 day period - the power would remain on the same unit train for the entire 92 day period, getting fueled, sanded, toilet maintenance, routine running repairs (brake shoes etc.) enroute. True reality, may be somewhat different, but the aim is to keep the power making money hauling trains and out of the shop.
US freight railroads generally try to avoid changing power on a train, so the typically the power will run all the way from the train’s origin to the train’s destination.
Stopping and doing anything that can be avoided, is just a complication, wastes time and money, and is another thing that can cause problems.
Consequently, railroads try hard to standardize their locomotive fleet so that any locomotive can go anywhere. For example, CSX and NS have only a small portion of their railroad equipped with cab signalling but a huge chunk of their locomotives are cab signal equipped.
I do not believe the cab ride CSS&SB mentioned was on the 20th Century. In all the days that the Cleveland electrification existed, and certainly all through the steam era, the Century did not stop in Cleveland (check any OFG of the period) ran via the lakefront, and was inspected with a possible engine change in Collingwood, an eastern suburb of Cleveland. There were through trains that met the description, but not the 20th Century. Rode it. Another train that bypassed Cleveland similarly in the steam era was the New England States, which of course was descended from the Century’s Boston Section.
Remember, too, that steam engines tended to be acquired for fairly specific purposes. Besides the maintenance specialization, the locomotives tended to be designed/purchased to run over a specific territory. It made no sense to run a flatland locomotive in hilly territory, and vice versa.
While it may have happened, steam locomotives generally did not wander off home rails, either. One factor would have been the fact that the fuels used by the railroads varied - an engine terminal likely would have had to have the appropriate oil(s), and perhaps a couple kinds of coal.