Still, most of that stuff doesn't make sense to me....
Cal Zephyr: 2-3 Genesis locs (8000-12,000 hp?) 10 cars @ 74 tons per Superliner = 740 tons. + engine weight (122 tons X 2-3 = 244 - 366 t) = 988 - 1106 tons. 4 sleepers X 35 passengers = 70; 5 coaches at 90 per car = 450; total = 520, top speed 110 mph?
First off, to the best of my knowledge except on the Northeast Corridor, the max operating speed for most Amtrak as limited by tracks is 80 mph (or 79, if you insist). I do believe that certain trains, such as the Southwest Chief, do hit 90 at times because some of the track they run on is Class 5 track. I was talking with an Amtrak engineer once and I asked him the locomotive question, he didn't know the definite answer, but he did say that sometimes the Southwest Chief will operate on one engine, it just take a while to get to 90 on one engine, but you'll still get there. I don't believe the California Zephyr goes any faster than 80.
Amtrak has fuel saving instructions in place and locomotive assignments are a function of a combination of things: fuel consumption, power requirements, HEP eliability, grades and train weight. One item not mentioned is the fact that the P42's are much lighter than freight locomotives of the same horsepower rating and are therefore, a little more slippery with a poorer factor of adhesion. The fact that the locomotives are geared for passenger speed reduces the power output at the rail in terms of acceleration, i.e, these engines are built for speed, not lugging ability and as such are much more sensitive to train weight.
Locomotive failure, schedule demands, and its Amtrak...
Regarding locomotive failure, wouldn't it be cheaper just to have better maintenance than it would be two run another locomotive? Not to mention all the money you'd save for new routes if they didn't have to buy new locomotives... And regarding schedule demands, well if only 1 loco was scheduled and they had another free one, wouldn't this make the schedule more flexible? Scheduling 2 locos puts more strain on the schedule, not less....Locomotive maintenance is an issue on all railroads, and as it goes, Amtrak does a pretty respectable job of maintaining what can be considered an elderly fleet. The schedule is what it is, and the power assigned is based upon many factors, both permanent and temporary, schedule being just one part of the equation.
The Empire Builder is pulled by two locomotives from Chicago to Spokane, where the train is split into Portland and Seattle sections. One locomotive is used to power the Portland section, whilst the other powers the Seattle section.
Now that kind of makes sense, if they are going to be spilling the train, but wouldn't it be cheaper just to store a locomotive in Spokane instead of running it every time to Chicago and back?The Builder contends with one of the toughest grades in Montana and two units are needed to power the train on that grade and maintain that nasty old schedule. Remember, HEP reduces the second unit's traction output considerably, more than the 700 hp quoted elsewhere.
Don't forget that as much as 700hp. is diverted to providing hotel power to the train. Then you have situations like on the climb out of the Colorado River basin to the top at Yampai Summit, over 100 miles of near steady 1.4% which all but the hottest freights climb at 25 - 30 mph. and Amtrak climbs at 70 mph. And then consider on a route like that if you lose a Diesel you have no AC in the summer and no heat in the winter if you have only one locomotive.
Don't all passenger locomotives have head end units which provide the electric power for the train? And those units are separate from the prime mover, correct? I know that if you look through the back door of a genesis loco you see a second, smaller diesel in the back room. Also, regarding speeds through the mountains, if a helper loco is truly needed to maintain speed on a grade, wouldn't a helper district make much more sense than running the locomotive the whole distance to and from Chicago?Head end power as provided by an Amtrak P42 reduces the horsepower available for traction by considerably more than the 700 hp quoted above. What you see in the back is in fact the air compressor and its components and a small generator which develops HEP off the prime mover. There is no auxiliary diesl engine on a P42.
FYI I'm not trying to offend anyone for the posts and thank you very much for giving feedback, I'm just playing devil's advocate here, and I'm trying to find the correct answer!