Road sign R-400c: Mandatory direction (arrow straight ahead)

What it means

«La flecha señala la dirección y sentido que los vehículos tienen la obligación de seguir.» RD 465/2025, Annex I of the RGC (BOE-A-2025-12199), Spanish original.

The sign is a mandatory one and the arrow shows the direction and way vehicles are obliged to follow. R-400c is the one with the arrow pointing ahead. With a single arrow, the sign leaves no room: that direction is the only one permitted.

Where you meet it

You see it at a junction. The regulation classes it among the mandatory signs: it imposes a compulsory rule of traffic, the direction of the arrow (RGC art. 145.2.e).

What you must do

Go straight on. Users must obey a sign even if it seems to contradict a general rule: the specific beats the general, and that is exactly what a sign is placed for (RGC art. 132.2). Only special circumstances that justify it exempt you from obeying.

Details that count

With several arrows the sign changes name and logic: R-403 means the «only directions and ways permitted», and its arrows show the only things vehicles may take (RD 465/2025 catalogue). With one, as in R-400c, there is no room for your own judgement: it is a mandatory sign and the arrow does not advise, it orders (RGC art. 145.2.e).

What it is confused with

It is confused with R-400a, same official name and another arrow, and with the sign that permits several directions (R-403). With a single arrow that is the only permitted direction; with several, you have more than one. It is also confused with R-402, which marks the rotation direction inside a roundabout.

Related signs

• R-400a: Mandatory direction (arrow to the right)
• R-402: Mandatory direction at a roundabout
• R-500: End of prohibitions

Studied in topic 10: Vertical road signs.

Source: RGC arts. 132.2, 145.2.e; RGC Annex I, sign R-400c (RD 465/2025).