U33 Temporary Sign – Alternating Traffic Section Ahead (Left), 150x120 cm, Class II

U33 Temporary Sign – Alternating Traffic Section Ahead (Left), 150x120 cm, Class II

The left-hand narrowing version of the alternating traffic warning panel: 150x120 cm, the words “Pericol de accidente” (accident danger) and a distance of 400 m, with class II prismatic sheeting.

Why class II

SR 1848-2 requires temporary signs to have at least the same retroreflection class as the permanent signing on that section, so on a road whose existing signs have class II sheeting, a class I temporary sign is not compliant. Class II (RA2) prismatic sheeting returns roughly three to four times more light than class I, and in a work zone, where drivers must slow down and sometimes change lanes, every extra metre of visibility counts.

Where it goes, under SR 1848-1:2024

It goes on roads where a section with alternating one-way traffic, controlled by signs, must be announced. For alternating traffic controlled by traffic lights, the standard has a separate panel, the U34. On this panel the narrowing is on the left, and the distance to the section is 400 m.

What the roadworks rules require (Order 1112/411/2000)

The sign belongs to the advance signing, which is installed first, ahead of the work zone in the direction of travel, with at least 50 cm of clear space outside the carriageway. The rules require signs to be stood on the ground first, to check that they are clearly visible, and only then fixed to a support; no more than two signs go on the same support or side by side, and on one-way roads or bends they can be repeated on the left side or above the road.

For alternating one-way traffic, the rules allow three systems: priority signs, traffic marshals (with paddles such as the V12-20) or traffic lights for automatic control (for example the V11-20 portable lights), supplemented with priority signs. The system is chosen by traffic volume and the length of the section; alternating traffic cannot be organised on a work section longer than 1,200 m, and control by priority signs alone requires visibility between the two ends of the works.

On public roads, works are signed under the methodological rules approved by Order MI/MT no. 1112/411/2000. The road closure or traffic restriction is approved by the road authority, with the traffic police's agreement, on the basis of a signing layout endorsed as final, a copy of which the contractor keeps at the work site. The contractor installs, completes and maintains the signing for the whole job, removes it at the end and restores the original signing; accidents caused by incomplete or missing temporary signing are entirely the contractor's responsibility.

At night, if the existing signing on the road is retroreflective, the temporary signing must be retroreflective too and can be supplemented with flashing or sequential (“cascade”) amber lamps; on main and connecting streets in towns, retroreflective temporary signs are supplemented with flashing amber lamps.

Technical data

• 150x120 cm yellow panel with the words “Pericol de accidente”, the roadworks and road narrows on the left signs, and a distance of 400 m;
• 1 mm galvanised steel sheet, with rounded corners and pressed edges, no sharp edges;
• electrostatically painted;
• class II (RA2) prismatic retroreflective sheeting, with a guaranteed 10-year service life;
• fixings included: 2 clamps for Ø48 mm posts and 4 bolts with nuts;
• compliant with SR EN 12899-1:2007, SR 1848-1:2024, SR 1848-2:2011 and SR 1848-3:2011.

Mounting and size

Fixings for the post are included: 2 clamps for Ø48 mm posts and 4 bolts with nuts; clamps for Ø60 mm posts are available on request. The bottom edge of the sign goes 1.50–2.50 m above the road or kerb, and the edge nearest the road 0.50–2.0 m from the road platform.

SR 1848-2 sets a single size for this panel, 150x120 cm; the class I sheeting version, the same size, is the U33s.