Black Ice on the Morning Run to Fredericton
You leave Saint John at 6:20 a.m. in January for a 110 km drive to Fredericton in a front-wheel-drive sedan. The outside temperature on the dash reads 0 °C. Freezing drizzle has been falling since 5 a.m. and the highway looks merely wet. The car has all-season tires with about 3 mm of tread left, matched front and rear. Traffic is moderate at the posted 100 km/h, and a transport truck 40 metres ahead is throwing up a fine spray that keeps freezing on your windshield, so the wipers chatter and smear. Your hands are tight on the wheel. About 25 km in, the spray from the truck suddenly stops and its brake lights come on; at the same moment the steering feels strangely light.
1. What do the icing wipers and the sudden loss of spray tell you, and what should you do in the next few seconds?
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Freezing drizzle at 0 °C with wipers icing up means the air is at or below freezing and the road surface is very likely at or below freezing too. The "wet" look is the trap: a thin film of water over ice looks exactly like a wet road, and it offers almost no grip.
The sudden end of the spray is the sharper warning. A truck's tires throw water only while the surface is wet; when the spray stops while the truck is still moving, the surface ahead has very likely changed to ice or the truck has reached an untreated shaded section. Brake lights at the same moment confirm the driver has felt or seen something.
In the next few seconds, smoothly:
- Ease off the accelerator; do not brake hard.
- Turn off cruise control if it is on.
- Open the gap immediately, from 40 metres to much more.
- Turn on full headlights so you are visible, and run the defroster so the windshield clears.
- Feel for grip with a gentle, brief brake application on an empty stretch, never while close behind the truck.
If the surface is ice, the next exit is a reasonable destination.
2. How should speed and following distance change, and why does the posted 100 km/h not settle the question?
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The posted limit is a maximum for good conditions, not a target. It says what is legal on a dry road in daylight; it says nothing about what is achievable on ice with 3 mm of all-season tread.
Speed has to be set by the distance you can stop in and the distance you can see. On ice, stopping distance can be several times the dry figure, so 100 km/h buys you a stopping distance far longer than the gap you have. Practically, that means slowing to a speed where you could stop within the space ahead that you know is clear, and where a slide, if it happens, is a low-speed event rather than a violent one.
Following distance: at least four seconds in these conditions, and more behind a truck, whose spray destroys your view and whose stopping distance is far longer than yours. Double the normal two-second gap is the minimum, not the goal.
One more point: the speed of the traffic around you is not evidence of a safe speed. Other drivers on the same ice are simply taking the same risk - or they have better tires.
3. The car begins to slide sideways. Walk through the inputs you make.
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The order matters, and none of it is instinctive.
- Ease off the accelerator. Lifting smoothly transfers weight forward and reduces the driving force that is asking the front tires for more grip than exists. Do not lift abruptly - that has the same effect as braking.
- Do not brake hard. Locked or heavily loaded tires cannot steer. If you have ABS and genuinely must slow, press firmly and hold; the pedal pulsing is normal, and you keep steering.
- Look and steer where you want to go. Your hands follow your eyes. If the rear has stepped out, steer into the slide - turn the wheel in the direction the rear is travelling - and be ready to unwind quickly when the car regains grip, because it will snap back.
- Make one smooth correction, then a second small one if needed. Sawing at the wheel through a slide usually makes it worse.
- Once straight and slow, pull off at the next safe place and reassess whether to continue. A slide is information: the road has told you what your tires can do, and 3 mm of all-season tread in freezing drizzle is not enough for another 85 km.