Here is a three dimensional drawing of a good accessible toilet.
1. A good layout will save space. However, there is a minimum space requirement for a good accessible toilet. As motorised wheelchairs become more common, toilet size should be bigger to accommodate motorised wheelchair users.
2. There must be big enough for wheelchair to maneuver inside.
3. The door should not obstruct wheelchair from maneuvering inside the toilet.
4. There must be space for side-transfer.
I have made the two drawings below very big so that you can see the measurements clearly.