Core: Bridge and tunnel: side wind, the bridge light, and the tunnel emergency procedures

On bridges and viaducts you can suffer from side wind, especially outside the built-up area on high bridges and above large open water — a sign with a wind sock (J31) can announce this (Book p.97). Those same locations become slippery faster than ordinary roads in frost, because the wind also passes underneath and cools the road surface faster. The bridge light itself has one simple rule: if the red light is burning OR flashing, you stop, switch off the engine, and wait until the light is extinguished (Book p.97) — the state of the light (steady or flashing) makes no difference to your behaviour. At a tunnel, three signs inform you in advance: L13 shows the tunnel length, but only for tunnels longer than 250 metres; C22 with a letter indicates which dangerous substances may not pass through; K14 then points out the diversion route for those substances (Book p.98). Right before the tunnel you switch on your dipped headlights — well in advance, not only inside the tunnel, otherwise drivers behind you think you are braking — and take off any sunglasses (Book p.99). In case of breakdown in a tunnel you first try to get out of it; if that fails, you park as far right as possible, switch on the hazard lights, and walk — never crossing the carriageway — along the tunnel wall in the direction of traffic to the nearest emergency post (Book p.99-100). In case of fire in your own vehicle you park as close as possible to the wall, switch on the hazard lights, never turn around and never reverse, leave the key in the ignition, and leave the tunnel on foot via the nearest emergency exit (Book p.100).