California's speed laws can be found in the state Vehicle Code.
Section 22350 is the Basic Speed Law, which states that California
drivers may not drive faster than is "reasonable and prudent and in no
event at a speed which endangers the safety of persons or
property." How do you know what speed is "reasonable and
prudent?" Sections 22348 through 22413 of the Vehicle Code establish
"reasonable and prudent" speed limits for various types of roads. These
default speed limits are also known as prima facie speed limits. For
example, the maximum speed on most California highways is 65 miles per
hour. On a two-lane, undivided highway the speed limit drops to 55 mph.
The prima facie speed limit is 15 miles per hour in alleyways and
approaching blind intersections or railroad crossings. It's 25 miles
per hour in near schools or senior centers.
However, the prima facie speed limits can be altered as appropriate to
fit local conditions. This is usually done through an engineering and
traffic survey, where the speed that people naturally drive a
particular stretch of road is measured. The government generally tries
to set the speed based on the speed that 85% of drivers are traveling
at or below-the goal is to set a speed limit that is both safe and
comfortable for the majority of drivers. So, while it can be useful to
know the default speed limits listed above, it's more important to keep
an eye out for the posted speed limit signs.
It's also important to remember to adjust your speed based on
conditions such as weather and traffic. Posted speed limits are maximum
speed limits for ideal conditions. If conditions are less than ideal
and you do not adjust your speed accordingly, you can still get a
speeding ticket for violating California's Basic Speed Law.