Maximum practical grade in N scale? - Model Railroader Magazine
The answer to this question is independent of scale:
It will vary with your specific engines, rolling stock, the amount you weight your cars and the relative friction in your trucks but as a guide you could use the information in John Armstrong's book, Track Planning for Realistic Operation. In his book he provides a graph indicating that with average trucks you will pull about 24% the tonnage on 4% grade you will over level track and 18% the tonnage on 5% grade. Free rolling trucks pay an even bigger price.
To put this in perspective (I run HO Scale) ...
An engine that pulls 24 cars on level track will pull about six cars on a 4% grade and five cars on a 5% grade. If you are fond of double and triple heading your trains and/or you don't use caboose then you may be happy with the results.
I wouldn't go with a grade this steep in plain view unless I was dilibrately constructing a helper service grade. If operations of this kind appeal to you then you can have a lot of fun. You could construct a siding at the summit and double the hill or provide a helper with sidings at each end. You can also indicate the entrance to the hill with permissive signals to prevent heavy freights from stalling on the hill. This is discussed in Mr. Armstrong's book (cited above) and in Bruce Chub's book, How to Operate your Model Railroad. I recommend both books if you don't have them already.
Good Luck. - Ed
