What it means
The S-1a sign indicates a dual carriageway. It informs you that you are entering a road intended for fast, separated traffic, with its own rules on access, lane use, U-turns, and admitted users according to the general regulations and the signs present. It is usually placed at the beginning of the dual carriageway or at accesses from conventional roads and links. When you see it, adapt your driving to a road with a higher relative speed, joining with observation, sufficient acceleration, and respect for existing priority. In the test they often use it to distinguish a dual carriageway from a motorway, a conventional road, or a simple direction sign.
- CategoryInformation signs
- ShapeRectangular or square, blue
Practise DGT questions featuring this sign
Ten DGT 2026 exam-style questions about signs, with an explanation after each. Free, no signup.
Variants of family S-1
Other related signs
S-347
An immediate-exit destination toward a service zone, area, or road with an exit shared toward a motorway or dual carriageway
S-348A
A destination sign within a diversion
S-348B
A variable destination sign
S-350
An overhead sign on a conventional road for an immediate exit toward a conventional road
S-351
Placed over the carriageway on a motorway or dual carriageway and indicates an immediate exit toward a conventional road
S-354
An overhead sign on a conventional road for an immediate exit toward a motorway or dual carriageway
S-355
Placed over the carriageway on a motorway or dual carriageway and indicates an immediate exit toward a motorway or dual carriageway