1 foot rise per twelve feet of run. with a minimum of five feet between railings accessible from thirty inches above the ramp and another handrail at the conventional 3 and a hlaf feet above the ramp. I'm an architect major, this is like second language to me.

I know where I live it is 1"of slope for every 2 feet of travel. I am not sure if it is the same for all cities. Good luck and hope this helps

Here are the federal ADA specs for pretty much everything related to building accessibility: http://www.access-board.gov/adaag/html/adaag.htm The maximum slope allowed is 1:12. As an occasional wheelchair user in good shape, it is OK for me, but I can attest that this is much too steep for MANY people. 1:16 or 1:20 is much preferred. Some people really can't get a ramp steeper than 1:20 by themselves. Don't forget that landings are really important. You have to have a level landing at the top and the bottom of the ramp. They are essential if the ramp makes a turn. Landing have to be perfectly level and take up at least five feet. Personally, I think that landings in front of doors should be at least 6 feet long and wide, because it can be really hard opening a door without risk of rolling backward, and it is much easier if someone is pushing if they have room to stand on the level and also to walk around the safely parked chair and open the door. Calculate carefully if you are planning to build a ramp. Because of the landings, the actual linear length of a ramp is considerably more than the ratioa might lead you to believe.