reinforcements of the centuries-old common law negligence doctrine as specifically applied to vehicular speed. California Vehicle Code section 22350 is typical; it states that "No person shall drive a vehicle upon a highway at a speed greater than is reasonable ... and in no event at a speed which endangers the safety of persons or property". Speed limits in California are mandated by statute to be set: (1) at or below the 85th percentile operating speed; as determined by a traffic and engineering survey—this is the speed that no more than 15% of traffic exceeds; or (2) the prima facie limits mandated when certain criteria are met as described in the vehicle code. These criteria include school zone, alleyway, and residential area. If the 85th percentile operating speed as measured by a Traffic and Engineering Survey exceeds the design speed, compulsory legal protection is given to that speed—even if it is unsafe with regard to certain technical aspects such as sight distance. This speed creep may continue until the 85th percentile operating speed is comparable to speed psychologically perceived as uncomfortably hazardous. The theory behind California's 85th percentile statute is that, as a policy, most of the electorate should be seen as lawful, and limits must be practical to enforce. However, there are some circumstances where motorists do not tend to process all the risks involved, and as a mass choose a poor 85th percentile speed. This rule in substance is a process for voting the speed limit by driving; and in contrast to delegating the speed limit to an engineering expert. The numerical limit set by Caltrans engineers for speed limit signs, generally found on all non-controlled-access routes, is considered a presumptive maximum "reasonable and prudent" speed. Many speed limit signs are identified as "maximum speed", usually when the limit is or more. When the National Maximum Speed Law was enacted, California was forced to create a new legal signage category, "Maximum Speed", to indicate to drivers that the Basic Speed Law did not apply for speeds over the federally mandated speed cap; rather, it would be a violation to exceed the fixed maximum speed indicated on the sign, regardless of whether the driver's speed could be considered "reasonable and prudent". A driver can receive a traffic citation for violating the Basic Speed Law even if their speed is below the "maximum speed limit" if road, weather, or traffic