Why are they running 2 or 3 different loco classes on this service? I know the Gs and XRs seem to be packaged together for Victorian running (im assuming they provide a nice level of HP etc). But why not use a more consistent fleet on the service? And yes, I know the Gcl and 81cl (as well as the BLcl) are the same more or less) but theyre still just that bit different no? Or are they really in essence the same?
Locos are rostered to haul the load at the required speed, taking into account compatibility between classes eg continuous speed ratings. This will be more or less important depending upon locos and the road and may result in load hauling being less than the combined loads for the locos involved.
Back in the days CLs and 4 motor GMs were more compatible than CLs and 6 motor GMs for example. There used to be some lash ups of mainliners and 48 class where in total load hauling the 48 was of very little use.
Loco fuel capacities need also to be taken into account eg the BLs have a far greater range than 81s and Gs and, as such, always seem wasted to me on the Long Island steel trains.
Some trains appear overpowered but one cannot tell what may be offline but be required for return loading.