I, too, have seen double P-42s many times on a train that didn't seem to need them for power. I think the extra locomotive is frequently for reliability, especially where there are long stretches without any significant maintenance capability that could react in a timely manner.
Another issue besides Amtrak on-time performance is the possibility of tying up the whole RR if an Amtrak single-loco train breaks down in the middle of nowhere. They can't just send out a "tow truck" (another engine), even if one were available, because there would almost always be freight trains in the way. I can see why Amtrak would want to avoid that scenario anytime they had a second locomotive available to put in the consist.
At least once a month I hear on the radio talk of a freight locomotive with a problem on the BNSF Madill Sub, and the train is stuck while Fort Worth Mechanical talks the crew through troubleshooting and workarounds. Every once in a while they have to isolate the unit and carry on with one fewer operating locomotives. The "local" comes by here with 10-20 cars and two GP-38s. I almost never see a single locomotive here.
Important point to remember about E-units is that they were two engine-generator-motor sets in a single carbody. A 2-unit E set developed 4000-4500 hp for traction and would deliver 3/4 of that if an engine quit. A pair of F40PH units would deliver the same hp, but would be far worse off if one quit. A pair of P42s is better, but not by much, as one unit would achieve the hp of one and a half E units. A single P42 isn't equivalent to a pair of E units, as some of its power is lost to HEP.
A "modern" E-unit equivalent would have a pair of 8-cylinder 710 engines in one carbody.
Paul Milenkovic That was my original point perhaps. Are Amtrak consists carrying extra locomotives because there is a high failure rate on their locomotives? Would it be reasonable to dispatch a single locomotive unit on an LD train if it could handle the train, or do you need locomotive redundancy? If you need to carry two locomotives on an LD train and don't really benefit from "unit reduction" form the newer higher HP P42's, what does this say about locomotives or about maintenance practices?
That was my original point perhaps. Are Amtrak consists carrying extra locomotives because there is a high failure rate on their locomotives?
Would it be reasonable to dispatch a single locomotive unit on an LD train if it could handle the train, or do you need locomotive redundancy? If you need to carry two locomotives on an LD train and don't really benefit from "unit reduction" form the newer higher HP P42's, what does this say about locomotives or about maintenance practices?
That is an interesting point I have ponderd myself. But if you consider two E8's were 5000 hp or three F units were 4500, then the horsepower ratio is probably within the same limits for size and terrain?
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If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Rode California Zephyr once out of Denver and two of three locos failed and HEP was turned off so we could climb east range to Moffet tunnel. Then HEP turned out. Got to Glenwood and engines restored. suggested to conductor that he get a helper engine at helper in case of another failure. He Didn't think necessary and the two engines failed again. Conductor adimitted mistake .Into Salt Lake 5 hours late and Salt Lake crew not notified of late and they got caught on HOS some where west. What a mess.
Oh passenger trains would get helpers on grades quite often. NYC would use a switcher to push the hind end of westbound passenger trains out of Albany, for instance, and longer grades with long trains would receive pushers or helpers just like the brawney brother the freight train. HEP is a newer technology, but yes, I believe I heard of engineers pulling the plug on the HEP so to speak in order to take full power output of the engines. This has changed now with HEP often comeing from a different source than the prime mover. Your assumption is not that naive.
My naive assumption was that they need the extra locomotive for steep grades and HEP. I read a trip report where the author noticed the HEP turned off on a steep grade more than once. I don't think Amtrak has the means or logistical capability to provide helpers.
Doesn't this all go back to the old argument about horsepower and tractive effort, wit acceleration thrown in for good measure? If you want a train to go quickly, and even more so go quickly up a hill then lots of horsepower is needed. And do remember also that wind resistance increases wi the square of the velocity. So if you want to go really quickly then lots and lots of horsepower is needed - as High Speed trains all over the world will show.
To give an example to get 600 tons of train up grades of just under 3% in Switzerland requires around 10,000 horsepower. 10,000hp will get lots more tonnage up at 10mph.
