Speed Enforcement
Climate Change
approaching 100 mobile speed van units and fixed
speed cameras all over our state highways, with plans
for further expansion.
An analysis was conducted comparing the results in
the first 80 days of our current program to collision sta-
tistics for the same period in 2007. When accounting for
a downward trend in fatal collisions over the last several
years, the period still showed a 30 percent reduction in
fatal collisions.
Other factors such as fuel prices and economic condi-
tions may have influenced driving behavior during the
period. However, a reduction as significant as 30 per-
cent suggests the program is effective, especially cou-
pled with Dr. Washington’s findings.
ADOT engineers’ study
Analysis by ADOT engineers further supports the valid-
ity of statistics for the first 80 days of the program. DPS
will continue to evaluate the program’s effectiveness,
and further expansion will depend on analysis of colli-
sion rates.
Where to put stationary systems is determined by
using serious injury and fatal-collision statistics for non-
peak traffic hours. Serious collisions occur primarily at
high speeds, which generally don’t occur during rush
hour congestion.
The program’s effectiveness at reducing serious colli-
sions is further improved by placing the systems in cor-
ridors approaching major junction areas. Placing the
systems closer together prevents drivers from speed-
ing up and then slowing down at each system in the
series within the corridor.
Reduced speeds, shorter stopping distances, and
more consistent speeds produced by photo enforce-
ment all contribute to safer movement of traffic in these
areas.
Few rear-end crashes
Although concerns have been expressed about
increased collisions caused by motorists braking sud-
denly when encountering the stationary systems,
Dr Washington’s study did not find a significant increase
in rear-end collisions despite the fact the pilot project
and speeding-related injuries were down 48 per cent. did not include the warning signs now in place prior to
The program was also credited with saving over all deployments on state highways.
US$16.5m per year, due to reduced property damage, With 34 stationary systems in operation in the Phoenix
medical expenses and insurance costs. area, results of the DPS programs have been consistent
Drivers exceeding the posted speed
limit were photographed by fixed and
“We documented
with Dr. Washington’s findings.
Mobile systems have the advantage
mobile cameras which were reviewed
dangerous speeders
of increasing safety over larger areas
by officials who confirm a violation has
occurred and issue a citation. At the out-
on Highway 101,
because they are not restricted to a
permanent location. They can also be
set of the highway speed enforcement
including one isued
deployed in response to changes in
pilot project, we documented danger- collision rates caused by factors such
ous speeders traveling on Highway 101,
for speed in excess
as construction zones.
including one ticket issued for a speed
of 140 mph”
in excess of 140 mph. Mobile units’ placement
Because of the conclusive results of the pilot study, we The mobile systems being used on the Phoenix freeway
have been able to implement the largest program for system will increasingly be moved to outlying areas
speed enforcement in the country. The program around the state to address serious injury and fatal col-
launched in September of 2008 and, today, we are lisions statewide. Mobile systems typically produce
www.thinkinghighways.com Thinking Highways Vol 4 No 1 31
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