Are there any other restriction on the type or age of the locomotive that a railroad is allowed to share?
Whenever I see locomotives from other Class I railroads on BNSF, Union Pacific or Iowa Interstate tracks around town, it is usually a newer locomotive. My limited understanding of railroads leads me to conclude that I see modern locomotives (made since the 90’s like SD70s, Dash-9s), since there are more of them in service at this time compared to locomotives from previous decades & since the newer locomotives are rated at higher horsepower compared to diesel locomotives from earlier decades, a railroad could meet their “Power Pooling” obligations by sharing fewer modern locomotives.
But are there any other reason why I don’t see Norfolk Southern SD40 locomotives or Canadian Pacific EMD 710-ECO rebuilt locomotives (SD30 or GP22) on other railroads?
These are just my opinion,
Thanks,
Naveen Rajan