Couple of suggestions: In my Hospital our President welcomes hearing from employees-last year he wrote a one-page apology memo to employees because on an "ice cream" social day, there were no Ben & Jerry Cherry Garcia ice cream bars at the main campus. I know he would respond positively to your problem. We have at one of our buildings a reserved parking place for a wheelchair-bound employee right at the door specifically for him.
Second, if there is a Risk Management department they might be able to help. They want to make sure employees and clients are physically safe and that they not pay out for slip and fall claims. You might want to contact them as it could have a direct impact on avoiding a claim and an increase in premiums.

I had my ADA meeting this week. It could be considered an initial dialogue; they made no committments, but it was obvious to me that they need to read the ADA regulations; their responses were very weak and I don't think would hold up if I lodged a complaint. But I'm just going to take it slowly and not be threatening or they'll find some other reason to fire me, but they are on notice and I'm documenting everything.