What factors must be considered in determining whether or not to close a motor vehicle checkpoint when traffic is light?

Primary consideration must be given to maintaining safety for motorists and officers. Proper lighting, warning signs and signals, and clearly identifiable official vehicles and personnel are necessary to minimize the risk of [43 Cal.3d 1343] danger to motorists and police. (Cf. Jones v. State (Fla.Dist.Ct.App.1984) 459 So.2d 1068, 1079.) The checkpoint should be operated only when traffic volume allows the operation to be conducted safely. Screening procedures may at times be altered consistent with traffic volume, such that, for example, every car might be stopped when traffic is light, but if traffic began to back up, a different neutral formula might be applied, such as every fifth or tenth car, or operations might be temporarily suspended until traffic volume permitted resumption of safe checkpoint operation.