Driving on snowy roads, advice requested

In My Humble Opinion
1

Whats the best plan of action when you are driving on a road in winter, the pavement is wet but not really that snowy, but over a ridge you see the road is covered by snow due to wind. I have always though the best method to deal with this is slow down before the snow patch then drive through with a slight pressre on the gas. I don’t know if this is the best way, but it has worked so far.

Does anyone know what one should do? Does it make a difference with FWD vs RWD vs 4WD (locking system) vs AWD? Does ABS make a difference?

Also another question, if driving and one set of wheels enter deep snow while the other is in shallow sanded salted slushy snow, what would happen if one slammed on the brakes w/ ABS?

2

Slow down before the snow patch to a speed that you can take any curves at safely, while trying to leave yourself enough momentum to coast through the patch if you can’t accelerate safely.

Think of it from a resource allocation standpoint. Your tires only have so much friction between themselves and the road. Stopping (or slowing down) takes a lot of friction, speeding up takes a lot of friction, and turning takes a lot of friction, so if the road is truely slippery, you can’t both turn and change your speed at the same time without losing control.

If you have a RWD car, you can increase your friction artificially by putting weight in the back of the vehicle. On a FWD car, the weight of the engine is already increasing your friction. 4WD/AWD makes no difference if all 4 wheels are on the same surface, a point missed by a lot of idiots who end up in the ditch (luckily, 4WD/AWD make it easier to get out of the ditch).

ABS only makes a difference when you’re stopping, obviously. If you slam on the brakes on a slippery road without ABS, your wheels will lock up and you’ll probably end up rotating in a circular fashion. With ABS, the system wil automatically release the brakes at the point of slippage and then reapply them, performing automatically the function of “pumping your brakes”.

If the ABS is working perfectly, you’ll stop normally in your situation (well, not normally, it’ll still take a bit longer than usual to stop, but you should stop without incident).

Something you didn’t mention, if you have a stick shift you should downshift to one gear lower than you’d normally drive at. This just gives you more control of your speed.

-lv

3

ABS only affects your ability to steer while stopping…a full-lock brake will stop just as quickly as an ABS one with all other factors (including the make of car) being the same. The importance of ABS is that it enables you to steer, when otherwise you’d be sliding in a straight line. Irrelevant to sheets of ice, more important when there’s a pedestrian in front of you.

4

Temperature, water content and condition of the road makes a big difference. Temperatures right at freezing make for slicker conditions than very cold temps.

Buy good tires. Experiment with the conditions if you have the chance.

I drive in snow nearly 50% of the time. If I’m not sure of conditions, I’ll test them, so I don’t get surprised. On a clear stretch of road, with no other cars around, brake hard. See what it takes to break loose. I’m lucky in that I have many places I can do this and not worry about other traffic.

5

Avoid having to use your brakes at all. Leave enough distance between your car and the one in front of you so that you can coast to slow speed before braking. When you do brake, do so lightly.

Improper use of brakes is the biggest cause of winter driving accidents.

6

I think the number one thing is to really Slow Down. On numerous occasions I’ve driven in Portland and Seattle when it snows (which if my feeble memory is any guide happens about once every 5 years or so). The biggest problem is that morons try to drive at the same speed that they would use on dry roads (and often these are the same idiots who drive to fast on dry roads anyway). And they try to pass people, or speed up to make a light, etc.

You just want to leave yourself a considerable margin of error. And, if you have ABS remember don’t pump your breaks.

Whether driving straight over a slick patch or going around a curve (but especially the latter) you want to be giving the car a little gas rather than coasting. At least that’s what I’ve always heard, and it has always worked for me. It seems to improve the contact between the tires and the road.

7

Well in a word no.
Locking the wheels will increase the stopping distance. For the shortest stop the brakes need to held on the verge of locking up.

While shorter stopping distances is not one of the design critera of ABS, it may result in this, or in a longer stopping distance.

On dry or wet pavement a good* ABS system will almost always out stop the same car without ABS. This is due to the fact that the ABS system can pump individual brakes (something you can’t do) at a rate of up to 10 times per second. (a rate you can’t approach) bottom line is a good ABS system will out stop the same car sans ABS about 999 out of 1000 under these conditions.

