I have noticed that passenger trains seem to use a high number of locomotives for relatively short trains. Besides the obvious advantages of having backup power available in case of a failure is there a reason railroads do this? It certainly doesn't take 3 P-42's to pull a 15 car train.
Part of it is providing HEP (head-end power). IIRC Amtrak's rule of thumb is one engine for every five cars. Remember everything in the passenger cars works from the engine's electrical power - lights, A/C, heat, ovens in the dining car, etc.
oarb00 I have noticed that passenger trains seem to use a high number of locomotives for relatively short trains. Besides the obvious advantages of having backup power available in case of a failure is there a reason railroads do this? It certainly doesn't take 3 P-42's to pull a 15 car train.
Part of it is the power diverted to heat and light the passenger cars, about 800 hp. the rest is to run at higher speeds on the grades that will be encountered. BNSF will be satisfied climbing Stevens Pass in Washington State at 10 mph, Amtrak wants to climb the same grade at 25 to 30 mph where the curves will allow that speed. To achieve the higher speed requires a much higher power to weight ratio, and remember that 800 hp has been diverted for train utilities. Amtrak likes to have about 6 hp per trailing ton on the western trains, the most important BNSF Intermodal trains get about 4 hp per trailing ton, drag freights and unit trains may have 1 hp per ton or a bit less.Time is less important to freight than cost.
For example on the Soo Line's flat River Subdivision a 4400 hp AC4400CW is rated to handle 11,000 tons or 2.5 tons per hp. or another way 0.4 hp per ton.
Another reason is that freight locos are geared for top speed about 70MPH. All P-42s and the P-40s that are being rebuilt are geared for 110 MPH. This higher speed gearing takes more HP for acceleration and climbing hills than freight locos. This is so that all locos can be used on any route. the only exception is some locos still don't have cab signaling / ATS for operating on all RRs. The P-40s are getting that installed during overhaul.
All P40's and P42's came with cabsignal/atc and the ATSF type trainstop right from factory.
Whats being installed now is either ACSES or the Michican type PTC something like ITC .......
Horsepower also equals acceleration from stops and speed restrictions. Its all about power to weight ratio for passenger service. One P42 may very well have enough power to keep the train at track speed on a particular route, but it isn't going to get the train up to speed as fast as two additional units will.
Passenger operations and freight operations are two different animals.
Speed kills. In more ways than one.
A person's time is valuable. And that person will pay to save his/her valuable time. A load of coffee doesn't need to save those hours. That's why the best rail freight time from Chicago to LA was/is around 50 hours while the best passenger time was 39.5 hours. The Santa Fe could, and did with the "Super C", put freight over the route in less than 40 hours. They found out there wasn't much of a market for doing that expensive thing.
To move passenger trains at their higher speeds simply requires more power. That's an expense and the determining factor is whether the expense can be covered by what is charged to the customer. One reason long distance passenger trains are hopelessly uneconomic is that you can't charge enough to cover the cost of running them at the necessary higher speeds. Aircraft do it more efficiently and save much more time.
The best example comes from the Sea-Land SL-7 class container ships. These vessels could flat out move. They could sustain about 33 knots and legend is that the first Atlantic crossing of a SL-7 was intentionally slowed down so as not to ebarrass Cunard with their then new QE2. (Didn't want the cargo ship beating the time of a new passenger liner.)
The SL-7s almost destroyed Sea-Land. They couldn't charge enough to cover the cost of providing the extra speed. Container ships move around the world at about 22 - 23 knots and anything more than that is a waste of money. Sea-Land escaped its very big mistake by unloading the SL-7s to the Department of Defense which keeps the ships in reserve to move heavy Army units (think tanks) to where they may need to go. (Kind of a 1970's era bail out.)
So anyway, Amtrak trains have a lot of power so they can run fast. This helps make them money loosers. A 40 MPH terminal to terminal intermodal freight schedule will do just fine and get the vast majority of the freight off the highway. A 40 MPH passenger schedule is a dud.
That's one reason why rail freight makes economic sense and long distance rail passenger doesn't.
wjstix Part of it is providing HEP (head-end power). IIRC Amtrak's rule of thumb is one engine for every five cars. Remember everything in the passenger cars works from the engine's electrical power - lights, A/C, heat, ovens in the dining car, etc.
