Road sign P-16b: Steep ascent

What it means

«Peligro por la existencia de un tramo de vía con fuerte pendiente ascendente. 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 stretch of road with a steep upward gradient; the figure is the slope as a percentage. It is read by the direction of the inner triangle: pointing up is an ascent.

Where you meet it

It is placed before the climb. A mountain pass is a place where you may find it.

What you must do

On a narrow stretch with no junction or sign, order of arrival decides who goes first; but with a gradient of seven per cent or more, the vehicle going uphill goes first, because restarting uphill is the difficult manoeuvre (RGC art. 63.1). Otherwise, moderate your speed (RGC art. 46).

Details that count

Order of arrival decides in few places, and a narrowing is one of them: there is no junction or sign there to share out the right of way (RGC arts. 60.1 and 62). With a steep gradient the rule changes, as you have seen. And if a sign decides it, the sign rules: at a narrow passage, R-5 takes priority from you and R-6 gives it to you. For the descent there is the twin triangle, P-16a: in both, the figure is the gradient in per cent, never a speed. 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-16a, «Steep descent»: the drawing differs only in the direction of the inner triangle. Do not mistake the figure for a speed disc: a figure inside the triangle describes the terrain; one in a red disc governs speed.

Related signs

• P-16a: Steep descent
• P-17a: Carriageway narrows on the right
• R-5: Priority for oncoming traffic

Studied in topic 10: Vertical road signs.

Source: RGC arts. 46, 60.1, 62, 63.1, 144 to 146; RGC Annex I, sign P-16b (RD 465/2025).