each, then the impact on injury rates is the metric of importance.
wins on safety, it is too expensive (ignore service, capacity), etc.
expended in red light cameras would be better spent building roundabouts.
is a solution where all others are infeasible.
To clarify: I put "clear winner" in quotes because that was a quote taken
from the article.
With his permission, I'm sharing some thoughts from Richard Retting, who
has done significant research in both fields of roundabouts and red light
running cameras.
From an implementation standpoint, a comparison between red light cameras
and roundabouts makes no sense. This is like comparing curve warning signs
and geometric changes to realign a sharp horizontal curve; both approaches
provide established safety benefits (see HSM or CMF Clearinghouse), but
require dramatically different levels of planning, funding, and
construction.
To that I'll add a few thoughts of my own.
I think from the public's perspective, proud always to be cynical and
suspicious of government intrusions and intentions, the touted safety
benefit to the public was tainted because
- The private sector was involved with a clear profit motive.
- The revenue didn't go toward safety, but to fatten other government
coffers that had nothing to do with safety.
In hindsight, had red light cameras had no private sector involvement, no
profit motive, and the funds were dedicated solely to traffic safety
improvements, the public might have been more willing to accept them. But
the same governments claiming to be acting solely out of concern for public
safety, weren't concerned enough to themselves purchase the equipment and
provide the staff for red light cameras. The public can see it was only
when risk-free revenue was dangled before governments that this particular
interest in safety suddenly manifested itself.
Regarding the comparison to roundabouts, both attempt to alter driver
behavior and improve safety:
- Modern roundabouts accomplish this through *design*:
- T-bone and near head-on crashes are eliminated.
- The two classic pedestrian/vehicle intersection crashes are
eliminated.
- Speeds are controlled by horizontal deflection and negative
superelevation.
- Roundabout designers assign drivers the role of slowing down and
paying attention, a task well within human capability.
- By design, kinetic energy of most vehicles is effectively kept
quite low, so crash severity is also quite low.
- Events play out slowly, everything takes place in easy view, the
situation is not complex, and demands are light for static perception,
dynamic perception, depth perception, scanning (neck twisting), and time to
process perception, judgement and reaction.
- The upshot is voluntary driver safe behavior and a huge safety
payoff.
- Roundabouts are safe, gentle, forgiving friends of all users.
- They can also add to the esthetic environment and even be a key
element of a great public place. People like and respect nice places. They
relax and read and dine and socialize and take their kids there.
- Red light cameras seek to do this through the *threat of punishment*,
and *actual punishment* of offenders.
- But people don't like threats.
- Or punishment.
- Or government intrusion.
- Or bad news letters from their government.
- Or being forced to pay private companies making money off their
teeny timing errors.
- And having so much ride on split-second decisions that are part
of everyday life. After all, it's not as much the drivers who misjudged
the yellow phase by 1/2 second who cause intersection crashes as it is the
drivers who sail through a red light a little later in the red phase.
- Erring on the conservative side sometimes means braking hard at
the risk of getting rear-ended and incurring severe neck injuries. Not a
great set of options, by design.
- Signalized intersections are dangerous, harsh and fatally
unforgiving places for all users, especially vulnerable users.
- They're barren, ugly, and noisy no-man's lands, and they poison
the air. People dislike such places (and dislike being forced to spend
time there, immobilized). It's no wonder the human temptation is to try to
squeak through. You could say it's a setup to encourage slightly erring on
the optimistic side of hope to beat the red light.
- Piling on threats and punishments adds to the negativity.
- By design, signalized intersections imbue kinetic energy to
vehicles many times greater than roundabouts do, because KE = 1/2 x mass x
(velocity squared) , so crashes can be extremely severe.
- By design, signalized intersections can and do kill those who get
the signals or the timing too wrong, and anyone in the way.
- Here's how it works:
- Signalized intersection designers assign the role of *orchestrating
*tricky, constantly changing vehicle and pedestrian movements to
a system of sensors, signals and computers. This reliable equipment doesn't
actually *control *vehicle movements, it merely operates colored
lights. That's it.
- To ordinary drivers of all ages, signalized intersection
designers assign the role of *compensating *for this design by
getting the signals and the timing and the looking out for pedestrians and
fast-moving vehicles all over the place exactly right, every time, all day
long, year and year out for a lifetime, under all conditions of weather,
fatigue, distraction, and state of body and mind.
- To ordinary, non-motorized users of all ages on foot, bike,
skates, walker, cane or skates, signalized intersection designers assign a
similar compensation role.
- The penalty can be death to non-motorized users who don't
perfectly compensate for the design, every time. These highly vulnerable
users lack protection and the means to move quickly should there be a
misstep anywhere else in the complex, fast-moving and ever-changing
choreography.
- That's too much to ask of humans, as readily evidenced by the
upshot: 8,000 conventional intersection fatalities/year (including stop
control intersections)
-Ken
Ken Sides, PE, PTOE, CNU-a
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