Road sign P-16a: Steep descent

What it means

«Peligro por la existencia de un tramo de vía con fuerte pendiente descendente. La cifra indica la inclinación de la pendiente en porcentaje.» RD 465/2025, Annex I of the RGC (BOE-A-2025-12199), Spanish original.

It warns of a steep descent and carries the gradient as a percentage. The figure describes the terrain and does not tell you how fast to go down.

Where you meet it

You meet it before the descent. If a panel with metres sits beneath it, that figure is another matter: it measures the distance remaining, while the number inside the triangle is the gradient.

What you must do

Moderate your speed before descending, not during: the triangle triggers the duty to moderate under article 46 without giving you a numeric limit (RGC arts. 144.1 and 46.1). The figure you see does not say how fast to go.

Details that count

If you are going downhill and meet an uphill vehicle on a narrow stretch with a steep gradient, order of arrival does not rule: once the stretch has a gradient of seven per cent or more, the uphill vehicle goes first, because restarting uphill is the difficult manoeuvre, whereas on a level narrowing order of arrival does rule (RGC art. 63.1; arts. 60.1 and 62 by contrast). And like every class P sign, it flags a risk that is hard to see in time and imposes no speed (RGC arts. 144 to 146).

What it is confused with

It is confused with P-16b, «Steep ascent». The P-16 pair is read by the direction of the inner triangle: pointing down is a descent, pointing up is an ascent. The figure is also confused: inside the triangle it is terrain, in a panel below it is distance and in a red disc it is speed.

Related signs

• P-16b: Steep ascent
• P-17a: Carriageway narrows on the right
• P-14b: Dangerous bends, the first to the left

Studied in topic 10: Vertical road signs.

Source: RGC arts. 46.1, 60.1, 62, 63.1, 144.1, 144 to 146; RGC Annex I, sign P-16a (RD 465/2025).