PHOTO RADAR SYSTEMS
The term “photo radar” is frequently only
half right. Yes, the system always snaps a photo of a
vehicle it considers to be speeding, but it doesn’t
always measure that speed with radar.
Back in the eighties when it began appearing in a few
U.S. municipalities, “photo radar” was the
name applied to a mobile system using European equipment
such as the Swiss-made Multanova. These devices were,
and still are, packaged in vans. The enforcer drives to
a location, at which point he makes a quick set-up that
includes positioning a radar gun on a tripod along the
road and aiming his cameras. The radar beam, almost always
Ka band, is angled across the road, thereby weakening
the signal available to approaching radar detectors.
After an hour or two in one location, these photo-radar
units usually move on to a new ambush.
Camera enforcement of traffic speed doesn’t always
use radar, however. In fact, non-radar systems are on
a fast growth track now. There are four types you should
1. Speed On Green. Red light cameras are used in
more than 100 U.S. communities, according to the Insurance
Institute for Highway Safety. Many of these systems use
wires buried in the pavement to sense when cars enter
the intersection. With a software change, many of these
systems can be updated to do a time-distance calculation
between the buried sensors, thereby indicating vehicle
speed. If a violation is detected, the cameras already
in place for red-light monitoring will picture the accused
speeder. And the ticket will be issued by the same system
in place for red-light violations. Adding this speed-on-green
feature brings automated speed enforcement on the cheap.
warning on this threat: None; it’s neither radar
Permanent Speed Cameras. Early in 2006, camera
enforcement began along the 101 freeway in Scottsdale,
AZ, with three cameras monitoring each direction over
a 7.8-mile stretch. This is the first photo-speed enforcement
on a U.S. freeway. The equipment is owned and operated
by Redflex Traffic Systems, Inc., a wholly owned subsidiary
of an Australian company, Redflex Holdings Ltd.
cameras are triggered by piezo loops buried in the pavement,
a separate loop for each of three lanes. This allows the
system to know which vehicle to accuse. Photos are taken
by two cameras mounted on posts along the right side of
the road, one shooting a front view to capture the driver’s
face, the other aimed at the rear license plate.
V1 warning on this threat:
None; it’s neither radar nor laser.
3. Photo Laser. Redflex says it has one fixed-in-place
camera-enforcement system using laser to measure speed,
now operating in a mid-western U.S. city. It also offers
a version of the van-based mobile system that substitutes
laser for the radar. We can’t predict the growth
rate of these laser systems. For sure, they will present
a challenge to the idea of early warning from a laser
detector, but they certainly will not be immune to detection.
warning on this threat: Maybe, depends upon situation.
Point-to-point speed systems. These systems are
intended for limited-access highways where they would
measure time intervals for each vehicle between points
several miles apart or even farther. Imagine an automated
VASCAR on a giant scale. Such a system would have beginning
and end points, each consisting of an overhead structure
with vehicle-recognition sensors covering each lane. One
sensor array records each vehicle entering the monitored
stretch, another watches the exit. If a vehicle traverses
the distance faster than allowed, its picture is taken
by cameras along the road.
No systems of this sort are operating in the U.S.
warning on this threat: No; this is a vehicle-recognition
system not capable of measuring instantaneous speeds.
speed enforcement is sure to grow. Cities have found the
promise of revenues to be irresistible. Redflex is now
the largest of the contractors supplying photo-enforcement
services within the U.S. Its primary business has been
red-light cameras, but it’s telling investors that
community support is emerging for speed cameras and it
expects the U.S. market will grow to $4-10 billion dollars,
even larger than the red-light business which, it says,
has the potential to reach $1-3 billion.