My daughter got involved with a local group that does therapy for disabled and emotionally challenged children. (She was actually one of the first group of kids in the category for the pilot program and is moving up to Jr. Student Helper!)

The group has only been going a year and a half and they are moving along into the next phase of their growth and now need a special outdoor ramp constructed for allowing people in wheel chairs to ascend up to the level of the therapy horses and mount them to ride.

We have been looking at the A.D.A requirements and trying to figure out how to calculate a gentle slope angle so we can design and create a materials list that we will be using to gather donations for. The ramp will have to be in two levels with a short landing in between. I don't have any of the dimensions of height yet but have seen other examples. The examples typically have a rise from ground level to a small pad to turn 180* and rise to the next level where they can be assisted to mount onto a horse.

My thoughts are to build the entire ramps in aluminum, (since it will be outdoors and need to be semi-portable), and coat the decking with Herculiner truck bed coating, so that it will provide non-skid grip even in damp conditions. There will also be an accompanying hand rail system but that will be tubular and easy to construct as part of the ramps.

My question is: Has anyone ever done something like this and could provide me some dimensions and / or ideas and images?

Thank you in advance for you replies!