This would be a live application, so as new buildings and locations are built, the database needs to update continuously. Therefore, the application allows anyone to add data if they find an accessibility that is not in the database. This way, the application stays as updated as possible.
I would find this application successful if the community who needs daily accessibility find it useful and easy to use. Also, if it improves their daily lives and increases their efficiency in mobility, then this application has successfully done its job.