Site Selection — Planners should take into consideration the safety and visibility to oncoming motorists: Safety checkpoints cannot be of less public benefit than the behavior they are flying to displace, nor call they create more of a traffic hazard than the results of the driving behavior they are trying to modify. Planners should remember to select a site that allows officers to pull vehicles out of the traffic stream without causing significant subjective intrusion (flight to the drivers and/or creating a traffic backup). Furthermore, offices safety must be taken into account when deciding where to locate the checkpoint. Checkpoint locations should be selected in advance by officers other than those manning the checkpoint according to objective criteria that will maximize contact with DWIs, for example, locations with a high incidence of DWI-related fatalities, nighttime injuries or nighttime single vehicle crashes. If every vehicle is not to be stopped, the method used to determine which ones will be stopped must appear in the administrative order authorizing the use of the safety checkpoints.
Warning Devices — Special care should he taken to provide adequate warning to approaching motorists that a roadblock-type checkpoint has been established. Such notice can be accomplished with warning signs, flares and police cars with warning lights flashing. If possible, warning signs should he placed along the roadway well in advance of the checkpoint to alert motorists that they will be requited to stop. Signs should be placed to provide advance warning as to why motorists are being stopped, but at the same time should not give impaired motorists the opportunity to avoid the checkpoint.