Can Using Cruise Control In Wet Weather Cause An
Accident?
This message first came out in November of 2002.
no researcher has been able to
confirm the story itself, although there's is some reason to doubt it. As usual, some of the text has
been changed over time.
First, let me
address why the supposed explanation by the supposed Highway Patrolman
does not make sense. This is an excellent illustration sent to me
by reader Gary Panulla.
Let's start with the basics:
Cruise control adjust the throttle only (gas pedal). It is in no
way, shape or form connected to the breaking system of a vehicle.
It measures your speed using "a speedometer like" sensor and adjusts the
throttle. to maintain the set desired speed.
Let's say your traveling
down the road with cruise control on. You start to go down hill. What
happens? At first, gravity begins to speed up the car a little above
where you had the cruise control set. The cruise control begins to
"throttle back" (you can hear the engine "slow" a little). The longer
you go down hill, the more the cruise control "throttles back" to keep
the speedometer reading where you set the cruise control. When you reach
the bottom of the hill and begin to climb another. Now what happens?
Well the car now begins to slow as gravity acts in the opposite
direction and the speedometer shows just that. The cruise control
increases the throttle slowly and your speedometer reading (and your
forward speed) are maintained. Simple enough, right?
So, as you can see, when the
wheels (and the speedometer reading) slow down (going up hill), the
cruise control increases the throttle. When the wheels (and the
speedometer reading) speed up (going down hill) the cruise control
decreases the throttle.
Now think about the last
time you tried to start at a light when the road was slippery. If you
apply too much gas (throttle), the wheels break free. You can "feel"
this in your foot. The speedometer swings widely and show a speed of 50
or more MPH. You know you are more or less "just sitting still", but the
speedometer "thinks" you are doing 50! (Actually the wheels are spinning
as fast as if you were going 50! but you know better, the car does not!)
Now let's combine the two.
Your traveling down the road with the cruise control on. You hit a patch
of ice and the tires break free. The speedometer swings widely upwards.
The cruise control "thinks" you've started down a very, very steep hill
and immediately "throttles back" to try and slow you down! (and if you
kept your foot near the accelerator, it would "slap back" against your
foot!)
Now remember the quote: "He
said if you did and hydroplaned (which I did) that when your tires were
off the road your car would accelerate to a high rate of speed (which it
did). You don't have much, if any control when you hydroplane, but you
are totally in the hands of God when the car accelerates. I took off
like I was in an airplane."
The "(which it did)" is a
total fabrication, the cruise control computer would have responded with
the CORRECT action of releasing the gas pedal faster than even the most
seasoned winter driver!!!
So, either the policeman was
telling a "fib" and the "driver remembered" that facts in a way to
support it, OR. . . . It's a total "urban legend", complete with victim
(driver who never knew better), authority figure (the knowing policeman)
to lend credence to the story, and a "this could happen to you" content
to "get you attention."
Still, the general consensus is that cruise control should not be
used in any wet conditions. This is not because of any unsafe issues
with the cruise control itself, but mostly because of two issues:
disengaging the cruise control by braking and "road feel." Braking in a skid is problematic. Our
first tendency is to brake when steering and gradual slow down are the
keys to control. There is also an issue about not being able to "feel"
the road and gauge what is happening with cruise control on. I've gotten
quite a bit of good info about this from some knowledgeable people.
According to a defensive driving school instructor, The problem with
driving in any inclement weather with cruise control on is that you
cannot tell what the car is doing when your foot is not in contact with
the gas pedal. He calls it reading the vehicle language. So, you really
cannot tell if you are hydroplaning or not. The upshot is
that cruise control is great, but only optimal weather conditions.
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Original Message:
I had a
wreck a couple of weeks ago and totaled our Lincoln Town Car. I
hydroplaned on Hwy 135 between Gladewater & Kilgore, Texas. I was not
hurt, just emotionally rattled! I know the Lord was with me.
I learned a lesson I'd like to pass on to you. You may know this already
— but the highway patrolman told me that you should NEVER drive in the
rain with your cruise control on. He said if you did and hydroplaned
(which I did) that when your tires were off the road your car would
accelerate to a high rate of speed (which it did). You don't have much,
if any control when you hydroplane, but you are totally in the hands of
God when the car accelerates. I took off like I was in an airplane. I'm
so thankful I made it through that ordeal. Please pass the word around
about not using cruise control when the pavement is wet or icy. The
highway patrolman said this should be on the sun-visor with the warning
about air-bags.
The only person I've found out who knew this (besides the patrolman) was
a man who had a similar accident and totaled his car. This has made me
wonder if this is not why so many of our young people are dying in
accidents.
Be careful
out there!
VERSION # 2:
Some good advice, and you
may know this already, but it is good to repeat!
A 36 year old female had an accident several weeks ago and totaled her
car. A resident of Kilgore, Texas, she was traveling between Gladewater
& Kilgore. It was raining, though not excessive, when her car suddenly
began to hydroplane and literally flew through the air.
She was not seriously injured but very stunned at the sudden occurrence!
When she explained to the highway patrolman what had happened he told
her something that every driver should know NEVER DRIVE IN THE RAIN WITH
YOUR CRUISE CONTROL ON. She had thought she was being cautious by
setting the cruise control and maintaining a safe consistent speed in
the rain. But the highway patrolman told her that if the cruise control
is on and your car begins to hydroplaned - when your tires loose contact
with the pavement your car will accelerate to a higher rate of speed and
you take off like an airplane.. She told the patrolman that was exactly
what had occurred.
We all know you have little or no control over a car when it begins to
hydroplane. You are at the mercy of the Good Lord. The highway patrol
estimated her car was actually traveling through the air at 10 to 15
miles per hour faster than the speed set on the cruise control.
The patrolman said this warning should be listed, on the drivers seat
sun-visor - NEVER USE THE CRUISE CONTROL WHEN THE PAVEMENT IS WET OR ICY
along with the airbag warning.
We tell our teenagers to set the cruise control and drive a safe speed
but we don't tell them to use the cruise control only when the pavement
is dry. The only person the accident victim found, who knew this
(besides the patrolman), was a man who had had a similar accident,
totaled his car and sustained severe injuries.
If you send this to 15 people and only one of them doesn't know about
this, then it was all worth it. You might have saved a life. |