I have always heard that Amtrak's rule of thumb is one engine for every seven cars. That may work on most LD trains, but what about the Auto Train? It has two engines and 16 cars.
Will
I've heard of something like that too. In the early 2000s I remembered seeing mainly one P42 on either the Silver Meteor or Silver Star trains followed by 11-13 passenger cars. Two engines were only common on the Auto Train and the Sunset Limited, but I did see two engines on the Silver Meteor one time in 2001 I believe. I wonder why they run two engines now. I think the rules changed or something like that.
The Auto Train makes only a single stop for a crew change, The Silver Star and Silver Meteor make multiple stops and so need better acceleration. You will find that even with their stops the Star and Meteor cover the same distance in less time. In the West two units are the minimum, three for the Southwest Chief over Raton and Glorieta Passes. Two locomotives can get the Chief over the passes only by cutting off the power to the rest of the train proactively (before they start up the grade) and both units better be in good condition.
greyhounds So anyway, Amtrak trains have a lot of power so they can run fast. This helps make them money loosers. A 40 MPH terminal to terminal intermodal freight schedule will do just fine and get the vast majority of the freight off the highway. A 40 MPH passenger schedule is a dud.
IIRC, the majority of the cost of running an LD passenger train is labor, not fuel. There is a trade-off in reducing labor costs by running the train faster and the increased morive power and fuel costs, but I'd suspect that the cross-over point is higher than what is achievable on most lines in the US. The ROW, track and signaling could be upgraded to permit higher speeds, but the traffic would not come close to justifying the costs involved.
FWIW, the Iowa class ships needed 212,000 HP to reach 33 knots (about 3.5 HP/ton), where a train could easily beat 33 knots (38 MPH) with 1HP/ton.
- Erik
It has discussed the extra HP as being a waste of resources. But twice the HP on a given train is not twice as costly.
1. Crew time (Engineer & Conductor) either being able to make a longer run or not on duty so long as to go on overtime. That saves on total number of crews and the overhead of benefits.
2. For a given run you will not need twice as many locos since the trains can complete the runs faster by accelerating faster and climbing hills faster.
3. As an example BNSF intermodal haulage trains with 3 locos accelerate much faster out of our siding than same length UPs with 2 locos. (approximately same length)
4. Fuel consumption is greater with higher speeds as doubling speed should require 4 times the fuel.
5. Per diem / car hire ==. Especially intermodals almost all trains use TTX cars (however BNSF does use some of their own ) which I believe are subject to an hourly charge?. But BNSF would not need as many of their own or get as many TTXs) So if your operation requires X number of cars at a lower speed then you only require maybe 2/3X cars at a higher speed?
6. Fluidity is important,. The occasional slow train for whatever reason really gums up the works and so all trains that can maintain a good speed is important.
I wonder what would be the cost factors for rail travel if railways were maintained by the government, as are U.S. and Interstate highways? Truck/bus/airline travel is to/from federal-maintained airports, or upon federal-maintained roads and highways. Taxes and fees imposed are insufficient to cover upkeep. The railroads still are being forced to do their own road maintenance, AND pay fees, yet other transportation is subsidized ! Small wonder rail isn't cheaper than air travel !
mogul264 I wonder what would be the cost factors for rail travel if railways were maintained by the government, as are U.S. and Interstate highways? Truck/bus/airline travel is to/from federal-maintained airports, or upon federal-maintained roads and highways. Taxes and fees imposed are insufficient to cover upkeep. The railroads still are being forced to do their own road maintenance, AND pay fees, yet other transportation is subsidized ! Small wonder rail isn't cheaper than air travel !
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
And yet, European countries are able to subsidize their rail systems with other-than-auto fuel taxes, I believe, keeping rail travel costs lower. European autos travel MUCH less distances than the U.S., and as fuel is very costly, their average MPG is higher to use LESS fuel, so tax revenues MUST come from elsewhere. Also, European rail coverage is much better, area-wise, than the U.S., except perhaps the Northeast.
erikem greyhounds: So anyway, Amtrak trains have a lot of power so they can run fast. This helps make them money loosers. A 40 MPH terminal to terminal intermodal freight schedule will do just fine and get the vast majority of the freight off the highway. A 40 MPH passenger schedule is a dud. IIRC, the majority of the cost of running an LD passenger train is labor, not fuel. There is a trade-off in reducing labor costs by running the train faster and the increased morive power and fuel costs, but I'd suspect that the cross-over point is higher than what is achievable on most lines in the US. The ROW, track and signaling could be upgraded to permit higher speeds, but the traffic would not come close to justifying the costs involved. FWIW, the Iowa class ships needed 212,000 HP to reach 33 knots (about 3.5 HP/ton), where a train could easily beat 33 knots (38 MPH) with 1HP/ton. - Erik
greyhounds: So anyway, Amtrak trains have a lot of power so they can run fast. This helps make them money loosers. A 40 MPH terminal to terminal intermodal freight schedule will do just fine and get the vast majority of the freight off the highway. A 40 MPH passenger schedule is a dud.
