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That NPS claim of 3,800 tons at 40 mph "across the mountains" is preposterous. The physics alone would require at least TWO Big Boys, maybe three or four. Ruling grade on the Wyoming Division in either direction is 0.82% (not HELPER grade). Grade resistance for 3800 tons on 0.82% is 62,320 lbs. Rolling resistance using LS&MS empirical tests would be 16 lbs. per ton at 40 mph, or 60,800 lbs. Total tractive effort required uphill at 40 mph would be 123,120 lbs. HP = (speed x tractive effort)/375, or (40 x 123,120)/375, or 13,132 hp! At 20 mph, rolling resistance would be 7 lbs./ton. That gives a HP requirement up the 0.82% grade of 4,742 HP. Now we're in the ballpark. I think an average speed of 15 mph between Evanston and Hermosa Tunnel either way, including start and stop but discounting all meets and temporary speed restrictions, is more likely. Add a helper westward from Cheyenne and eastward from Ogden. OS
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