Tema 36: rain, fog, snow and tunnels in the DGT exam

Bad weather and tunnels change three things: which lights you use, how fast you go and how far you need to stop.

Reviewed on 6 October 2026 · sources: BOE and DGT

Bad weather and tunnels change three things: which lights you use, how fast you go and how far you need to stop.

In tunnels, underpasses and S-5 stretches you keep your lights on at any hour. You overtake only with two or more lanes (carriles) in your direction and no sign banning it; length does not matter.
You use lights according to visibility, not the clock, by day too in fog or heavy rain. The rear fog light only in dense fog or similar.
Your speed must let you stop within your field of vision. Wet: worse grip and braking, more distance.
The DGT manual teaches that a bridge freezes before the adjoining stretches.

Watch out: S-990a and S-990b show the direction and distance to the nearest emergency exit; S-980, its location.

In DrivingLingo: study the warning signs, review night driving and speed, then practise with the .

Source: RGC art. 98.1; RGC art. 87.1.d); RGC art. 106; RGC art. 105.1; RGC arts. 45 and 54.1; DGT manual (teaching, not statute)

Key rules of topic 36

In tunnels, underpasses and S-5 stretches you keep your lights on at any hour.

Well-lit tunnel: position and dipped. Dark tunnel: like an unlit road, main beam unless it could dazzle.
Wider than 2.10 m: gauge lights too.
You overtake only with two or more carriles (lanes) in your direction and no sign banning it; length does not matter.

You use lights according to visibility, not the clock, by day too in fog or heavy rain.

Front fog light: in poor visibility or on roads of 6.50 m or less with a bends sign. Rear: only in dense fog or similar.
Stopped at night or in poor visibility: position lights; by day and in good visibility, not.

Your speed must let you stop within your field of vision; at night, that field is what the beam reaches.

Insufficiently lit road: either you cannot read a plate at 10 m or you cannot see a dark vehicle at 50 m.
You dip even if the other driver does not: the duty is not reciprocal.
Wet: worse grip and braking, more distance; in aquaplaning the tyre floats on water.

Snow chains go on the driving axle and on both sides.

S-21 (passability of a mountain pass or section): shows the passability status of the pass or section named at the top of the sign. Read that panel before you climb.
P-19: slippery road; moderate your speed.
Clear «black ice» looks like water, and a bridge freezes before the adjoining stretches.

Study topic 36 step by step: the rule, its citation and exam-style questions.