This from the September, 2002 Car and Driver Magazine:
Rear-end crashes go up after red-light cameras go in.
BY PATRICK BEDARD
September 2002
When the nation's No. 1 cheerleader for red-light
cameras admits there might be one teensy-weensy
downside to the program, you just know it's going to
be a lulu so large it couldn't be crammed under the
carpet without making a bulge the size of a circus
tent.
The Insurance Institute for Highway Safety (IIHS)
recently enthused over traffic-tickets-by-mail schemes
for an entire issue of its Status Report. On red-light
cameras, however, it did allow that "most studies also
reported increases in rear-end crashes."
It went on to say, "This isn't surprising. The more
people stop on red, the more rear-end collisions there
will be."
Duh!
Not to worry, however, because "photo enforcement
leads to significant overall reductions in crashes,"
assures Susan Ferguson, the institute's senior
vice-president for research.
Well, that depends on who's telling the story. The
institute itself did two studies, both in Oxnard,
California, the most recent one published in 2001.
Other studies have been done, but the IIHS roundly
pooh-poohs them. Why? Because they don't follow a
curious methodology the IIHS invented especially for
Oxnard.
IIHS insists that all red-light-camera studies must
account for "regression to the mean" and for
"spillover effects."
Regression to the mean is a fact of life; in any one
year, there could be an extraordinarily large number
of crashes at a particular intersection, but over
several years the count will revert back to average
(mean).
Funny that IIHS insists regression be accounted for in
studies at stoplights when it never considers the same
factor in its studies of speed limits.
Spillover effect is IIHS's trick for giving the
cameras credit for reducing fatalities even where they
aren't. It assumes that red-light cameras at a few
intersections will cause drivers to stop promptly all
over town, or all over the county, or maybe all over
the state, so improvements outside the cameras' ZIP
Codes are credited to them nonetheless. As statistical
acrobatics go, this one is breathtaking.
But you ain't seen nothin' yet. The obvious way to
gauge the payoff of red-light cameras is to compare
intersections with cameras to those without, then zoom
in on crashes actually caused by drivers running red
lights. Instead, IIHS considered all crashes at all
125 signalized intersections in Oxnard and concluded
that injury crashes dropped by 29 percent due to the
cameras, even though they were installed at only 11
intersections.
Spillover effect, don't you know.
Skeptics will notice that crashes went down rather
randomly all over town, and some ordinary
intersections outperformed those with the gotcha
equipment. The cameras look remarkably ineffectual
until, just in time, spillover effect arrives to
snatch victory from the jaws of ho-hum.
Skeptics will also notice that these IIHS studies,
which pretend to be about red-light running, never
bother to isolate those crashes specifically caused by
running red lights. Why? It says, "The crash data did
not contain sufficient detail to identify crashes that
were specifically red-light-running events."
This is believable only to those who've never heard of
police reports. Oxnard, like most California
jurisdictions, reports crashes according to the
California Highway Patrol protocol, which includes a
"primary collision factor," i.e., the cause of the
crash. Those reports are collected into a CHP database
(SWITRS). Running red lights falls under the category
of "stop signals and signs." According to Steve Kohler
of the CHP, it includes stop signals and stop signs.
Nothing else.
Since all signalized intersections in Oxnard are, by
definition, controlled by signals and not stop signs,
red-light running should be neatly isolated as a
"primary collision factor." When IIHS finds numbers
that support the story it wants to tell, it jumps on
them like a trampoline. When it hides from numbers as
it did in this case, you can bet they go the wrong
way.
IIHS has refused to release the study's raw data so
that others may verify its conclusions, but Jim
Kadison, a disarmingly sincere member of the National
Motorists Association, went directly to SWITRS for
crash data on the nine signalized Oxnard intersections
used in the first IIHS study. He smelled something
funny in IIHS's breakdown of crashes; just nine
percent were rear-enders. Across the nation, it's
about 40 percent, according to the National Highway
Traffic Safety Administration.
Looking at the data, Kadison could reduce rear-enders
down to a single-digit share only by narrowing the
definition of intersection to "between crosswalks."
Narrowing that way chops off the entire approach to
the intersection, exactly where rear impacts happen.
It looks like IIHS purposely designed its study to
avoid seeing rear-enders.
Sure enough, when he opened the "intersection" to
include crosswalks and 100 feet each side of them,
rear crashes rose to a more normal share. Over this
enlarged zone, rear-end crashes increased by 33 after
red-light cameras were installed. At the same time,
side impacts dropped 25 percent. Kadison concludes
that the cameras merely trade one type of crash for
another.
IIHS's claim of safety from cameras is flatly
contradicted by a number of cities that have tried
them. "At some intersections [with cameras] we saw no
change at all, and at several intersections we
actually saw an increase in traffic accidents,"
admitted San Diego police chief David Bejarano on ABC
News's Nightline.
In Charlotte, North Carolina, station WBTV had this to
say, "Three years, 125,000 tickets, and $6 million in
fines later, the number of accidents at intersections
in Charlotte has gone down less than one percent. And
the number of rear-end accidents, which are much more
common, has gone up 15 percent."
In Greensboro, the News & Record reports, "There has
not been a drop in the number of accidents caused by
red-light violations citywide since the first cameras
were installed in February 2001. There were 95 such
accidents in Greensboro in 2001, the same number as in
2000. And at the 18 intersections with cameras, the
number of wrecks caused by red-light running has
doubled."
The granddaddy of all studies, covering a 10-year
period, was done for the Australian Road Research
Board in 1995 (cameras went up in Melbourne in 1984).
Photo enforcement "did not provide any reduction in
accidents, rather there has been increases in rear end
and [cross-street] accidents," wrote author David
Andreassen in the page-one summary.
Red-light cameras turn out to be a very expensive way
to crank up rear-end crashes. Motorists in Washington,
D.C., alone pay a half-million dollars a month in
fines. That's not enough, IIHS says. It wants points
on driving records, too.
=====
Paul Misencik
1971 MGB Vintage Race Project
Huntersville, NC USA
www.sopwithracing.com
Learn the truth at www.misleader.org
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