My understanding is the axle count cars are need to trigger the grade crossing protection. Not so much for the PTC system. There are ways of doing this better, but money would be needed.
No idea how the freight railroads are getting away with this. Seem a bit dodgy.
I think they also trigger signals (and systems relating to signals) as well, not sure though.
What is unique about the CN’s track/signals that require a certain number of axles but is not required on other railroads? I would have thought improvements associated with PTC would have eliminated any outdated practices.
UP also has them, the Missouri River Runner and I think the Lincoln Service has run with many unused baggage cars to meet their axle requirement. In fact, I wouldn't be surprised if almost all railroads have them, it's just that the midwest (and the routes named above) are the the only trains with revenue consists that are too short to trigger it, therefore requiring extra cars.
At present a quick count suggest that less than half the total fleet of SSLs are currently assigned to trains,
Is this the total ordered originally (so all 50) , or the total amount that can actually go out on runs in the present day (so only the ones which have not been wrecked/out for maintenance)?
Not for axle counts in California, but to replace the cafe cars when one is out of service. Still a stupid way to use them, they should just try to get a superliner coach-cafe. The Surfline may be a wonderful train, but theres really not that much beach scenery south and it's only a three hour run so...