This was set up on a weeknight, and tge only apparent warning was a sidewalk sign not visible to backed up cars until they were on top of it. When I saw it, I attempted to turn right, but was promptly stopped by the chase vehicle, who claimed I didn’t signal. The checkpoint sign on the sidewalk was in the direct line of sight where his chase vehicle was parked, so he could not see my signal. From what I later observed, Los Banos PD was stopping most vehicles that attempted to turn off.