Winter Weather Accident Avoidance Tips
By Eric Peters, Automotive Columnist
Just a few square inches of rubber at each of your car’s four corners is all that keeps you on the road. It’s pretty amazing when you think about it. Several thousand pounds of steel, plastic, glass and you — all kept under control by four small “contact patches” of tire tread.
Now imagine what happens when you drive over slick, ice-covered surfaces. On a curve, the car will try to keep on going straight ahead — and right off the road. Inertia keeps it going in that direction — and the lack of traction prevents you from being able to make corrections.
If you are on a straight stretch that’s covered with black ice and you tap the brakes (even if you have ABS) sudden weight transfer could cause the car to go into a sidewise slide. Often, the only thing that will stop it is an impact with some fixed object, like a tree or telephone pole.
It’s best to avoid driving at all in icy conditions, of course — but sometimes we can’t help being caught in a storm. Here are some practical driving tips to help avoid getting into an accident when the weather turns wicked:
* Reduce speed –
Even if you have four-wheel-drive or all-wheel-drive, your vehicle’s ability to stop/slow down on ice and snow is no better than any other car’s. And you’ll need more room to come to a stop on wet/snow/ice-slicked roads than you would on dry pavement. By dropping your speed, you also reduce the amount of time/space you’ll need to safely come to a complete stop — and increase your odds of avoiding an accident.
* Increase your following distance –
In winter weather, double or triple the distance between yourself and the vehicle ahead of you. This will give you more time to slow down — and more time to consider worst-case alternatives (such as steering into a grassy field rather than piling into the car ahead).
* Avoid oversteering and abrupt, jerky movements of the wheel –
Change directions gradually and smoothly. Abrupt lane changes or sudden steering inputs can throw the weight of the car around and that could be just enough to overcome whatever little traction you’ve got — resulting in a spin-out or slide. Try to anticipate the need to slow down for for traffic signals, make turns and so on.
* Braking –
If the car has ABS, push the brake pedal to the floor as hard as you can. The system will keep the wheels from locking up and you will still be able to steer the car. If you own an older car without ABS, you should depress the brake pedal gradually and smoothly, but not all the way down. If you sense the wheels about to lock up, back off the pedal to avoid putting the car into a skid. The goal is to “threshold brake” — which means simply applying maximum pedal effort just short of lock-up.
* Controlling speed on slick surfaces -
If you have a manual transmission, downshifting to a lower gear uses the “engine braking effect” to keep speed under control on downhill stretches without over-using the brakes — which may cause them to heat up excessively and fade when you really need them. If your car has an automatic transmission, you can achieve the same effect by turning off the overdrive (usually there is an “O/D” button on the shifter) or putting the selector lever into the next lowest gear down from “Drive.”
* Use momentum to your advantage -
In other words, keep moving — if it is safe to do so. While it’s important to obey traffic laws, sometimes common sense overrides rigid adherence to rules. For example, if you are driving in a snowstorm and there’s a stop sign at the top of a hill with several cars coming up behind you, it’s not necessarily the smart move to come to a complete stop and risk either getting stuck or, worse, sliding back down the hill and hitting the cars behind you. Assuming you can clearly see the intersection and there are no other cars attempting to come through, a “rolling stop” in such circumstances might be safer than risking the loss of your traction and forward momentum.
* How to deal with slides and skids -
When a rear wheel drive car loses traction, typically the back end of the car will start to “fishtail.” If this happens, gently back off the gas and attempt to regain control by steering in the direction of the skid. Often, just backing off the gas will cause the car to stop fishtailing — and the tail will snap back into line. Avoid the temptation to hit the brakes in a skid; this will often only make the situation worse. Try to gently steer your way out of it — and try not to panic. Many late model cars have electronic stability control technology that will greatly assist you here.
Front-wheel-drive cars are usually better in the snow and ice than rear-drive cars because all the weight of the engine and transmission are on top of the drive wheels. This gives better traction and makes the car less apt to spin its wheels than a rear-drive car. All-wheel-drive is even better in this respect.
*Make sure you have decent tires –
“Mussolinis” (bald tires) or high performance summer tires (which are almost as bad as baldies in snow and ice) should be avoided. All-season tires are ok, but for maximum grip (if you live in a part of the country with serious winter weather), the small hassle of switching over to specific-use snow tires for winter driving is a smart move. A set of four snow tires is a lot cheaper than a totaled car.
* If the worst happens -
If you find yourself in a situation such as a skid that you can’t control or steer out of, try to plan your impact to minimize the damage to yourself, others and your vehicle (in that order). For example, you may have enough time and enough control left to choose what you will hit. If possible, go for something with “give” — such as a snowbank or grassy ditch. If possible, try to hit it sideways, rather than head-on, as this will lessen the severity of the impact. You can use small trees and bushes to slow your vehicle down, too.