So returning to the questions they key determinant on transcontinental railroads will be how fast you want to (or can) go up your grades. If you want and can go up quickly then lots of HP will be needed, and that HP will not be used for most of the journey. On flatter journeys the key issue will be how quickly you want to get up to 79mph, and on the North East corridor how fast you want to go in absolute terms.
Putting 20,000hp on a train from Chicago to New Orleans will get it up to crusing speed more quickly, but as crusing speed is 79mph max then the extra 12,000+hp will be wasted. Puting the same HP on the EB will get it up ills real quick, and probably deail the train round the curves. Putting it on a hig speed train gets you an average speed of c150mp and max of up to 200mph.
henry6 As with any train the number of locomotives is decided by terrain, track, schedule and speed needed to maintain the schedule, weight (with passengers), total horsepower needed for train, weather conditions. Thus a 1000hp switcher capable of 40mph with two coaches would not make it on a 22 car consist of light weight streamline cars and a couple of heavy weight six wheel truck antiques over 2%mountain grades and flat land tangent speeds at 90 mph. Each railroad had its specified locomotives for specified uses, singley or matched up. And as the units got older, worn out, and less reliable, the more units were added. Thus, for example, a pair of E8's in 1952 warrented three E8's by 1965! Sometimes, too, depending on the axel count vs union contract, a spare unit could be added as an equipment move.
As with any train the number of locomotives is decided by terrain, track, schedule and speed needed to maintain the schedule, weight (with passengers), total horsepower needed for train, weather conditions. Thus a 1000hp switcher capable of 40mph with two coaches would not make it on a 22 car consist of light weight streamline cars and a couple of heavy weight six wheel truck antiques over 2%mountain grades and flat land tangent speeds at 90 mph. Each railroad had its specified locomotives for specified uses, singley or matched up. And as the units got older, worn out, and less reliable, the more units were added. Thus, for example, a pair of E8's in 1952 warrented three E8's by 1965! Sometimes, too, depending on the axel count vs union contract, a spare unit could be added as an equipment move.
Johnny
In the days of the F40's, if a train was over 8 cars with 1 F40 the railroads would receive additional 'incentive minutes' on the operation of the train for On Time Performance. To be On Time at one of the designated 'checkpoints' a train could be up to 10 minutes off the advertised (or 10 minutes later than the adjusted time if the train was received late from another carrier). If I recollect correctly, for each car over 8 the carrier received 5 additional minutes that the train could be late and still be considered to have been On time at the checkpoint.
Never too old to have a happy childhood!
The ugly answer here might be that number of locomotives used might be more a function of fuel locations and range than HP/ton for schedule keeping. As the number of locomotives goes up, the fueling range increases much faster than the burn rate due to higher HP/ton and increased train weight.
Amtrak used to run 8 cars behind a single F40 on the north end of the NEC. I don't understand why Amtrak went with 16 cyl FDLs in the GEs instead of opting for 12s. I'm not certain that extra HP really produces any value for them.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
It too seems to me that Amtrak overpowers certain trains but that got me thinking. Prior to Amtrak how did the RRs power the streamliners.
The GN first streamlined the Empire Builder in 1947 with a pair of E7s for a total of 4,000 hp. When the mid century EB was introduced in 1951 they powered it with 3 unit sets of F units 4,500 hp. Likewise for the Western Star the former EB train sets of 1947. When the domes arrived they seemed to change the way of looking at the EB once again. West of Havre the EB operated with A-B-B-A sets of F units for 6,000 hp, and east of Havre the EB operated with A-B-A sets of F units.
When the new passenger units came to the GN they were in the form of SDP40s and SDP-45s. Generally a pair of SDP40s totaling 6,000 hp were assigned to the combined Western Star/Fast Mail west of Havre and east of Havre A-B-B-A sets of F units also 6,000 hp. The EB initially received a pair of SDP45s west of Havre in the summer months for 7,200 hp and winters a SDP45 and FB unit was the norm for 5,100 hp. Later they mixed the SDP40s and SDP45s on both trains and even threw in F units when needed.