Now on to snow. Without ABS slam on the brakes (assuming you are going straight) and the car will continue in a straight line and come to a stop with a pile of snow in front of each wheel. During the stop you will have no steering contol.
Add ABS and the wheels will not lock and steering will be maintained, but and this is a big but you will take longer to stop as those little piles of snow won’t build in front of your tires. So you trade off a longer stopping distance for control.

My suggestions for driving in the snow are [ul]
[li]good tires, all season as a minium, snow tires are better[/li][li]be smooth, drive like there is an egg under your foot at all times. the less abrupt you are in control inputs the less likely you are to lose control[/li][li]Too much power is a bad thing. very light throttle applications[/li][li]know what to do when the car skids (Hint turn the wheel the way you want the front of the car to go)[/li][/ul]

*****The above comments are concerning a good ABS system. There are some cars out there with craptacularly bad ABS systems. YM(or ABS system)MV

8

Be cafeful with stickshifts as well. you have to realize that when you gear down and let off the clutch you are also doing another type of breaking as well. If you start sliding towards a barrier, press in the clutch to get the wheels moving freely again, so you can get some steering traction and less stoping traction. Sure you won’t stop, but it’ll keep you from hitting a tree. Once you get back on the right track then gently apply the brakes some.

9

Acceleration while going around a curve can actually be a big no-no. It’s worse in a RWD than FWD car, but it’s just not a good idea. LordVor explained this well: resource allocation. It takes a certain amount of force (acceleration) to make your tires break traction with the road. When you turn, you are accelerating even if you have your foot off the gas. This puts force on the tires. Giving the car puts MORE force on the tires. The more force you have on the tires, the more likely they are to lose grip. In slippery weather, don’t apply gas until you’ve straightened out of the turn.

General advice is to slow down and leave plenty of room between yourself and other vehicles on the road. This is probably the most important thing you can do. This is true even if you have AWD. AWD helps you maintain grip while moving. It does NOT make you slow down any faster.

Also, if you are driving in snow and in winter, at some point you are going to slide. The basic, catch-all advice for this situation is to steer into the skid. There are some little specifics that differ between FWD and RWD drive cars, however. In a RWD car, it is the rear wheels that will slide. What this means is that when you skid, you rear end of your car is going to swing out to either the left or right. Get off the gas and steer into the skid. Chances are good that you’ll then have to steer back the other direction as the back end skids to that side. Just keep steering into the skid.

FWD cars are a little different because you can do a couple of different things depending upon your speed. At low speeds (as in, going up a driveway speeds, not 30mph) the front end may slide to the left or right as you apply power and the wheels spin. Dealing with this is simple: just turn the wheel in the direction you want to go. This could mean you turning the steering wheel like crazy and looking like a fool as the front of your car slides left and right, but hey, you made it up your driveway, right?

At any kind of real speed on a real road, this is NOT a good idea. The way a RWD drive car skids is that (around, say, a turn) the front tires keep traction while the rear wheels slide, and so the rear end of the car slides toward the outside of the car. In a FWD car, the front wheels will lose traction and slide. What this means is that the front wheels are turned, but the car is continuing to move in a straight line. This, you might understand, is a Bad Thing. At this stage, you have a couple of options:

1: Just brake. If you’re going slow enough, this might be the best idea, and unlike in a RWD skid, you still have some braking power available at the rear wheels. But you have to be going slow for this to work.

2: Steer into the skid. It’s simple, but a little different from steering into a RWD skid. Instead of turning the wheels completely in the opposite direction, you just want to get them facing in the direction you are moving, which is usually straight forward. Once you get them straight, you again have a couple of options:

a: Brake. You can brake much more effectively with four wheels than with two!

b: Attempt to steer back onto the course you want to follow. This could result in you sliding all over again.

Use your judgement, obviously. And to be fair, it’s going to be hard to go through all of this. The most that most of us would be able to do would be to think “Sliding!? BRAKE!” - which in a FWD drive car, isn’t the worst thing you could do, but which is useless in a RWD car. So practice. But the best thing to do is to go slow, which minimizes the consequences of an unexpected skid, i.e. you slide onto the shoulder and come to a quick stop, versus you careen off the road, through the guard rail and down the ravine into the river.

Also, one more thing about AWD and 4WD: while these systems are great for maintaining traction and staying on the road (AWD more than 4WD) they aren’t immune from skidding. In fact, it can be especially dangerous to slide in an AWD car because, unlike a FWD or RWD car, you cannot predict in which manner the car is likely to skid - it can go either way, or neither (and a slide in which all four wheels are out of traction with the road is not something I would wish on my worst enemy). So drive slow, keep your distance, and be careful!

