VERY informative post. Makes complete sense to me, especially the concern by the IRS triggering an investigation into the depreciable cost changes. The IRS DEFINITELY notices things like that.
Sometimes modernization is done for the sake of modernization. Oil was considered cleaner than coal (less smoke than a bit burning lokey and thus better for passenger trains), there was no steam effluent, and it was more convenient to fuel.
I noticed that the 1950's pamphlet for my Axeman Anderson Anthratube, it claimed a nearly 50% savings over oil even back then. Obviously, they had to use the savings as a selling point. As for its moving parts, yes, there are more on an AA than an oil burner but I don't think it will be more expensive to maintain than an oil boiler in the long run. As for its life, I know it will out last an oil boiler on the same order as the comparison between diesel and steam locomotives.
I know that my AAA is not a fair comparison to a steam locomotive and I see coaledsweat's point about the reciprocating parts. But I do also think that if those reciprocating parts were a huge problem, they could have been redesigned had the market for steam remained intact. Why not steam turbines and rotary drives with differentials?
Coal was, and is still, considered dirty and old fashioned. I think that's one reason for such changes. While the airlines presented sleek and modern looking planes humming along at wild speeds, the passenger train business was still smokey, slow and in the old fashioned steam era. I suspect that marketing motivated their switch also.
But, what goes around, comes around. Obama wants to reinvest in high speed rail. Gee, I wonder what will power it? Certainly not wind nor solar nor gas, If it's electric (third rail)...we all know that's just inefficient coal burning. If it's oil....that's more of the same. How 'bout fusion-electric. Now that would be modern, safe, clean, high tech and efficient. The only drawback with fusion is those pesky little neutrons. Oh well, nothing's perfect.
Thanks for the great posts-- both of you.