Road sign S-3: Road reserved for motor vehicles

What it means

«Indica el principio de una vía reservada a la circulación de automóviles.» RD 465/2025, Annex I of the RGC (BOE-A-2025-12199), Spanish original.

It marks the start of a road reserved for motor vehicles. It is an information sign: it tells you where that road starts, it does not give you an order.

Where you meet it

You see it where the reserved road begins. Its end is marked by S-4, «End of road reserved for motor vehicles». In the motorway series, S-1 is a motorway, S-1a a dual carriageway, S-2 and S-2a their ends, and S-3 the road reserved for motor vehicles (official sign catalogue, RD 465/2025, definitions of S-1 to S-4).

What you must do

If your vehicle is not among those the legal definition admits, do not enter that road. The definition of «road reserved for motor vehicles» is in Annex I of the consolidated traffic law, concept 68 (TRLSV Annex I, def. 68).

Details that count

Each sign in the series has its own end: S-2 marks the end of a motorway, S-2a the end of a dual carriageway and S-4 the end of a road reserved for motor vehicles (RD 465/2025 catalogue). Learn the start and end pairs: the start switches a regime on, and the end switches it off. The three starting signs, S-1, S-1a and S-3, are information signs.

What it is confused with

It is confused with S-1, «Motorway», because both are reserved for one type of traffic. They are not the same road: a motorway has separated carriageways and no level crossings and is reserved exclusively for motor vehicles, while S-3 has its own legal definition (TRLSV Annex I, def. 68). And it is not S-51a, which reserves a lane, not a road.

Related signs

• S-1: Motorway
• S-1a: Dual carriageway
• S-51a: Lane reserved for specific types of vehicle

Studied in topic 31: Motorways and dual carriageways.

Source: TRLSV Annex I, def. 68; RGC Annex I, sign S-3 (RD 465/2025).