Amazing idea! We've been talking about beacon technology in class, but mostly about increasing sales for stores. This idea combines existing technology with public welfare, which is very creative and unique.
I see there is an challenge on convincing private bus owners, but there might be ways to incentivize them besides the inspiration of helping visually impaired people. For instance, coupons also for bus owners, depends on how many devices sensed by their bus? Also, are there possibilities to get government/corporate funds?
All in all, great idea! Keep working on it and it'll make great impact!