Since you don’t mention your scale it is hard to state exactly what fits in your situation. One method is to determine the grade (or track inclination) you want to use. A 1% grade would be a SCALE one foot rise over 100 SCALE feet of track. A 2% grade would be a scale two foot rise over 100 scale feet and so on. A 3 to 3.5% grade is just about as steep as you can get before the pulling power of your model locomotives becomes nonexistent unless you are running Shay or Climax type locos.

Diesel loco models GENERALLY have better pulling power than steam although steam locos equipped with tires (yes, you read it right) perform better than with no tires at all.

Note that an incline on a curved track section will have MORE friction so you’ll find that you can’t pull as many cars as you would on a straight incline of the same grade regardless of motive power.

Finally, the quality and maintenance of the freight & passenger trucks you have on your equipment plays a part in loco pulling power on ANY surface be it curved, flat or inclined.

Throw together a mock track setup as an initial check before you start any construction or changes. I would suggest setting up various grades and/or situations that would mimic your future track plan’s features and see what you equipment can handle. I think you’ll be surprised how much your equipment’s pulling power falls off once an incline has been added to the mix

Hope this helps,

Geof