Wheel Chair Ramps can be difficult to build. Unfortunately they are a little outside of our scope of work but here are a couple of general tips. Keep the ramp as wide as possible. you would like to have a usable area of at least three feet. Do soome research on ADA approved ramps. This will give you an idea of the slope. Finally, check with your building department to see if they have any specific requirements for wheelchair ramps.
Here are some links that might help you.
www.wheelchairramp.org
www.wheelchairramps.com
www.ada.gov
Deckman