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Here’s a free winter driving hazards video that make be a great review before getting on the slick roads this year
http://www.safetyskills.com/winter-driving
Hello Eric,
Great post! A lot of drivers are not prepared to drive in bad weather conditions, that’s why at Fox Rent A Car Blog we also wrote a post sharing tips to stay safe on the road during winter time. We like to give travel and driving advice to help travelers get the best vacations.
thanks agin for your post.
FWD cars don’t only benefit from the weight on the front/drive wheels, but also because there is no fishtailing effect when too much power is applied to the drivewheels. Of course, this causes “understeer” but that is deemed to be safer than spinning around… for those who can’t simply handle RWD cars. Fact is, RWD is “better” if you know what you’re doing, because there, two wheels are used for steering “only” and two other wheels are used for power… this distributes the “work” amongst all 4 tires, rather than making the fronts do “everything”.
Lastly, AWD/4wd isn’t necessarily better than FWD. In fact, if you let off the gas in my Subaru, you are pretty much guaranteed to spin it. Most AWD cars will do this, because you are starting to fishtail under-power (ie, the rears have already lost traction)… suddenly engine-braking with the rears will continue to leave the rear wheels without traction, allowing the car to spin. For this reason, it’s important to know what YOUR car will do in such situations… my subaru requires maintaining some throttle, so that the AWD system can “do it’s job” and keep the car in-line… you just have to have a little faith that the system will do its thing.
That being said, most “AWD” cars like Honda CRVs and such are 90/10 distribution, by default… they are pretty much FWD cars for the most part, and so they *may* not suffer from this problem. Audi, Subaru, and other more evenly distributed AWD systems will continue to have this problem.
4WD is a different animal still…
This is of little use since most cars at least have fwd but in rear wheel drive vehicles adding a couple of hundred pounds or so in the trunk will reduce fishtailing many times. It is like driving a different vehicle. I did not see this in the article but rear wheel drive cars or trucks are dangerous to drive without extra weight in the back on snow and ice.
I also disagree with the advice of using the engine to slow the vehicle on slick surfaces. The brakes have far greater control of slowing you down on slick surfaces unless of course the road is not that slick then the engine braking is fine.
Most modern cars, anything with in the last ten years, have drag torque regulation built into the engine/transmission controller.
In non traction limited situations, adding extra mass to be accelerated, 100 lbs of ballast, does add extra traction but cancels itself out in regards to acceleration potential.
In situations where you are traction limited [snow/slush] It does help to get the vehicle into motion. But the vehicles that benefit usually has abysmal traction to begin with [rear drive pickups 55/45 weight distribution, '4x4' pickups 60/40]
George I was not talking about traction starting up when adding the extra weight. I was talking about fishtailing when at driving speed whatever that speed is. I have not driven the vehicle you are talking about so I do not know how much adding weight affects it in almost ice conditions but I do know the older rear wheel drive vehicles have far far less fishtailing even if you floor it and spin the tires. There is less fishtailing with weight added. This article is talking about safety and it is not talking about starting from a dead stop.
I doubt if you have ever driven such vehicles in poor conditions because all you do is read and dream about such vehicles.
Yes adding extra weight in the rear will increase traction, reducing [or eliminating] wheel slip which improves lateral traction in dynamic situations.
Crappy rear drive cars: Ford Crown Victoria & Mercury Grand Marquis, Ford Mustang (though that has improved in the last generation, and newest one)
If you drive a 50/50 weight distribution (or better) rear drive car, you don’t need to add ballast to improve winter mobility.
also rear drive cars can benefit from a torque sensitive rear differential, if the driver uses the throttle judiciously.
(neighbor traded in his jag for a cayman, if he gets the winter tires I suggested I better some seat time)
Don’t forget the Nissan 370Z & Hyundai Genesis coupe: 55/45
and the long departed Chevrolet Caprice & Camaro (both were terrible)
The worst car is the supercharged Mustang GT500 58/42 (and Edmunds tested a tuned one at 59/41-that is a front drive weight distribution)
The Miata has improved from 55/45, by virtue of packing on the pounds over the last twenty years. Didn’t it start under 2000 lbs for the lightest model?
All I’m saying is that the statement “FWD is better” and “4WD is better still” is not quite true.
George: Yes, many newer automatics have less drag because they coast/unlock… I guess I’m too used to my manual trans. I believe an auto in manumatic-mode might still introduce a decent amount of drag.
