What is the maximum grade of a railroad track?

Question

How steep of a grade is designed into a railroad line?

Answer 1

The heaviest grades I operated on were found on the late, great Southern Pacific.

When working out of Roseville over the hill to Sparks, the ruling grade between Colfax and Emigrant Gap was 2.4%

I transferred to the Oregon Division in 1983 and, when working the now sort-lined Siskiyou Sub-division, the ruling grade was 3.1%.  Here, 900 tons per unit was the max, with a maximum of 2,700 trailing tons on the draw bar.  The trains were always at 7,200 tons, so we got a four unit road engine with a five unit helper.

Not to be argumentative, but the 2-8-8-4s of the Duluth, Messabe and Iron Range, Baldwin Class M-3, out did the UP Big Boys in the weight on drivers and tractive effort departments, as well as other key power producing points.  Alco publicized the Big Boys extensively, but Baldwin didn't put the DM&IR M-3 engines in the public eye.  

Here is how they stacked up in a side by side comparison:

Weight on drivers:

Alco Big Boy  =  540,000 lbs...Baldwin  =  560,257 lbs

Tractive effort:

Alco Big Boy  =  133,375 lbs....Baldwin  =  140,000 lbs

Wheelbase, engine and tender:

Alco Big Boy  =  117' 7".............Baldwin  =  113' 5&7/8"

Weight, total engine:

Alco Big Boy  =  762,000 lbs.... Baldwin  =  695,040 lbs

Boiler diameter:

Alco Big Boy  =  95"....................Baldwin  =  104"

Cylinders:

Alco Big Boy  =  23&3/4" x 32"...Baldwin  =  26" x 32"

Weight, engine and tender:

Alco Big Boy  =  1,104,200 lbs....Baldwin  =  1,131,675 lbs

Boiler pressure:

Alco Big Boy  =  300 psi...............Baldwin  =  240 psi

So, now that you know that the Baldwin M-3s were the true kings of drag freight operations, you can clean up betting against the Big Boy, and you'll have no shortage of takers.

I would recommend at least ten to one odds when the wager is made.

Answer 2

One of the steepest mainline grades in the U.S. was the Saluda Grade in North Carolina. For 3 long miles, coal trains had to battle tough grades, reaching 4.7%, and topping out at 5.1% at one point. In December 2001, NS suspended all operations over Saluda. They rerouted their coal trains and the few merchandisers over more efficient routes. Some of the track has been tore up, but maybe some day the line will become operable again.

Answer 3

Well, that depends.  There are specialized cog railroads (that evidently require cog equipped locomotives) that can reach extreme gradients, if I am not mistaken, the record is something like 48% (a railway in Switzerland).

For "normal" railway, the steepest slope is a function of what one is willing to put up with in terms of tractive effort and adhesive weight. Logging railroads can be a lot steeper than mainlines, where the cost of having enough locomotive power to haul a train is one of the things that must be considered.  That said, 6% is perhaps an upper limit for short lines, and 3.25% for mainlines.  Follow the link for a heated discussion of that very topic.

Answer 4

The 1942 model 4014 Big Boy train pulled 3600 ton of train cars loaded up a 1.55% grade at sherman hill. Put it this way, the train from the front to the rear of the tender was 132 ft long and weighed about 700,000 lbs and had over 6000 horse power.

It was the only engine that could pull that much weight up that steep of a grade. By far the greatest train ever to roam the tracks!!!                 Check it out at (Big Boy train) on the net