Los Banos, California Roadblocks
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.
This checkpoint has a turnoff, but it is after the cone pattern begins, so most do not avail themselves of it. Officer in charge says the CHP no longer chases vehicles that turn off to avoid the roadblock. A local commander told me, after spouting the party line, when I asked him his personal opinion– "Complete waste of time."