Oh sure.
Once you turn a train into a hotel with beds, a restaurant, and a lounge it gets real expensive. (Labor cost.) But in my own defense I didn't say the cost of the extra power made the LD passenger trains money loosers, I said the cost of the extra power helped make them money loosers. And it does.
The Iowas were 1940's technology and powered with steam. If I understand correctly there are two of them still on the Navy's reserve roster and the Navy hates that. Congress will not allow the last two Iowas to be put to sleep. Container ships move around the world at about 67% of the speed the Iowas could do. The reason these container ships, almost 70 years later, don't go faster is not because the technology is not avaialble. The reason the modern ships go slower is that the higher speed is not economical. Pure speed is not the objective. Efficient, economical transportation is the objective.
I am of the opinion that there is an economic maximum speed for any transportation technology. In addition to the SL-7 economic failure, we have the Concord SST. Another dud. It could move people very rapidly, but the airlines operating it could not charge enough to cover the extra cost of the speed. The technology is available but it cost too much.
It is entirely possible to build tracks and trains to run on them that operate very fast. It's just not worth it.
greyhounds erikem: greyhounds: So anyway, Amtrak trains have a lot of power so they can run fast. This helps make them money loosers. A 40 MPH terminal to terminal intermodal freight schedule will do just fine and get the vast majority of the freight off the highway. A 40 MPH passenger schedule is a dud. IIRC, the majority of the cost of running an LD passenger train is labor, not fuel. There is a trade-off in reducing labor costs by running the train faster and the increased morive power and fuel costs, but I'd suspect that the cross-over point is higher than what is achievable on most lines in the US. The ROW, track and signaling could be upgraded to permit higher speeds, but the traffic would not come close to justifying the costs involved. FWIW, the Iowa class ships needed 212,000 HP to reach 33 knots (about 3.5 HP/ton), where a train could easily beat 33 knots (38 MPH) with 1HP/ton. - Erik Oh sure. Once you turn a train into a hotel with beds, a restaurant, and a lounge it gets real expensive. (Labor cost.) But in my own defense I didn't say the cost of the extra power made the LD passenger trains money loosers, I said the cost of the extra power helped make them money loosers. And it does. The Iowas were 1940's technology and powered with steam. If I understand correctly there are two of them still on the Navy's reserve roster and the Navy hates that. Congress will not allow the last two Iowas to be put to sleep. Container ships move around the world at about 67% of the speed the Iowas could do. The reason these container ships, almost 70 years later, don't go faster is not because the technology is not avaialble. The reason the modern ships go slower is that the higher speed is not economical. Pure speed is not the objective. Efficient, economical transportation is the objective. I am of the opinion that there is an economic maximum speed for any transportation technology. In addition to the SL-7 economic failure, we have the Concord SST. Another dud. It could move people very rapidly, but the airlines operating it could not charge enough to cover the extra cost of the speed. The technology is available but it cost too much. It is entirely possible to build tracks and trains to run on them that operate very fast. It's just not worth it.
erikem: greyhounds: So anyway, Amtrak trains have a lot of power so they can run fast. This helps make them money loosers. A 40 MPH terminal to terminal intermodal freight schedule will do just fine and get the vast majority of the freight off the highway. A 40 MPH passenger schedule is a dud. IIRC, the majority of the cost of running an LD passenger train is labor, not fuel. There is a trade-off in reducing labor costs by running the train faster and the increased morive power and fuel costs, but I'd suspect that the cross-over point is higher than what is achievable on most lines in the US. The ROW, track and signaling could be upgraded to permit higher speeds, but the traffic would not come close to justifying the costs involved. FWIW, the Iowa class ships needed 212,000 HP to reach 33 knots (about 3.5 HP/ton), where a train could easily beat 33 knots (38 MPH) with 1HP/ton. - Erik
O.T but the Iowa and Wisconsin were finally removed from the Navy's roster. There is however, a law that states that whichever group "adopts" them as museam ships must keep them in decent condition, in case the Navy ever wants to reactivate them (which,in relity, is about as likely as UP returning the remaining Big boys to revenue service)..
