Even if the cop dosn't show he can hold over for trial where the officer can be there to testify.
I have only seen this done once in traffic court. It was a school bus stop sign ticket.
I hope and wish you the best with the ticket! I think it sucks that the courts don't really care at all what happened if it has to do with a bus.
With all that said, I would still go to court and give it a shot! What you have posted here and the diagram you did you do have a chance!!
BTW Judges don't like it much when people bring lawyers in to traffic court.
Good luck once again.