I am a C5-6 quad with both manual and power chair. Am a bd member of Parks and Trails NY and we have been involved in training volunteers to perform trail assessment.
Edge protection strips should be higher than 2/3 the height of a typical front wheel so that the wheel cant cross over the barrier without getting the user stuck or falling over.
Picnic tables: 50% seems like a reasonable number. Door tensioners should be adjusted for the least able and should be capable of being flung wider enabling the chair user time to clear the portal without having to hold the door with one hand.
Resting intervals: In the absence of a prescribed distance, 50 yds is probably a reasonable interval for an area of continuous slope.
Drainage: In areas that need slope for drainage, the high side should have adequate flat area so a chair would not tend to drift to one side. Otherwise, a slight crown makes for easier rolling.
Surface: In a wilderness setting, crusher run covered by stone dust gives a relatively smooth surface and is easily repaired (see surface of Erie Canalway trail). New construction may take a couple of years to “cure”, but is passable the first year.
Alan N. Vincent
Little Falls, NY 13365