Corrugation and Vibration

Unpaved roads develop corrugation — regular washboard ripples across the surface, formed by traffic over time. They produce a continuous vibration through the whole vehicle, and two consequences matter.

Steering becomes imprecise. The vibration transmits into the steering, so the wheel is constantly being nudged and your inputs land less exactly than they would on smooth tarmac. The response the curriculum gives is to hold the wheel firmly — firmly enough that the road can't move it, not so rigidly that you can't steer smoothly. Loose hands on corrugation means the road is steering as much as you are.

And the tyres spend time not fully touching the road. This is Steering, Suspension & What Failure Feels Like made vivid: on a rippled surface the suspension is working constantly to keep the tyres pressed down, and where it can't, grip momentarily drops. Corrugation therefore reduces both braking and cornering grip, on top of the loose-surface effect already described — and a vehicle with worn shock absorbers is markedly worse here, because the wheels skip rather than follow the surface.

Speed is the lever, and the instinct is wrong. Many drivers find that going faster over corrugation feels smoother — the vehicle skims the tops of the ripples instead of following them. It genuinely feels better, and it's genuinely worse: skimming means the tyres are in contact with less of the road, so grip falls exactly when the vibration is disguising how little you have. The comfort is a signal you're losing contact, not gaining it.