This app was mentioned in 3 comments, with an average of 2.67 upvotes
It exists already ;)
https://play.google.com/store/apps/details?id=org.wheelmap.android.online (Also iOS and browser)
But project like this are dependending on a activ community. In Germany it's pretty good in bigger city's.
As you can see below there are already some applications(both on Android/MAC) Wheelmap is the most popular one with 10.000-50.000 downloads. Maybe you can use one of those apps below instead of building one(or a whole website) yourself.
Wheelmap-> https://play.google.com/store/apps/details?id=org.wheelmap.android.online
On Wheels-> https://play.google.com/store/apps/details?id=com.onwheelsapp.onwheels
Wheelmate-> https://play.google.com/store/apps/details?id=com.novasa.wheelmate
MyHandicap-> https://play.google.com/store/apps/details?id=uge.myhandicap
EsAcessible-> https://play.google.com/store/apps/details?id=com.esaccesibleapp.gratis