Once you get to Redwood City to drop off the loaded cars there is already a set of cars on the track you are supposed to be on. Can't drop behind because you have to continue to San Francisco and you cannot go around and back in due to red signal. Did I miss something or is this a bug / glitch?
This is a bug. But you can complete it by routing yourself onto a parallel track and backing in. I was able to complete that service.