Police may also set up roadblocks and stop drivers without particularized reasonable suspicion that the stopped individual is engaged in criminal activity, so long as the plan for the stop is applied neutrally, for instance, driving while intoxicated - so long as all vehicles are stopped or every third vehicle is stopped, or some other reasonably neutral policy is applied for stopping vehicles. Note that some states also impose additional notice requirements for roadblocks, such as appropriate signage and/or flashing blue or red lights.