http://www.mesotheliomaweb.org/iowaclass.htm
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
greyhounds The Iowas were 1940's technology and powered with steam. If I understand correctly there are two of them still on the Navy's reserve roster and the Navy hates that. Congress will not allow the last two Iowas to be put to sleep. Container ships move around the world at about 67% of the speed the Iowas could do. The reason these container ships, almost 70 years later, don't go faster is not because the technology is not avaialble. The reason the modern ships go slower is that the higher speed is not economical. Pure speed is not the objective. Efficient, economical transportation is the objective.
I brought up the example of the Iowa's as they had the same top speed as the SL-7's and thus should have similar power to weight ratios (weight for the ship, not the machinery). The Nimitz class carriers also have about the same top speed, but I don't have their weight and power memorized as well as I do for the Iowa's. The main point is that ships are less fuel efficient than trains when speeds go above 20 or so MPH. The issue with ships is that wave drag gets out of hand when approaching hull speed, whereas the drag rise for freight trains starts at a much higher speed.
Your comment about the Concord SST is valid, the nature of Mach 2.2 flight makes it far less fuel efficient than flying at Mach 0.8. On the other hand, you also don't see much desire to further improve efficiency by dropping speed to Mach 0.6.
There are times when nothing does beat a 16inch Rifle hitting a bunker on the beach. Trust me Iran would Not be doiung half the crap they are doing NOW if we parked one of the Iowas in the Persian Gulf think of the Damage she could do just to the Docks for the Fleet or to the anything in range for 16inch guns. Then throw in her Longerrang stuff and you have a big problem. The thing is when we bring a Carrier into te Gulf they can not manuver and have to be closely gaurded.
edbenton There are times when nothing does beat a 16inch Rifle hitting a bunker on the beach. Trust me Iran would Not be doiung half the crap they are doing NOW if we parked one of the Iowas in the Persian Gulf think of the Damage she could do just to the Docks for the Fleet or to the anything in range for 16inch guns. Then throw in her Longerrang stuff and you have a big problem. The thing is when we bring a Carrier into te Gulf they can not manuver and have to be closely gaurded.
...We are way off topic here but the 16 inch gun issue is the "bring back steam" argument of many military discussion forums I visit. Why anyone would think in 2010 that a salvo of 16 inch shells is scarier to a potential enemy than 2000 lb. GPS guided JDAM smart bombs raining down from the sky or a wave of Tomahawk land attack missiles fired from submarine or surface vessels is a little beyond me.....
And don't get me wrong,I love Battleships, I pass the USS Massachusetts many days on my way to work and the USS Wisconsin (Iowa class) was in mothballs near where I live up until very recently..
I here you on that one. Most Nations Knew that the reason they are still on the Map back when Regan was the President was this. He let them be on the Map. We as a Nation have more Carriers than the Rest of the World Combined the only other Nation that even has anything like ours is the French and it is 1/2 the size or in Locomotive terms it is a GP-38 compared to aour GEVO44AC's. The Nimitz Class Carriers all weigh over 92,000 Tons Displacement and have a Flank speed of close to 40 Knots. Sad part is they can out run all their Escorts except the Aleigh Burke Destoryers Kept supplied with UNREP they can theorectically stay at sea forever barring a major engineering failure. Their 2 PWR reactors can produce close to 330K Shaft Horsepower for the 4 shafts that drive her.
I like to think of the old Iowa class BB's as the best we ever Built. The Proposed Montana class would have made the Iowa class Turn tail and run home to Momma. The Montana class as Proposed were the Big Boys of Battleships. 4 Triple 16 inch gunned Main Turrets with 32 Dual Turrets IIRC that book I read were 6 Inch then they had another 20 5 inch guns with 120 AA guns. All that on a Battleship that could do 32 Knots. We stopped construction of the class in 1942 when they realized the Ships would not be finished before WW2 ended.
edbenton I like to think of the old Iowa class BB's as the best we ever Built. The Proposed Montana class would have made the Iowa class Turn tail and run home to Momma. The Montana class as Proposed were the Big Boys of Battleships. 4 Triple 16 inch gunned Main Turrets with 32 Dual Turrets IIRC that book I read were 6 Inch then they had another 20 5 inch guns with 120 AA guns. All that on a Battleship that could do 32 Knots. We stopped construction of the class in 1942 when they realized the Ships would not be finished before WW2 ended.
