Night Rain, Spray, and a Light Steering Wheel
You are eastbound at 100 km/h on a four-lane divided highway posted at 100 km/h. It is 23:00 and rain has been falling for an hour; there is standing water in the wheel tracks and a heavy spray plume behind a transport truck 30 metres ahead of you. Your wipers are on high, the defroster is running, and the inside of the windshield is beginning to fog at the edges. Without warning the steering feels light and the tachometer climbs slightly while your speed stays the same. Headlights from a vehicle behind you are bright in your mirror.
1. What is happening to the car, and what is the correct first response?
Read the worked answer
Diagnosis: The tyres have begun to ride up on a film of water instead of the pavement - hydroplaning. The light steering is the front tyres losing contact; the tachometer climbing while road speed holds steady means the driven wheels are spinning slightly with no grip to push against.
First response, in order:
- Ease off the accelerator smoothly. Do not lift abruptly, which shifts weight forward and can unsettle a car with almost no grip.
- Do not brake hard. Hard braking on a water film locks wheels and turns a straight-line slide into a spin.
- Do not steer sharply. Hold the wheel straight and steady; the car will follow the water until speed drops enough for the tread to bite again.
- Wait for grip to return, then correct gently.
Why this order: Everything you do at the moment of loss of contact is amplified because the tyres cannot transfer force. The only reliable fix is to let speed fall.
2. Looking back, what were the two mistakes in your following distance and lighting setup?
Read the worked answer
Following distance: 30 metres at 100 km/h is roughly one second of gap - and that is measured to a truck throwing a spray wall. The dry-road minimum of about two seconds is a floor, not a target. In heavy rain and spray at night, four seconds or more is the realistic figure, which at 100 km/h is over 100 metres. That gap is what gives you room to see, and room to react without hard braking on a low-grip surface.
Lighting: Low beam is correct and you should stay on it. High beams reflect off rain, spray and fog straight back at you and make things worse. If your headlights are aimed high or a fog light is on, you are adding to the glare.
The third issue: Fogging at the edges of the windshield means the defroster is losing the fight. Interior fog scatters oncoming headlights and wipes out your view of the lane lines - fix it with the defroster and fresh air before it spreads.
3. The truck ahead brakes hard and the vehicle behind is close on your bumper. What do you do?
Read the worked answer
Do not answer a close follower with a hard stop on a wet road. Braking as hard as possible on a surface where you have just lost contact is how a following-distance problem becomes a pile-up.
Sequence:
- Brake progressively - build pressure rather than stabbing at it, so the tyres load up gradually and the car behind gets a clear, early signal.
- Turn on your hazard lights briefly to warn the following driver you are decelerating sharply.
- Leave yourself an out: know whether the shoulder or the left lane is empty before you need it. A panic swerve into an occupied lane is worse than braking in your own.
- Once stopped or slowed, increase the gap ahead so you are not trapped if the truck stops completely.
The judgement point: The closer vehicle behind you reduces your braking options, while the truck ahead reduces your time. Both squeeze you toward the same answer - slow early, signal early, and keep a lane of escape open rather than reacting at the last second.