Hills, snow and ice

darich

tomstickland wrote: »

I'll be reducing my stopping distance by applying the brakes.
I'm talking about driving down icy hills here btw.

It's already been discussed here that ABS on ice is pretty much ineffective. So by selecting neutral you're disengaging the best thing for keeping your speed down. It's also illegal and the highway code advises against it http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_070304

tomstickland wrote: »

If I use the engine to slow me down then it will be doing it via the front wheels alone.

Regardless - it's illegal, you have less control of the car(despite any argument you may make) and on an icy downhill road with ineffective ABS yo're effectively rolling with no brakes.

tomstickland wrote: »

Since when has the engine and gearbox been classified as a safety device?

If it helps you maintain control of the vehicle in a safe manner then it's a safety device for that purpose.

tomstickland wrote: »

You want to avoid someone using a technique to provide better control on icy hills. Best of luck to you.

As Alastairq stated - you're creating a one tonne (probably more depending on your car) toboggan with ineffective braking system. By selecting neutral which is against the highway code and claiming it gives you better control (when it doesn't) tells me that you're best avoided on the road. This is backed up by the comment you made on the video of the idiot driving on the hard shoulder and you reckoned his spin was caused by changing lane too quickly!?!?!?

Oh dear.

Rossy.

anewman wrote: »

Does anyone have any experience of driving with technology like ESP in the snow/ice? Does it really help? I understand the way it works is to monitor wheel speed and if one deviates to apply the brakes to the others or something. It sounds great, but in practice but I can't imagine it would be totally infallible, especially if going out of control at great speed.

I had it in my Renaultsport clio 197.

Was ok last year in the snow abeit a bit sensitive resulting in loss of power at crucial moments

In normal day to day driving i always switched it off. Going round a roundabout swiftly would always cut the power when trying to power out of the roundabout.

ESP whilst the jist of it is pretty cool, the practicality of it is useless

skiddlydiddly

To simplify it for those not used to engine braking, your driven wheels will resist turning as it takes a lot of power just to turn an engine and drivetrain, if you let it just tick over then it acts as a brake going down a hill, without the risk of them locking up(unless you do something stupid like drop it in 1st at 30mph).It might(in most cases) only be 2 wheels slowing you down but its the way they do it that shines in these weather conditions.
Plus you have the brakes on top of this if necessary.

tomstickland

darich wrote: »

It's already been discussed here that ABS on ice is pretty much ineffective. So by selecting neutral you're disengaging the best thing for keeping your speed down.

I haven't got ABS.

Regardless - it's illegal, you have less control of the car(despite any argument you may make) and on an icy downhill road with ineffective ABS yo're effectively rolling with no brakes.

If you're driving down a steep, icy hill you will have more control in neutral and modulating the brakes, releasing them as soon as the car starts sliding. It's basic skid control technique taught on skid pans.

By selecting neutral which is against the highway code and claiming it gives you better control (when it doesn't) tells me that you're best avoided on the road.

It does give better control on steep, icy hills. There are two reasons for this.
1) All four wheels are being used to slow the vehicle rather than 2.
2)If the car starts to slide then releasing the brakes allows the wheels that would normally be driven to obtain maximum grip because they are free to rotate at the same speed as the ground is passing below them.

This is backed up by the comment you made on the video of the idiot driving on the hard shoulder and you reckoned his spin was caused by changing lane too quickly!?!?!?

Oh dear.

Yes, the 4x4 owner lost control in part by changing lane too quickly. I'm sure you can go and find me a quote somewhere that explains that a sudden change of speed or direction is not good practice on slippery roads.

I think you've missed my earlier point that this applies to steep hills. On flatter ground then selection of the correct gear will prevent the vehicle from picking up speed in which case there is no need to use the brakes.

In the situations I'm talking about the car will be sliding as soon as too much braking is applied. Steep, icy hills. Going down slowly in neutral and using the brakes to control the speed provides better control than descending in 1st or 2nd gear.

I use engine braking a lot in dry situations by the way.

tomstickland

skiddlydiddly wrote: »

To simplify it for those not used to engine braking, your driven wheels will resist turning as it takes a lot of power just to turn an engine and drivetrain, if you let it just tick over then it acts as a brake going down a hill, without the risk of them locking up(unless you do something stupid like drop it in 1st at 30mph).It might(in most cases) only be 2 wheels slowing you down but its the way they do it that shines in these weather conditions.
Plus you have the brakes on top of this if necessary.

However, if you go down a steep hill using engine braking there is a risk that the front wheels will break traction because they are doing all of the braking. If this happens then put your foot onto the clutch as soon as possible.

tomstickland

http://www.sgi.sk.ca/sgi_pub/road_safety/drive_right/poor04.html

Skids usually take place on slippery surfaces like water, snow and ice when drivers brake or accelerate too fast or turn too sharply.

ven the most skilled drivers can find themselves in a skid. If it happens to you, it's important to know what to do.

• Remain calm. Apply steady pressure to the brakes, shifting to neutral and searching for traction. Your tires will often find better traction if you move out of the slippery tracks in your lane.

