I know nothing of trains, but I do know there are people out there for whom they are almost a religion. If I’m asking a stupid question, I apologize and only offer my ignorance as an excuse.

I’ve always wondered what the reasoning is behind attaching more than one locomotive to a train of railcars. Obviously, it’s so they can haul more cars, but why not just have each locomotive haul its load separately. Is it to save on labor? Is only one of the locomotives staffed, leaving the rest to be controlled from that engine?

If this is the case, is there a limit to how long a train can be? Could someone string together 30 miles of train if they had enough locomotives? Could you staff it with the same number of people needed on a single engine train? Is there a world record for this sort of thing? What are the limits set forth by whatever agency regulates such things?

I did a search to see if I could come up with something but the findings were pretty small. My guess is that the limitation on the number of cars has to do with scheduling of stops; as in, who are they delivering to, what other trains of how many cars are running on the same lines, etc. There’s probably some physics reasons too: friction, limitations of diesal engines, time to get up to a “running” speed, stopping times, etc but, honestly, those are beyond my ken. I have a friend who is training to be an engineer, a life-long dream of his, and he says a lot of the train “driving” is computerized. I think he said there’s typically only about a staff of 2-3 per train. I love to watch a train go by. Their size always amazes me! Hope someone else can help with more than my measly amount!

PB, I think that the dual locomotives are used on cross country hauls. The trains need more power to get the load over the Rockies or other mountains. On the down slope they turn off one of the engines. They also may attach several engines to re-route part of the train during long hauls to different destinations.

I lived about 50 feet from a very busy set of train tracks for five years. Virtually all trains (that passed us) have more than one locomotive – usually 2 to 4. In this part of the country, they ain’t going over the continental divide, either.

I was also surprised to notice that there are still hoboes riding the rails. I noticed men on the backs of RR cars on several occasions.

“Owls will deafen us with their incessant hooting!” W. Smithers

This is really reaching back into my memory of junior high school, but IIRC the Canadian Pacific and Canadian National Railroads use engines in tandem sets for extra long or extra heavy trains, or for those making the run over the Rockies.

I recall seeing as many as FOUR engines at the front of a big “unit train” going through the Rockies as a kid (about 1968). I think the train was well over 100 cars long, with grain cars the only type of rolling stock.

I have more recently seen a pair of engines at the front of a loooong unit train of coal cars, with a second pair of engines as “relief engines” about half-way back down the train.

When train engines are strung together, they can all be controlled from the lead engine. So a double-header train means one less engineer than two shorter trains. I’ve never seen relief engines like Rodd described, but then Michigan’s landscape isn’t exactly difficult to cross. Around here, the really long trains are the ones that have auto racks as the primary rolling stock. You typically see two or three GM-EMD diesels pulling as many as a hundred racks.

“I had a feeling that in Hell there would be mushrooms.” -The Secret of Monkey Island

Pulling the mass of a long, heavy train through any terrain places undo strain (hey, that rythmes) on the couplings moreso than the lead locomotive. To balance the load, crewless “slave” locomotives are placed, usually toward the center, and are radio-controlled to the lead locomotive.

As for the record: In 1989 in South Africa’s Sishen-Saldanha ore line, a 660-car train
grossing 71,600 tons and 4.47 miles long was run from end to end of the route. Power was furnished by five 5,025-horsepower electric locomotives at the front, four more inserted after the 470th freight car, and at the rear, to avoid overtaxing the traction current
supply system, seven 2,900-horsepower diesel locomotives.

Two things:

Rhymes, not rythmes. Duh!


So size does matter.

I have a question about an expression, used at the end of the last verse of “City of New Orleans,” written by Steve Goodman: “disappearing railroad blues.” Of course, Goodman is no longer around to tell us where this expression came from. How did it originate? Except for this song’s lyrics, I have seen it nowhere else except in the first Straight Dope book, wherein Cecil used it at the end of his discussion of “Phoebe Snow.” Someone please answer this for me. Thanks. :slight_smile:

“Disappearing railroad blues” is a comment on a vanishing way of life. I think City of New Orleans was probably writen in the 50s when the airliner and automobile were supplanting the train as the principle means of transportation. “Don’t you know me? I’m your native son.” is a plea to America not to forget a rapidly fading way of life.

In other words, the song is probably the source Cecil took it from.

Sly - It never occured to me that the couplings would have a limit to what they could handle. Putting engines in the middle of the train makes sense now.

The train they call the City of New Orleans makes the trip from Chicago to New Orleans fairly regularly according to the Amtrak web-site <>.
The schedule says the train “City of New Orleans” leaves Chicago at 8PM for New Orleans and returns at 9:20AM the next day.


A locomotive machinist told me of another reason for the engines in the middle of trains. The brakes on these trains are pneumatic. The air pressure is produced by a compressor in the locomotive. when a train reaches a certain length (150-200 cars), the compressor cannot provide enough volume to adequately apply all the brakes. So another engine is added in the middle.

Or it could be simply to simplify swithing later when the train is split for different destinations. (WAG)

Another 'limitation on the length of a train is the amount of time it takes to pass a grade crossing. At least in Texas there is a time limit on how long a train can block a crossing with out moving or while switching. The limit for a moving train is longer. I don’t know what the limit is and the regulation seems to be more honered in the breach.
Now a question. Years ago I read in Popular Machanics, an article about a regularly running produce train that was extremly heavy and extremly fast.If I remember correctly just before it crossed the Sierras extra engines were added for the climb. Then on the down hill side the electric motors were disconnected from the generators but not the drive train, and allowed to run as generators,(where the power went I don’t remember)thus acting as brakes.
The train coasted down hill and across Arizona befor the engines were re-engaged.
Or maybe I hallucinated that anybody ever heard of such a thing?

To pmh: I’ll have to ask a railroader about that one. I never heard of anyone “swithing” before. :slight_smile:
On to a more serious question: During the heyday of passenger train travel, you would have to chaged trains–even stations in some cases–on an east-west trip, of any length, in Chicago, St. Louis, or New Orleans. In fact, an ad appeared with this bold statement as a banner, over a picture of a family gawking at a languid pig in a cattle car:
“A Hog Can Cross the Country Without Changing Trains–but YOU can’t!”
I asked some people I know about this; one said railroads deliberately did this to make train travelers pay more; another claimed it was because the “Superliners” used in the West were too big for Eastern railroad tunnels. Any answers from the Teeming Millions?

Excuse me: “Have to change trains.”

“A Hog Can Cross the Country Without Changing Trains–but YOU can’t!”

Actually, a pig (or any freight) would stay in the same car. The car would be switched to the appropiate train along the way to it’s destination. That’s what’s happening when you have to wait hours at a RR crossing as a train plods back and forth.
BTW; Freight always has priorty over passenger service.
Also; US rail passenger service really sucks, due in large part to lobbying by the airline industry.

ManGeorge is correct. The truth is, it was/is much more profitable for rail operators to transport livestock and other freight than people. Pigs and cars don’t complain when you pack them in like sardines. Railroads are set up in (about) thirty-mile blocks (longer in remote areas) and no two trains can occupy the same block. If a scheduler has to choose between a passenger train and freight, he’d opt for the freight. Money talks. People, er, wait.

For the record, it was also the train involved in the nasty ‘train hits a truck and derails - lot of people hurt, some killed’ incident a few months back south of Kankakee.

“I guess it is possible for one person to make a difference, although most of the time they probably shouldn’t.”