weight

[Anonymous]

are the weight restrctions for trains based upon the track capabilities or the contour of the land ?

[Anonymous]

Scott,

Weight limits for individual cars are based on track performance but the overall limit for the train is based on the running speed requirement which is related to engine pulling capacity and the contour and curvature of the track alignment.

This is a bit of a simplistic definition but I hope it gives you the answer you are looking for.

Ed

[CShaveRR]

Actually, weight limits for individual cars are based on the cars' trucks (bearing size, wheel diameter). The trucks determine the cars' gross rail load, which is any of about four or five different figures. The track structure is generally maintained to support cars of one of those gross rail loads (a few lines can't handle anything heavier than 70-ton cars (220000-pound GRL); most can handle 100-ton cars (263000), a lot have been upgraded to handle the new 110-ton category (286000), and a few heavy main lines can handle the relatively uncommon 125-ton cars (315000 pound gross rail load).

Train length may be governed somewhat by terrain (in extreme cases), but it's more likely to be determined by sheer physics...the forces on drawbars would eventually become prohibitive. And that's one reason distributed power is coming into play--you can move (and handle!) longer trains by putting the power at both ends (or the front and the middle) and easing some of that load. Braking is another consideration... distributed power can help there, too; electronic braking will eventually make longer trains handle better.
I guess there are certain territories over which longer trains don't handle as well, but it's more of a nuisance than a prohibition.

[Anonymous]

Thank You for the answers.I see the HEAVY container trains on the web and knowing they are coming from the west coast to Chicago,I wondered about the weight.

[Anonymous]

Well, as a structural engineer, I'm certain that I could design a truck to carry twice that load. But since it would tear up the rail, what would be the point. The limit for car capacity is the rail, not the trucks.

[CShaveRR]

True, if you designed a 250-ton truck, the track would have to be redesigned in some way to handle it. But by then you'd also have to redesign other freight car components to withstand that type of load (and to what purpose? the cars barely fit in the clearance plates now!).

[Anonymous]

What is the weight limitation per large container
and per rail trailer with 3 containers on it ?
That seems like a TON of weight. So,from LA to Chicago its only on certain rails that can handle the weight ?

[corwinda]

Which kind of container car? I see some double stack well cars marked '125T' but most would be less.

Also; container weight limits are more likely imposed by road weight restrictions than anything else. (In those cases where the container isn't full before reaching the weight limit.)

[Anonymous]

both, actually, along with the restriction on how hard you can pull on the coupler/drawbar before it fails. Another consideration is also bridges and their cooper (axle loading) ratings. If you are talking total train weight, the primary restriction is coupler/drawbar strength which can be negated through the use of distributed power. Theoretically you could, (using dp power) run an incredibly heavy train, however it would be so long that it would overwhelm all the facilities (yards,sidings, loading/unloading points). They have on occaision done this very thing in Australia, I have read about a test run where it was something like 500 cars, 30-40,000 tons, had several sets of dp's, etc. Currently on the UP, the norm for our heaviest trains is around 18,000 tons, 135 or so cars, dp power, coal train. I read some of the other replies where someone said something about heavy stack trains, actually these are relatively light for their lenght, generally you almost never see a stack train much over 7000 tons and that would be a pretty long stack train. If you are talking about heavy cars, then it is almost always bridge restrictions as far as the absolute max, now for everyday service the limiting factor is rail and tie condition. For example, the line I work (actually UP's system standard as well, with exceptions) has a max of 143tons/car with 2axle trucks. However, there are lot's of times where individual cars way over 143 tons come through (like turbines, cooling units, etc) but these cars are on 6,8 or more axle truck assemblies. Like I said before, the limiting factor in these heavy car's case is axle loading on the bridges, as well as the bridges absolute max loading for a given section.
Hope you found some of this helpful

[Anonymous]

Containers are bad of getting overloaded.Intermoadal trailers a lot of times have there loads shift and they will be overloaded on certin wheels.

[Anonymous]

Thank You to all who replied. It has answered an often thought of question. I live near the UP line that runs the coast route between LA and
Washington state.