Sliding down an icy road - how to stop?
Discussion
So was driving along today. Conditions: most major roads are fine (snow on edges but otherwise near-normal driving conditions) but smaller roads are still icy from layers of snow having compacted, making them worse to drive on than they were when it was actually snowing.
I'm on a fairly major road. From my rear view mirror saw a Xsara Picasso sliding down an iced up side road. The driver had done well to keep to one side, applied full lock and slid the car into the railings to stop it sliding onto the perpendicular road.
My question is as follows:
Without snow/winter tyres/socks, is there anything the driver could have done to stop the slide? He seemed to be driving as sensibly as possible for the conditions (i.e. very slowly ~2-3mph).
Hand brake up or not? I'm thinking up so back wheels are locked. Otherwise the car would be sideways?
I thought the driver had done the right thing by hitting and coming to a rest against railings on the side of the street. His wheels were angled in which stopped him sliding further. He had a decent view of the road he was joining so presumably the best route of action would be to wait until the perpendicular road was clear and then slide onto that road to regain traction.
However, is there anything else he could have done and more generally, once your car is sliding at crawling speeds, is there anything the driver can actually do to bring it to a stop or control the slide?
I'm on a fairly major road. From my rear view mirror saw a Xsara Picasso sliding down an iced up side road. The driver had done well to keep to one side, applied full lock and slid the car into the railings to stop it sliding onto the perpendicular road.
My question is as follows:
Without snow/winter tyres/socks, is there anything the driver could have done to stop the slide? He seemed to be driving as sensibly as possible for the conditions (i.e. very slowly ~2-3mph).
Hand brake up or not? I'm thinking up so back wheels are locked. Otherwise the car would be sideways?
I thought the driver had done the right thing by hitting and coming to a rest against railings on the side of the street. His wheels were angled in which stopped him sliding further. He had a decent view of the road he was joining so presumably the best route of action would be to wait until the perpendicular road was clear and then slide onto that road to regain traction.
However, is there anything else he could have done and more generally, once your car is sliding at crawling speeds, is there anything the driver can actually do to bring it to a stop or control the slide?
No, once you're into a slide on ice it's more or less all over :-(
In some conditions you might be lucky and get some grip for steering or braking but it's all on a case by case basis, there are no guarantees you'll be lucky and get that grip on ice.
There's loads of stuff you can do before hand though, with ice the aim is to avoid getting into a slide. Easier said than done with these conditions and the fact we can't just pause life till the weather clears! :-)
In some conditions you might be lucky and get some grip for steering or braking but it's all on a case by case basis, there are no guarantees you'll be lucky and get that grip on ice.
There's loads of stuff you can do before hand though, with ice the aim is to avoid getting into a slide. Easier said than done with these conditions and the fact we can't just pause life till the weather clears! :-)
IF you can see a clear escape route where you can slow down afterwards (and thats a big IF) then it might be possible to drive out of the slide, staying on the throttle for directional control rather than going for the brakes.
Other than that thin possibility, it sounds like the driver in question did the right thing by putting the car against a railing to stop it endangering others.
Other than that thin possibility, it sounds like the driver in question did the right thing by putting the car against a railing to stop it endangering others.
Had that yesterday down a steep ice covered hill with lots of parked cars and traffic coming up. Went as slowly as possible but could feel the car starting to run away and when it got to the point when braking and handbrake where not stopping the car, I managed to slew it right into a side road to come to a rest in deeper snow against a kerb.
In the example croyde mentions, particularly going downhill, very gentle use of the handbrake can help maintain rear wheel grip due to the torque reaction (effectively turning some of the car's momentum into extra downward pressure at the rear), which can help keep the car straight in the first place.
This technique can also be used on a level road surface, and is particularly effective with a front-wheel driven car. On narrow roads with a severe camber, do not commit yourself to driving it until you can see that your exit is (and hopefully will remain) clear. In a front driven vehicle, the effect is rather like being the rope in a tug-of-war: the front wheels are pulling you forwards, but the action of the handbrake on the rear wheels, is akin to being pulled backwards; the result being that, like the rope, you are 'pulled' straight from both ends.
Be very careful with this technique though; a little too much will lock the wheels (in which case release it immediately and re-apply more gently).
Find a suitable car park and practice so that you can get some feel of the effect.
This technique can also be used on a level road surface, and is particularly effective with a front-wheel driven car. On narrow roads with a severe camber, do not commit yourself to driving it until you can see that your exit is (and hopefully will remain) clear. In a front driven vehicle, the effect is rather like being the rope in a tug-of-war: the front wheels are pulling you forwards, but the action of the handbrake on the rear wheels, is akin to being pulled backwards; the result being that, like the rope, you are 'pulled' straight from both ends.