The point is – 4WD/AWD only works for getting moving (as you mentioned)… the problem is usually turning and stopping. This is where 4/AWD drivers get too over-confident, in thinking that they have more traction than everyone else – they don’t. As the article states, and I have said many times myself – we ALL have 4-wheel braking and (almost all) have 2-wheel steering… so just because you have 4/AWD doesn’t mean you should be driving faster than everyone else.
All cars have four wheel steering.
It is an old hillbilly saying regarding rear drive cars, that the front tires steer and the rear tires push.
If the rear wheels did not steer, then as soon as you initiated a turn [with the fronts] the rear wheel will continue in a straight line, and you have just oversteered your vehicle.
The rear tires drive & steer, if you are slipping the rears, the lateral traction decreases. High slip rates and the lateral stability almost completely goes away.
Modern throttle by wire manual shift transmissions have drag torque regulation too.
The recommendation on engine braking found in the article is quite correct. Anything that actively acts on the wheels, say for example, disc brake pads, can cause wheel lock-up. In situations with reduced traction, such as on snow and ice, the point at which the wheels lock requires much less active force to reach.
Engine braking is passive braking. Even with no downshifting, letting off the throttle causes engine braking; downshifting only increases the effect. Since there is no direct force that acts on the wheels, there is no possibility of wheel lock-up.
I utilize engine braking quite a bit when the snow gets deep. I get down to about 10 miles an hour and let the discs take over from there. That, and allowing more following distance, has kept me out of accidents in the winter.
Himura your engine braking may be fine in deep snow when it is not slick but brakes, particularly anti-lock brakes are much better for slowing you down and avoiding skids. With engine braking you have zero control except for selecting different gears or using the clutch.
I fogot to say that engine braking for the most part does not lock up the wheels but they can cause the wheels to slip from the pavement when the engine braking force is more than the traction you have on the pavement. Engine braking can cause the wheels to lock if you also have some braking force applied and you hit an icy patch. All of your braking force then goes to killing the engine and thus locking up your drive wheels . If it is icy or close to it put your vehicle in neutral and use your anti-lock brakes to slow down.
George – I was simplifying the statement that all cars have front-wheel steering. Bottom line is AWD and FWD and RWD cars have the “same” steering systems, so they turn the same. I don’t want to get into an unrelated disucssion on which wheels do the steering.
As for modern TBW (throttle-by wire) systems on manual cars, my 2005 Subaru Legacy is certainly a “modern” car, and has TBW… and does no such thing as “regulating” drag torque. You let off the throttle, the car will drag significantly… and if you’ve already started an oversteer condition, then you will spin out. I know this is the case with AWD Audis a well. Manuals don’t manage this, unless, maybe, if they have some traction-control or yaw-control system on them. My car does not have either of these, nor do I need them, because I know how to drive.
Himura: True, braking can be “overapplied” to cause wheel lockup, but if the road is slick enough, so can engine braking. Engine braking is certainly not (usually) as strong as an applied brake, but that doesn’t mean it can’t happen. Engine braking can lock up wheels too… and what’s worse, when this happens, ABS is not able to “help” so if one wheel slips, the car could go into a spin. Engine braking makes sense when you don’t want to over-heat the brakes… otherwise, pedal-braking is still the better option.
Randy was correct in his last two statements, which is what I just repeated…
Normally I just let Randy spout off stupid stuff, but
“If it is icy or close to it put your vehicle in neutral and use your anti-lock brakes to slow down.”
No. Shifting into neutral earns you nothing, and could help contribute to an accident.
James you are showing your lack of ice experience. I have had dozens of hours of experience on ice. Where do you live in the south? Everything I have posted is the truth and from real experience not guestaments. If you want to verify the information I am sure you can find supporting documents on the internet.
If you apply your brakes when you are on ice you have a dead engine.
Randy is right.
He wasn’t referring to a traffic situation, or a steady state throttle braking scenario. [downhill]
If you are coming to a stop, what does it matter if you put a manual shift transmission in neutral [clutch up], or just put in the the clutch [declutch]?
There is slightly less drivetrain inertia when you are in neutral, so if you have a ‘fast’ ABS system [again anything made in the last ten years] you should have slightly better braking by shifting into neutral.
Schwinn, that is not a drag torque regulation problem, that is a lack of stability control system or suspension issue.
If you are oversteering, and in the slight transition time while undergoing a load reversal, the rear suspension can not regain lateral grip then, you are going to continue oversteering, but that is what you want, right? [got countersteer?]
and to think the only Subaru with the 35/65 planetary differential was the WRX STi, and then only here for a very short time before being replaced with a slightly less rear biased differential (41/59 I think)
Too bad Subaru never brought over the EZ30R with the 6 speed manual.
