The Arrive Alive website received a rather interesting email from a visitor warning about using cruise control when driving in wet weather. The email reads:
“I wonder how many people know about this ~
A 36 year old female recently had an accident and totaled her car. A resident of Kilgore – Texas, she was traveling between Gladewater & Kilgore. It was raining, though not excessively, when her car suddenly began to hydro-plane and the next moment, literally took off like a rocket – totally out of control – causing her to have what could easily have been a fatal accident. Fortunately she was not seriously injured but very stunned at the sudden occurrence!
When she explained to a highway patrolman who arrived at the scene what had happened, he told her something that every driver should know – NEVER DRIVE IN THE RAIN WITH YOUR CRUISE CONTROL ON. She 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 when your car begins to hydro-plane and your tires lose contact with the road, your car will automatically accelerate to a higher speed – causing you take off like an airplane when traction is regained.
She told the patrolman that was exactly what had occurred.
The patrolman said this warning should be listed – on the driver’s seat sun-visor – “NEVER USE THE CRUISE CONTROL WHEN THE ROAD IS WET OR ICY” – along with the Airbag Warning.
We tell our teenagers to set the cruise control and drive at a safe speed – but we don’t tell them to use the cruise control only when the road is dry!
The only person the accident victim could find who knew about this (besides the patrolman), was a man who had a similar accident, totaled his car and sustained severe injuries.”
Response
We referred this to our driving Expert Rob-Handfield Jones from www.driving.co.za and promptly received a response:
The cruise control story is nonsense. The biggest problem is that drivers don’t understand the laws of physics. For starters, neither the road nor the weather knows whether there is a foot on the accelerator or a servo holding it in position, so it’s an argument from ignorance. Moreover, if the cruise control could make that much difference to stability, then the driver was already way over the limit and would probably have lost control anyway.
The majority of modern cars have electronic stability control systems – if the system intervenes, it automatically retards the power, over-riding the cruise control. And even without stability control, if you aquaplane, your driving wheels (which are usually the ones whose speed is measured to set the cruise control’s speed) spin faster than your set speed and the cruise control will presume you’re speeding up and retard the power.
Also, when you aquaplane (hydroplane) you don’t just ‘take off’. All that happens is that your front wheels (usually) are no longer able to disperse the water on the road and start skimming along the surface of the water. This results in loss of steering control. So of course, if it happens at a corner and you go straight off the road over a 30-foot embankment, sure you’re going to fly, but on a dead-straight flat road, never. Most of the time, you won’t even notice you’re aquaplaning until you try to turn and the steering doesn’t work. I’ve aquaplaned hundreds of times while taking part in motorsport in wet weather, without any ill-effects except a scare or two…
The reality is that if you start aquaplaning, your speed was too high for the conditions, and that doesn’t really have anything to do with the cruise control but with the driver’s judgement. I have been using cruise control in all weathers in many different cars for decades without a problem.