Be very careful with this technique though; a little too much will lock the wheels (in which case release it immediately and re-apply more gently).
Find a suitable car park and practice so that you can get some feel of the effect.
- DO NOT USE THIS TECHNIQUE IF YOUR CAR'S HANDBRAKE OPERATES THROUGH THE TRANSMISSION
Edited by cosicave on Monday 20th December 09:37
cosicave said:
In the example croyde mentions, particularly going downhill, very gentle use of the handbrake can help maintain rear wheel grip due to the torque reaction (effectively turning some of the car's momentum into extra downward pressure at the rear), which can help keep the car straight in the first place.
"Very gentle use" - i.e. pulling it up slightly - say half way, keeping the button pressed? Or putting it fully 'on and off'? Or a combination of both?I can appreciate that applying hand brake adds downward pressure at the rear, but then removing it will take this pressure off again. Will a cycle of adding and removing downward rear pressure help traction?
.blue said:
cosicave said:
In the example croyde mentions, particularly going downhill, very gentle use of the handbrake can help maintain rear wheel grip due to the torque reaction (effectively turning some of the car's momentum into extra downward pressure at the rear), which can help keep the car straight in the first place.
"Very gentle use" - i.e. pulling it up slightly - say half way, keeping the button pressed? Or putting it fully 'on and off'? Or a combination of both?I can appreciate that applying hand brake adds downward pressure at the rear, but then removing it will take this pressure off again. Will a cycle of adding and removing downward rear pressure help traction?
.blue:
I am talking about reaching the 'point' at which the handbrake begins to operate. Depending upon its level of adjustment as well as the type of car, the 'height' where this occurs will vary. It is vital that the wheels are allowed to rotate at all times and that at no point do you risk locking the wheels by pulling too hard. This is why I suggest a big wide open space (like a car park) for a little experimentation.
One gentle application is what I was getting at, and how long it is applied for (and the height) will vary upon conditions. Several applications, particularly if one were to do them quickly, would almost certainly result in one of them being too hard, so it is not advisable to attempt any version of cadence braking with the handbrake. - Remember the idea of cadence braking is to allow some steering control whilst still braking, therefore cadence braking is only applicable for the front wheels; and even then, only in an emergency.
Usually, the handbrake button will be held in, so as to be able to release it instantly if a change in road friction leads to a skid. The technique is most useful when travelling in a straight line and at very slow speeds which should not present a problem for steering. [However, I'll tell you that driving down a long long hill of constant gradient in the USA recently, there were times where I released my thumb to allow the button out, for several minutes at a time, in order to allow gentle steering (bear in mind that this road descends for about 14 miles).]
I repeat: practice in a car park or similar before trying this on the road and be gentle with everything you do when driving in slippery conditions.
I am talking about reaching the 'point' at which the handbrake begins to operate. Depending upon its level of adjustment as well as the type of car, the 'height' where this occurs will vary. It is vital that the wheels are allowed to rotate at all times and that at no point do you risk locking the wheels by pulling too hard. This is why I suggest a big wide open space (like a car park) for a little experimentation.
One gentle application is what I was getting at, and how long it is applied for (and the height) will vary upon conditions. Several applications, particularly if one were to do them quickly, would almost certainly result in one of them being too hard, so it is not advisable to attempt any version of cadence braking with the handbrake. - Remember the idea of cadence braking is to allow some steering control whilst still braking, therefore cadence braking is only applicable for the front wheels; and even then, only in an emergency.
Usually, the handbrake button will be held in, so as to be able to release it instantly if a change in road friction leads to a skid. The technique is most useful when travelling in a straight line and at very slow speeds which should not present a problem for steering. [However, I'll tell you that driving down a long long hill of constant gradient in the USA recently, there were times where I released my thumb to allow the button out, for several minutes at a time, in order to allow gentle steering (bear in mind that this road descends for about 14 miles).]
I repeat: practice in a car park or similar before trying this on the road and be gentle with everything you do when driving in slippery conditions.
I realised at the weekend that if you get stuck going up a hill and start to slide backwards, using the handbrake is probably a better way to adjust your speed as you are effectively then working the 'front' brakes given your direction of travel. Doing what I did, which was to pump the footbrake, just made the car spin as you lock up the 'back' brakes. It span all the way down the hill bouncing off the verges, luckily no damage other than one small plastic clip snapped on the bumper! 