Yeah, actual rear wheel steering is few and far between.
Throttle braking is highly unlikely to actually fully lock a wheel. It can exceed your traction limit.
Not exaclty what I meant George. Below is just one of the links I found. It is wrong though in that even with antilock breaks it is possible to kill your engine.
http://en.wikibooks.org/wiki/Transwiki:Manual_transmission_driving_technique
Stalling due to loss of traction while braking
When decelerating, a driver will apply brakes and then disengage the clutch shortly before stopping (around 1000 RPM in 1st gear or somewhere above “walking speed” as above). In normal conditions with good traction, this is fine. However, on some surfaces, and depending on the severity of the braking, without an Anti-lock Braking System, the wheels can lock up. This can happen easily on slippery surfaces like snow, ice and loose gravel. The poor traction on such surfaces can prevent the momentum of the car from turning the wheels, which leaves the engine as the only real force for the brakes to oppose.
The rest of what I was talking about engine braking:
http://en.wikipedia.org/wiki/Engine_braking
Applications
Engine braking passively reduces wear on brakes and helps a driver maintain control of the vehicle. Active use of engine braking (shifting into a lower gear) is advantageous when it is necessary to control speed while driving down very steep and long slopes. It should be applied before regular disk or drum brakes have been used, leaving the brakes available to make emergency stops. The desired speed is maintained by using engine braking to counteract the gravitational acceleration.
Improper engine braking technique can cause the wheels to skid (also called shift-locking), especially on slippery surfaces such as ice or snow, as a result of too much deceleration. As in a skid caused by over-braking, the vehicle will not regain traction until the wheels are allowed to turn more quickly; the driver must reduce engine braking (shifting back up) to regain traction.
Randy – were you just talking about manual cars? Because I was imagining newbs out there shifting their automatics into neutral and… bad things.
You have a point for manuals (I’d say clutch-in instead of shift, but same difference), but I won’t say that people in automatics should shift into neutral and back.
James I was on ice almost 30 years ago which was rear wheel dirve and an automatic where it was so icy that to stay on the road I did have to shift it in and out of neutral and keep well under 10 mph. That is not normal driving though and I do not know how a modern car with front wheel drive would handle on such a surface. I would think much better with possibly only needing to use brakes to keep that slow.
I never keep my clutch in for an extened period of time which can happen on slight hills. There might be reasons to do that in some cases though particularly if you feel if you think it may help you pull out of a skid.
I agree with James – telling people in automatics to put it in neutral while braking is a bad idea. In a manual, it’s easy to clutch in, and that’s fine… but the blanket statement of “neutral” is a bad idea, since most people (and probably the people this article is geared towards) drive automatics.
As for the engine-braking argument, I think we agree, George, you CAN reach traction limits with engine-braking… and that was my point. I’ll agree it’s not going to happen a lot, and less so in an automatic, but it can happen, and then you’re in worse trouble because ABS can’t do its thing. For this reason, I’d recommend pedal-braking first, since it’s safer… UNLESS you’re dealing with long-term braking (ie, downhill) where you may need engine braking to prevent fade.
Yes you can exceed the traction and start a skid, albeit with a low slip rate, but you can’t fully lock the wheels.
And this is where drag torque regulation come in. BMW’s SMG 1 system had this a long time ago.
In a Road & Track article, November 1996, Paul Frere describes how the drag torque regulation works. ‘For example, the message that the rear wheels are revolving slower than the front wheels is instantly recognized by the gearbox electronics and communicated to the engine’s control unit, which immediately opens the throttle slightly, allowing the rear wheels to maintain their grip.’
On page 4 ‘Finally, Engine Drag Torque Regulation (MSR) prevents
the driven wheels from locking should the accelerator be lifted suddenly or the vehicle braked sharply because a low gear is engaged.’
http://www.volkswagen.ie/templates/volkswagen05/images/brochures/Touareg_Sports_Utility_Vehicle.pdf
Now lesser vehicles [lacking stability control] can still get into trouble if there is operator error.
An experiment, say you are in 3rd gear roughly 15 mph and you downshift into 1st gear [manual shift transmission] and then let the clutch out without revving up the engine. That can exceed the traction and start a skid, and would be very deleterious to your health if you did that in a curve.
Fun weather today.
George it does not matter if you locked your wheels or not when you are sitting in the ditch or in an accident. It also does not matter what kind of brakes or control systems you have installed in your car, if you are driving too fast for conditions nothing will help you. If you rely on such systems to keep you safe so you can drive faster then you are making a mistake.
