The margin is intended to address language in the Arizona
Revised Statutes related to speed offenses that defines, "...reasonable
and prudent..." speed. It also provides a reasonable margin of error/grace
for inaccurate vehicle speedometers and short-term lapses of attention by
otherwise law-abiding and generally cautious drivers.
Our primary focus is on intentional, aggressive and
negligent drivers. Statistics tell us that at 10 mph over the posted speed
limit, the probability of being involved in a crash double. However, at
20 mph over, the probability increases to 11 times greater. We are trying
to change the driving behavior of those persons who are most likely to cause
crashes.