simple story:

-someone t-bones his driver side door
-he says he had a green light
-lady that had him said it was a red light
-cop gives him a ticket for running a red light
-goes to court - surprise cop wants to wait for a witness to show up
-he doesn't know there's another witness
-that's where the story ends - continuance on the case
-he wants a witness to back up his side if anyone saw the wreck

if they didn't tell you there was another witness, I believe that is case to dismiss the witness. I'm pretty sure traffic court is like regular court. They need to tell you they have witnesses (discovery rule) so you have time to prepare for them before court comes up, or at least give your side a copy of the witness's deposition