George: Gotcha… I see how traction/stab control systems can do this. Again, since none of my cars have had it, I have never experienced it. In a large-displacement motor, with a manual, I imagine this is pretty useful… not many large displacement manual cars out there…
Randy: You always seem to think that everyone here is out to speed recklessly… wtf? No one here says to do this.
As for “depending” on things… we all “depend” on various parts of the car – brakes, for example. Are you saying we should never drive above 5mph, just in case the brakes give out?
Schwinn I have seen people try to drive the speed limit or more on snow packed roads. Is the speed limit 5 mph? I never said anyting about 5 mph but 65 mph or more on snow packed roads is crazy. I am sure you have seen such drivers unless you live in the south. What I am saying is that if you hit an icy patch at such speeds nothing will help you. If you are trying to stop on an icy road your stopping distance goes up a dozen times.
Randy to make his appearance to condemn Mr Peters for encouraging drivers to run stop signs (anarchy!) in 5…4…3…
Brother John, at least he did not recommend speeding up before the stop sign.
What I cannot figure out is why this article is on this web site. It recommends “Reduce speed”. That is not like this web site to post an article with such recommendations.
The article also said “By dropping your speed, you also reduce the amount of time/space you’ll need to safely come to a complete stop — and increase your odds of avoiding an accident.”
That statement just is not possible. Everyone that I have heard from on this web site said that speed has nothing to do with avoiding accidents.
It is just a good thing I was driving slower coming home from work tonight because I missed a deer by about 15 feet. I had my dims on because of a car a couple of hundred feet in front of me and cars coming the other direction so there is very little warning of a deer crossing the road from your left to your right. 10 mph faster and I would have hit it. Of course speed has nothing to do with being able to avoid accidents.
Speed has nothing to do with people to people interaction caused accidents [inattention, stupidity, contempt]. This is the uncertainty of weather/environment.
I forgot that Randy has x-ray vision to see under through the snow, so you can know if there is ice on the pavement.
Randy, winter weather driving is different than 80 degrees and sunny and dry. We’re not stupid, we’re not going to go 100 mph on a back road with snow or a highway with snow for that matter.
Chances of finding a deer on say a highway is slim to none. I’m not going to drive 55 on a sunny interstate highway thats dry and .0001% of an animal crossing it. high speeds are safe in certain conditions, obviously not in rain or snow. You have a better chance of your tire blowing out.
Here is a headlight upgrade for your Focus
http://www.rallylights.com/detail.aspx?ID=133
or you could look for the headlights from an SVT Focus.
George it has nothing to do with what type of headlights. If you have your dims on to prevent your car from blasting oncoming traffic and cars ahead, your vision ahead is also decreased. I guess you like to blast other drivers away though.
Randal as for people slowing down when there is snow on the pavement then why is it that I see people fly past me on the highway and later see them in the ditch? For you and others here it is all about pushing the limits. You or others here push their limit on driving drunk, driving fast on the highway or school zones and blowing past stoplights a few seconds after they are red along with driving too fast in rain and snow.
George, added speed along with your ” inattention, stupidity, contempt ” causes death.
No, dual beams stink. One reflector for both low beam & high beam?
and the rest of that does not deserve a response.
Ok George how many hundred feet ahead of you would your low beam headlights show a dear standing or coming from your left when the contrast between the road and the deer is very little?
What do you say about these articles?
http://www.nhtsa.dot.gov/staticfiles/DOT/NHTSA/Traffic%20Injury%20Control/Articles/Associated%20Files/deadly.pdf
http://www.ou.edu/oupd/nightdr.htm
Both of those links assumes only 0.53g deceleration. Maybe for a semi-tractor trailer, but that is grossly underbraked for a normal car.
and the distance vision is crappy sealed beam headlights range.
I always turn off the high beams way before I encounter an oncoming vehicle, or slower vehicle ahead.
I think the intelibeam automatic high beam system should be banned.
Randy, I don’t you have seen an isolux plot of good headlights. You get more light to the sides (where the deer are) and for distance vision.
or you can just upgrade the wiring to/from the bulb [make your own wiring harness]. Ford is notorious for undersized wiring.
“as for people slowing down when there is snow on the pavement then why is it that I see people fly past me on the highway and later see them in the ditch?” because you aren’t the least competent driver on the road.
Ok George those may be conservative numbers but you do not always have perfect dry and clean road surfaces and determining if you should stop or not can vary significantly at night because of less than perfect lighting conditions no matter what headlights you have. If you think you can see good enough in front of you with your low beam headlights to be able to see an animal on the highway and be able to stop from 75 mph good for you. You may be the only person.