Thank you for the guidance.  I think 7 or 8% will work.  Mine will also be going around the xmas tree.  The grandkids are coming from thanksgiving to January.  Since this is a temporary setup, I am not overly concerned with the extra load on the engines. 

Grampa Gary

I am planning a small tunnel on an indoor track, so it will be easy to lift it off for service.  I would like to keep it as low as possible in order to run another  track over the top.  What do you think the steepest grade would be that will work with four cars on?  I don't have a lot of length to make my elevation.   I don't think I can keep it under 4%

Gary

How much vertical clearance should I build into a tunnel?

Also, what is the steepest grade you would recommend?  Is there a grade standard?

Thanks

Gary

I am curious as to what material the track rails are formed from, and if they are steel, what is the plating used to protect them?

Are they suitable for use out doors?

Thank you,

Gary Klein