The NP assigned A-B-B F units originally to the North Coast Limited later A-B-A and this lasted until after the domes came when summers an extra A unit was added for the heavier summer consists. They mixed F9s at 1,750 hp with the earlier F3s and F7s at 1,500 hp and this was the way the NCL operated.
The UP City of Portland leaned toward E units and summers generally A-B-B-A E8s and E9s were the common power for a max of about 9,600 hp the rest of the year was only A-B-A E units for 7200 hp max.
The SD40Ps that Amtrak purchased seemed to operate in pairs only on most western long distant trains until they began derailing. When F40s were assigned many of the long distant trains began operating trios of these. Maybe it was the additional powered axles of the SD40P units that made the difference although that does not explain why they generally operate the P42s in pairs only. They must have more weight on each axle than the F40s. I know that the SDP40s could certainly accelerate like the wind when they were new. I don't know what criteria Amtrak uses for assigning engines it seems that some trains assigned a pair of P42s certainly do not need that much power.
Al - in - Stockton
I was browsing back issues of Trains over at the State Historical Society, and the December 1974 issue has an article by Jim Hediger titled "This highway is not on your oil company map." The article describes the operation of Auto Train, that is, the pre-Amtrak Auto Train.
The article describes some of the can do, no trade craft barrier spirit of what had been the non-union Auto Train Corporation. The trains were stocked with fuses and other replacement parts, and there were train crew members who were on-board maintenance people who were to fix things when they broke. They were working with rolling stock from the same Heritage Fleet as Amtrak, and when the A/C went out on one car, the author wrote about how the crew radioed to take a siding and a member of the on-board crew went under the car. I suppose there is also a downside to all of this "non-union, no trade craft barriers, let's roll up our sleeves" kind of approach -- railroading is a dangerous business, and there was no mention if derails and blue flags went up to protect the guy knocking on the balky air conditioner under a car.
It was claimed (back in 1974), than an auto required 90 gallons to travel the 855 miles (Amtrak timetable) from Lorton, VA to Sanford, FL. This seems like a lot of gas for a car -- did cars actually only get under 10 MPG on the highway? I seem to remember driving a Mercury station wagon in 1977 with a 400 CI (7.6 litre) V-8 engine that was good for about 15 MPG on the highway -- remember you had 55 MPH speed limits.
It was claimed that the Auto Train required 25 gallons for each auto and their passengers transported. Don't know if they made the gasoline/Diesel oil adjustment and if they were assuming a full train, but my understanding is that the Amtrak Auto Train operates consistently at high load factors. A 3-1 improvement over driving is huge, but again, the 90 gallons to drive a car seems overestimated, and today, a Toyota Camry could make that trip on only 25 gallons, so the fuel savings of the Auto Train over driving seems marginal with modern cars.
The train was described as using a pair of U36B locomotives on a 39 car train, of which, 21 cars were auto carriers. The U36B's, by the way, were standard-issue freight locomotives, perhaps with higher speed gearing, and the Auto Train tacked on a steam generator car for heat, and many of their full-length dome cars had gensets (Santa Fe High Levels followed the example of the full-length domes with gensets) for airconditioning.
Now I know this train didn't make stops other than for crew changes, and when Auto Train was running their Kentucky-Florida service, that train used a trio of U36B's on account of the mountains.
But following that level of providing power, and taking into account increased HP and better wheel slip control, a single P42 should be able to handle any consist on the Amtrak network.
It seems Amtrak follows a formula of a locomotive unit for every 5-6 cars. Do they really need that much power? Are Amtrak schedules such that they need the extra locomotive units for the extra acceleration? Are locomotives that prone to breakdown that the 2nd (or 3rd) P42 is a spare? Did Amtrak achieve any "unit reduction" with the 4000 HP of the P42 over the 3000 HP of the F40P?
The Amtrak-era Auto Train seems to be the one LD train that comes closest to breaking-even on operating costs. Does Amtrak run the one Auto Train because they inherited it when Auto Train Corporation went out of business and this is a legacy thing that they just keep doing, or has anyone ever looked into whether Auto Train service would contribute to other routes?
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