Pool Power

[dehusman]

It has to do with what the two railroads want to do with the train at the junction points between railroads. In tha ls 30 years railroads have really exploited the efficiencies of running the power through with the trains saving the time and expense of changing power at the interchange point. Depending on the arrangement the railroads may pool engines, pool sets or one railroad just provides the power. The UP provides all the power in a lot of cases on coal trains because they are DPU'd and have to have the UP cab signals.
Once the pooling arrangement is worked out then the railroads have to balance the HPHRs and that's when they start injecting free runners and non-runthru units into the mix. So the UP provides all the power on a certain set of coal trains and the other RR provides UP with other units to used in other service to pay back the HPHR's.

Dave H.

[wcfan4ever]

I think it has something to do with payback hours. If one railroad uses anothers power for a train, they return the favor and let them use thier power. Plus I think that if a train originates lets say in NY on CSX and is heading to LA, CSX power may stay on the train so a certain point on anothers track...lets say BNSF. Then BNSF takes over to LA. Once returning, the BNSF power may stay on well into CSX property and then be relieved by CSX power. I think this is somewhat how they do it.

[Junctionfan]

I think I have the terminology right.

Why do the railroads swap power on their trains and than other times they just use their own. Who decides this?

I have seen some might odd lash ups with a NS train with a UP engine, NS engine and a Montana Raillink engine. Any explanation on the what constitutes the need to even use shortlines power for long distance routes?