Sorry for the long post y’all.

10

I’ve always found the phrase “steer into the skid” vague. It reminds me of “sail into the wind”, meaning go against the flow–i.e. if you’re skidding clockwise you should turn left (the direction you want to be going)–but that seems too natural to have its own phrase. And the last time I tried getting out of a skid in an RWD vehicle by turning in the direction I wanted to go, I ended up hanging from my seatbelt in a freeway median, after spinning my van 180 degrees and rolling it onto its side.

So, just to clarify… steering into the skid means turning the wheel to match the direction the car is already turning, correct? If you’re skidding clockwise (rear wheels sliding to the left, or front wheels sliding to the right), you want to turn to the right?

11

One other one: maintain a steady speed when approaching a snow covered hill. Don’t punch the gas but just maintain a steady cruising speed up the hill. If you slow at the bottom and attempt to accelerate on the way up your wheels will probably start losing traction.

Rick’s advice on ABS is dead on, IMO. (Just interjecting a little what he said to save typing, doncha know. Why try to improve on excellence?)

Overall, just avoid sudden movements; braking, acceleration or steering. But no matter what kind of vehicle or tires, slow down. It makes me crazy trying to avoid idiots whipping along like they’re on dry pavement. Steady and gentle will get you there faster and safely.

12

That’s not correct. It may not make as much difference as idiots who end up in ditches thought it would, but having all four wheels powered gives essentially twice as much traction as having only two powered. It only makes no difference at all when there is no traction at all.

My experience with AWD vehicles is that they are more “sure-footed” than 2WD vehicles on any type of road surface – dry, wet, sandy, icy, etc. Of course, twice as much traction on ice is often still very little traction.

13

Rick, as always, good car advice. Also the comments by TVeblen and keeping up the momentum!

A 4WD system will lock all four tires which can help a lot with braking.

I think it was in Car and Driver where I read to drive like you have a vile of nitro on the dash. If one drives so that the vile is not disturbed, you will not over do the friction thing that LordVor
was talking about.

Try to hit the slick part straight and stay straight. If the tires on one side, usually the right side in the US, get into deeper snow, the car will want to pull/turn to that side. A firm grip of the wheel and be ready. I also test the road so that I know what I’m driving on.

One other thing. If you find that you can’t stop, heading for some deep snow will stop the car fast. You may be stuck, but that is better than hitting something.

14

This is what you want to do, turn the wheel the way you want the front of the car to go. If the car gets sideways and you are looking out the driver’s side window to see what is coming, turn the wheel to the left.
DO NOT HIT THE BRAKES!
The hard part comes next when the rear end starts back around have to start counter steering to the right or you will be looking out the passenger’s side window to see what is coming up next. It may take three or four side to side trips to scrub off enough speed to regain traction and continue in a straight direction.

NO!
This is why when I teach people to drive I never tell them to steer into a skid. I know 2 people who did exactly what you said in your last paragraph and bent the hell out of their cars.
Look assume that the car is rotating clockwise (viewed from the top) Rear end of the car has left the normal 6 o’clock position and is headed for 8 or 9 o’clock. If you were to turn the steering wheel to the right you will only make the car spin faster. This is a bad thing.
Best thing to do is go somewhere snowy and find a snowy parking lot. Go slide your car around for 30 minutes, and you will be good at handling slides. Either that or go find a professional driving school to teach you.

15

Grelby You can slide either end of both RWD and FWD cars. All depends on the power and speed involved.
You can for sure slide the front of a RWD car and the rear of an FWD car I have done both.

16

OK, got it. Turn the wheel the direction I want to go. Just like when I’m not skidding. :wink:

Why can’t people simply say it that way?

17

Beats the living flip out of me.

18

It bears repeating 4WD or AWD =/= bulletproof.

19

Rick you are of course correct - I was oversimplifying for sake of, well, simplicity. A FWD car is more likely to have the front skid, but I have skidded the rear as well. I have very little experience with RWD cars, but I have no doubt that skidding the front wheels can be done in these vehicles. As you say, it depends upon power and speed involved. With your foot off the gas, I would expect that both types of cars are equally likely to have a rear-wheel skid - but are far less likely to skid, period, than when you are accelerating.

What you say about turning the wheel in the direction you want the car to go cuts right through what I was trying to explain in my post. Perfect.