Kozy said:
I realised at the weekend that if you get stuck going up a hill and start to slide backwards, using the handbrake is probably a better way to adjust your speed as you are effectively then working the 'front' brakes given your direction of travel. Doing what I did, which was to pump the footbrake, just made the car spin as you lock up the 'back' brakes. It span all the way down the hill bouncing off the verges, luckily no damage other than one small plastic clip snapped on the bumper!
What you do in that situation (with 4wd at least, may not work as well with 2wd) is grab reverse, get on the throttle to keep the wheels turning, then ease off and use the engine braking to slow down. Its somewhat counterintuitive for most people, but a well established technique off-road.If its steep enough and slippery enough it can still take a long time to stop though...
t, then try sticking it in reverse and mashing the throttle, of course this is a last ditch solution, but it stands a good chance of stopping you sliding out infront of an oncoming vehicle.GravelBen said:
Kozy said:
I realised at the weekend that if you get stuck going up a hill and start to slide backwards, using the handbrake is probably a better way to adjust your speed as you are effectively then working the 'front' brakes given your direction of travel. Doing what I did, which was to pump the footbrake, just made the car spin as you lock up the 'back' brakes. It span all the way down the hill bouncing off the verges, luckily no damage other than one small plastic clip snapped on the bumper!
What you do in that situation (with 4wd at least, may not work as well with 2wd) is grab reverse, get on the throttle to keep the wheels turning, then ease off and use the engine braking to slow down. Its somewhat counterintuitive for most people, but a well established technique off-road.If its steep enough and slippery enough it can still take a long time to stop though...
Ray Luxury-Yacht said:
GravelBen said:
Kozy said:
I realised at the weekend that if you get stuck going up a hill and start to slide backwards, using the handbrake is probably a better way to adjust your speed as you are effectively then working the 'front' brakes given your direction of travel. Doing what I did, which was to pump the footbrake, just made the car spin as you lock up the 'back' brakes. It span all the way down the hill bouncing off the verges, luckily no damage other than one small plastic clip snapped on the bumper!
What you do in that situation (with 4wd at least, may not work as well with 2wd) is grab reverse, get on the throttle to keep the wheels turning, then ease off and use the engine braking to slow down. Its somewhat counterintuitive for most people, but a well established technique off-road.If its steep enough and slippery enough it can still take a long time to stop though...
normalbloke said:
Ray Luxury-Yacht said:
GravelBen said:
Kozy said:
I realised at the weekend that if you get stuck going up a hill and start to slide backwards, using the handbrake is probably a better way to adjust your speed as you are effectively then working the 'front' brakes given your direction of travel. Doing what I did, which was to pump the footbrake, just made the car spin as you lock up the 'back' brakes. It span all the way down the hill bouncing off the verges, luckily no damage other than one small plastic clip snapped on the bumper!
What you do in that situation (with 4wd at least, may not work as well with 2wd) is grab reverse, get on the throttle to keep the wheels turning, then ease off and use the engine braking to slow down. Its somewhat counterintuitive for most people, but a well established technique off-road.If its steep enough and slippery enough it can still take a long time to stop though...
Surely grabbing reverse is as bad as mashing the brake pedal??? Wheels turning in the opposite direction must give as little grip as locked wheels, shirley?
Ray Luxury-Yacht said:
I have, and it still doesn't make as much sense as 'grabbing first gear' instead of 'grabbing reverse.'
Surely grabbing reverse is as bad as mashing the brake pedal??? Wheels turning in the opposite direction must give as little grip as locked wheels, shirley?
Maybe you misread the post I was replying to... talking about driving up a hill, losing traction and sliding backwards.Surely grabbing reverse is as bad as mashing the brake pedal??? Wheels turning in the opposite direction must give as little grip as locked wheels, shirley?
Driving forwards down a hill I agree with you completely.
GravelBen said:
Ray Luxury-Yacht said:
I have, and it still doesn't make as much sense as 'grabbing first gear' instead of 'grabbing reverse.'
Surely grabbing reverse is as bad as mashing the brake pedal??? Wheels turning in the opposite direction must give as little grip as locked wheels, shirley?
Maybe you misread the post I was replying to... talking about driving up a hill, losing traction and sliding backwards.Surely grabbing reverse is as bad as mashing the brake pedal??? Wheels turning in the opposite direction must give as little grip as locked wheels, shirley?
Driving forwards down a hill I agree with you completely.
In that case, yes of course, sliding backwards from an attempt at forwards - select reverse of course.
Ahem. As you were
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