You are right and this is totally off-topic, but here are some corrected details. 1. Because the Montana-class top speed was much slower than Iowa-class BBs, only 27 kn compared to Iowas' 33 kn., the proposed new ships could not have kept up with the Essex carriers and Iowas being built. They were actually an outdated weapons system in the age of the aircraft carrier. Hence work was suspended after Midway in 1942 , before any keels were ever laid, and canceled in 1943 because of that realization, not because they wouldn't be finished in time. In 1943, no one knew when the Pacific war would end, certainly not by 1945. 2. Along with the 12 16" guns in four turrets (not triples, each gun was independent), there was secondary armament of 5" guns in 10 dual turrets. Anti-aircraft guns were a combination of 20mm and 40mm weapons.
C&NW, CA&E, MILW, CGW and IC fan
Greyhound,
Sealand had seven or eight SL7 class container ships with one group running between Europe and the US east coast, and the second group running between the far east and the US west coast. At 120,000 shaft horse power (on two shafts) they were the highest powered, non-passenger commercial ships afloat at the time.
I was fortunate enough to get aboard one of the west coast ships when she was in drydock in Esquimalt, BC. Talking to her Chief Engineer and the Port Engineer for Sealand, I was told that the maximum recorded speed was 32.5 knots, achieved in the English Channel. An article about them that appeared in Marine Engineer Log magazine stated that a reduction in speed from 32 to 28 knots would save some 640 tons of fuel per day. The ship that I visited had made the run up from California to BC for dry docking at 22 knots with one shaft seized! The fuel consumption on that leg of her voyage would have been rather high I think.
They were very fine lined vessels in order to achieve their high speed which meant that they could not carry as many boxes as a more conventional container ship. This must have had a big impact on their profitability in addition to their high fuel costs. At that time the average container ship was steaming at 25 knots. Now days, with slow steaming to save fuel, most container ships are running at under 20 knots.
Apparently seizes shafts were fairly common for these ships, a problem that I have been told persists to this day. Seems selling them to the US Navy was a good thing for Sealand, but maybe not so good for the Navy.
Mike Ball
Sometimes it's for no other reason than to move excess locomotives from one area to where they're most needed.
One thing you have to remember about passenger locomotives is the gear ratio.They are geared for high speed running.They are similar to the steam locomotives in the sense of starting a 10 speed bicycle in high gear.They may have a lot of horsepower but they would probably suck at starting a heavy freight train.Switching freight cars in a yard using a passenger locomotive would be almost useless and very time consuming.
It takes a enormous amount of power to pull a train at 79 and that's where the gear ratio starts to kick in.Passenger locomotives could probably out pull any freight locomotive ton per ton once you were past 50(think of putting your transmission into 5th gear)while the freight locomotive is still stuck in(4th and can't go any higher).Freight locomotives pull hard at slow speeds and lose power fast at faster speeds.Passenger locomotives are weak at starting but pull harder at faster speeds.
Amtrak has more then enough power for most passenger trains with one locomotive.They nearly always have two locomotives on long distance trains because 1.they need a back up in case the lead unit is having problems and 2.they need extra power on hills where the high gear ratio is going to reduce pulling power dramatically.
I also don't know what people are talking about when they are saying the passenger cars electrical is using the locomotives engine for power it and that is using horsepower.I have worked on many locomotives and I have never heard of a locomotives engine supplying electrical for the passenger cars.Every passenger locomotive I have ever seen has a HEP(Head End Power)in the rear of the locomotive which is a small 6 cylinder diesel engine that turns a generator to supply the electricity.If a locomotive does not have a HEP then it is typically pulling another car behind it that has a HEP unit inside it.
Here is a photograph of the Santa Fe freight train called the "Super C"
Super C
It was run on a schedule similar to today's Southwest Chief. If you look closely you will see that the short train of all trailers on flat cars is powered by 4 SD45-2s. The train weight is probably twice what the Southwest Chief weighs and so it needs almost twice the horsepower to maintain a similar schedule.
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