Cruise control + wet roads....yes its that email!!
Discussion
Hey guys,
I would be interested to see your comments on the story that is written below. I have seen this email a few times and I hate because personally I think it is full of incredibly bad advice.
I believe the only reason someone could lose control with the cruise control set is because they have set it to an innapropriate speed for the conditions and when the car does aquaplane the driver tries switch off the crusie control and slow down by hitting the brakes resulting in a loss of control (as I understand it).
Hmmm it does say though that with cruise control set my car will become airborne...can I stop buying tyres now and fly everywhere
The story:
I wonder how many people know about this ?
A 36-year-old had an accident several weeks ago and totalled her car. A resident of Wollongong , NSW, she was travelling between Wollongong & Sydney . It was raining, though not excessively, 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 policeman 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 policeman told her that if the cruise control is on and your car begins to hydroplane -- when your tyres lose contact with the pavement, your car will accelerate to a higher rate of speed and you take off like an airplane. She told the policeman that was exactly what had occurred.
The policeman estimated her car was actually travelling through the air at 10 to 15 kms per hour faster than the speed set on the cruise control.
The policeman said this warning should be listed, on the driver's 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 road is dry.
The only person the accident victim found, who knew this (besides the policeman), was a man who had had a similar accident, totalled 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.
I would be interested to see your comments on the story that is written below. I have seen this email a few times and I hate because personally I think it is full of incredibly bad advice.
I believe the only reason someone could lose control with the cruise control set is because they have set it to an innapropriate speed for the conditions and when the car does aquaplane the driver tries switch off the crusie control and slow down by hitting the brakes resulting in a loss of control (as I understand it).
Hmmm it does say though that with cruise control set my car will become airborne...can I stop buying tyres now and fly everywhere
The story:
I wonder how many people know about this ?
A 36-year-old had an accident several weeks ago and totalled her car. A resident of Wollongong , NSW, she was travelling between Wollongong & Sydney . It was raining, though not excessively, 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 policeman 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 policeman told her that if the cruise control is on and your car begins to hydroplane -- when your tyres lose contact with the pavement, your car will accelerate to a higher rate of speed and you take off like an airplane. She told the policeman that was exactly what had occurred.
The policeman estimated her car was actually travelling through the air at 10 to 15 kms per hour faster than the speed set on the cruise control.
The policeman said this warning should be listed, on the driver's 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 road is dry.
The only person the accident victim found, who knew this (besides the policeman), was a man who had had a similar accident, totalled 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.
Well, let's assume a car with no traction control and a gearbox-driven speed signal.
Driver is on a slippery road. The driven wheels lose traction, but all the cruise control knows about is maintaining the power for the wheels to turn at an angular velocity sufficient for the set speed.
Imagine now the situation of a rear wheel drive car on ice, travelling at 5mph but with the rear wheels rotating at equivalent of 35mph. Plus numpty driver behind wheel.
If the speed signal is taken from somewhere not related to the drive wheels, then it could get very nasty indeed as the system goes into a loop - "Car travelling slower than set speed, increase throttle."
I'm guessing it's not so much of a problem with traction control, depending on how witless the system is or isn't.
Driver is on a slippery road. The driven wheels lose traction, but all the cruise control knows about is maintaining the power for the wheels to turn at an angular velocity sufficient for the set speed.
Imagine now the situation of a rear wheel drive car on ice, travelling at 5mph but with the rear wheels rotating at equivalent of 35mph. Plus numpty driver behind wheel.
If the speed signal is taken from somewhere not related to the drive wheels, then it could get very nasty indeed as the system goes into a loop - "Car travelling slower than set speed, increase throttle."
I'm guessing it's not so much of a problem with traction control, depending on how witless the system is or isn't.
Don said:
Where is the speedometer sensor in most cars these days?
In most modern cars I'd expect a feed off the ABS computer, at least that's been the case with my last two cars. As to which signal it uses (whether it's just one of the wheel speeds, or a calculated speed) I expect that would vary quite a bit.
Gearbox certainly used to be fairly common before the advent of computers everywhere.
I remember reading about cars sold in the USA a few years ago with traction control sensed off the non-driven wheels, that had the nasty habit of going to full throttle if the driven wheels aquaplaned. I don't suppose that this design mistake is likely to be repeated though and I'm sure it isn't widespread.
Cruise control is not good in standing water, I fully agree. But suggesting a car could "take off" is pony! 
I did have a minor "incident" in my old E39 BMW 5-series touring with the traction control engaged, hitting standing water. Luckily I got the clutch in without major problems but the last thing you want is continued acceleration in that situation and that is exactly what the cruise wants to do!!
I did have a minor "incident" in my old E39 BMW 5-series touring with the traction control engaged, hitting standing water. Luckily I got the clutch in without major problems but the last thing you want is continued acceleration in that situation and that is exactly what the cruise wants to do!!
pdV6 said:
I'm probably wrong, but the way I see it is if the car looses traction and the wheels therefore accelerate relative to roadspeed, surely the cruise control would throttle back to compensate - which would have the exact opposite effect to that described in the email?
Exactly my thought.
I guess if you hit deep water and the car was slowed down by it then the cruise would ramp up the throttle but the fact that the car was slowed down suggest the car has driven in to the water and not over it...even then though if its anything like the cruise control on my car it only increases speed in 2KMH increments and even if you hold the button down it keeps increasing seed in 2KM increments every couple of seconds. If the ECU is doing the accelerating for me then it is such a gentle throttle input that even on ice I reckon it wouldnt spin the wheels
deviant said:
if its anything like the cruise control on my car it only increases speed in 2KMH increments and even if you hold the button down it keeps increasing seed in 2KM increments every couple of seconds. If the ECU is doing the accelerating for me then it is such a gentle throttle input that even on ice I reckon it wouldnt spin the wheels
I think mine depends on how far away you are from the target speed. Set cruise at 70, back off to 40, hit resume and it floors it!
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