Paradigm

tomstickland wrote: »

However, if you go down a steep hill using engine braking there is a risk that the front wheels will break traction because they are doing all of the braking. If this happens then put your foot onto the clutch as soon as possible.

I'm kinda leaning towards ^^^^ this.

I have a front wheel drive car & while I use engine braking on hills to some extent, I always depress the clutch if I have to use the brakes.

My (possibly) warped thinking being that as all the engine braking is acting on the front wheels, I don't want to add extra braking forces to the same two wheels (given that all braking systems apply more force to the front than the rear) & risk a total loss of grip.

tomstickland

I think there was some confusion that I was advocating coasting along on slight hills or flat roads; I wasn't. My advice related specifically to steep hills.

I think there is also some misunderstanding in terms of what "using the brakes" meant. I meant applying gentle pressure so that all four wheels are generating a retarding force acting on the vehicle. Not hammering them in an attempt to stop dead.

In icy conditions then control of a vehicle can be maintained by putting the vehicle into neutral so that the driven wheels are free to find the correct speed to rotate at. This is the basis of skid control in icy conditions.

Add all of that up and it means that neutral or clutch down plus carefull application of the brakes will provide better control than using engine braking.

I had a hill last year where I descended the whole thing at walking speed in neutral and gently applying the brakes to control my speed. Even then the car would start sliding occasionally, in which case I would release the brakes before reapplying them.

darich

tomstickland wrote: »

I think there was some confusion that I was advocating coasting along on slight hills or flat roads; I wasn't. My advice related specifically to steep hills.

The confusion stemmed from you stating you'd rather be "coasting in neutral" without qualifying that with "when travelling down a steep hill"

tomstickland wrote: »

I think there is also some misunderstanding in terms of what "using the brakes" meant. I meant applying gentle pressure so that all four wheels are generating a retarding force acting on the vehicle. Not hammering them in an attempt to stop dead.

I don't think anyone advocates jumping on the brakes - it's the worst thing you can do in slippery conditions.

tomstickland wrote: »

In icy conditions then control of a vehicle can be maintained by putting the vehicle into neutral so that the driven wheels are free to find the correct speed to rotate at. This is the basis of skid control in icy conditions.

Add all of that up and it means that neutral or clutch down plus carefull application of the brakes will provide better control than using engine braking.

I think you're taking it slightly out of context. The article you linked to from the Canadian website said if you find yourself in a skid, one way to come out of it was to select neutral as you quoted. However you seemed to stating that method was what you used to prevent sliding.

tomstickland wrote: »

I had a hill last year where I descended the whole thing at walking speed in neutral and gently applying the brakes to control my speed. Even then the car would start sliding occasionally, in which case I would release the brakes before reapplying them.

I've been in situations before where I don't want my speed building to any more than walking pace, just like you last year. By leaving the car in gear and using a combination of brakes and clutch control it's quite easy to keep the speed down. If I hadn't used the clutch then the speed can be so low the car either stalls, or the engine turning wants the car to accelerate - neither of which are desirable (or safe).
I still don't agree that selecting coasting in neutral is the best or safest method for preventing a slide.

bigjl

I find the Ice Road Truckers program quite informative about driving on ice and snow, they always talk about not using the brakes when going downhill and always using the gears to control speed, in fact they talk about never using the brakes on a descent as it will just cause the truck to jack-knife.

From what I already knew and what I have seen on that program then the most dangerous thing to do on snow or ice would be to freewheel and rely on the brakes to control speed, the brakes don't control the speed but rather reduce it, with the car in the correct gear the speed is controlled and therefore doesn't need reduced.

Much in the same way that you would decend a hill when offroading, you would do it with the engine controlling the speed, and not brake, obviously some 4x4s have hill descent control which I think may work using the brakes but I don't know for sure, but I have never heard or seen anybody putting a 4x4 in neutral and controlling the descent with the footbrake.

When it comes to driving down hills in the ice and snow I think I will listen to the knowledge and experience of people from Alaska and the really cold parts of Canada.

I still remember when there was concern about ABS in ice and snow, mainly from Scandanavian countries, which resulted in the button on early ABS equipped Audis that allowed you to turn it off.

I am sure that ABS systems these days don't function below 5 mph for the same reason, as if you slam on the brakes in icy conditions then the ABS would make the stopping distance larger at really slow speeds, much in the same way as a skier or skater comes to a sudden stop, locking the wheels at very slow speeds results in a shorter stopping distance. Simply because there is not enough grip and the ABS can't sort it out.

Now I can't remember where I read some of that, mainly due to the fact that to do so would push some more important info out of my brain, like where the off licence is. But you are more than welcome to take my word for it, if you think about it logically it does make sense.

Though Tom is correct in that with very deft brake usage you can control your descent speed, but if the car hit a small bump then your foot would be bumped aswell and this would result in the wheels locking and loss of control, once control is lost in such conditions then it is almost impossible to regain it due to the lack of grip.

This fact alone would make using the engine to provide speed control both safer and more progressive.

It would be nigh on impossible to control a car on a 2 or 3 mile descent using the brakes for example, whereas just leaving the car in gear means you can concentrate on forward vision and planning your descent.