Road sign R-306: No overtaking for lorries

What it means

«Prohibición a los camiones cuya masa máxima autorizada exceda de 3.500 kilogramos de adelantar a los vehículos a motor que circulen por la calzada, incluso cuando dicha maniobra no implique invadir la zona reservada al sentido contrario de circulación.» RD 465/2025, Annex I of the RGC (BOE-A-2025-12199), Spanish original.

It is aimed at heavy lorries, those over 3,500 kg maximum authorised mass: they may not overtake motor vehicles, even when the manoeuvre is done without leaving their lane.

Where you meet it

You see it on stretches where overtaking by heavy lorries is limited. It applies to lorries over 3,500 kg and is lifted by sign R-503, «End of the no-overtaking ban for lorries». It is lifted by R-503, and also where R-500 lifts all the specific prohibitions.

What you must do

If you drive a lorry over 3,500 kg, do not overtake, not even without entering the opposing lane. The limit is the lorry's maximum authorised mass, not what it carries at that moment: one of 3,500 kg or less is outside it (RGC Annex I, para. 5.5).

Details that count

R-306 belongs, like R-305, to the residual class of «other prohibition or restriction signs» (RGC art. 145.2.d). R-305 looks at the manoeuvre, overtaking by entering the opposing lane; R-306 looks at the vehicle, a lorry over 3,500 kg, and so reaches even a manoeuvre that does not enter that lane. It does not extend to buses or lighter lorries.

What it is confused with

It is confused with R-305, the general ban. R-305 affects all vehicles, but only when overtaking means entering the opposing lane; R-306 affects only heavy lorries. A 12-tonne bus is not subject to R-306.

Related signs

• R-305: No overtaking
• R-503: End of the no-overtaking ban for lorries
• R-502: End of the no-overtaking ban

Studied in topic 23: Overtaking.

Source: RGC art. 145.2.d; RGC Annex I, para. 5.5; RGC Annex I, sign R-306 (RD 465/2025).