I saw this today when I was looking at a job.
You would think they would have made the slab fit the whole of the tray. In their defence, there are two 'sort of' handles at each side of the tray (inside), you can just about see them in the photo, they come level with the proposed slab, which means the slab would hit them.
Should they have cut the slab exactly the correct size of the manhole tray, and then cut some of the slab away to make room for these handles.
Hope that makes sense.