A mandatory sign states an action that must be carried out. It may require a direction, the side on which an obstruction must be passed, a minimum speed, winter equipment, or the use of a route reserved for particular road users.
A sound interpretation combines shape, symbol, position and supplementary plates. An arrow is read in relation to the point where the sign stands; the pictured user identifies who may or must use a space; a red diagonal bar marks the end of that particular requirement. None of those elements should be read in isolation from lanes and junction layout.
How to recognise and read a mandatory instruction
Mandatory signs are a type of regulatory sign. Many are circular, with a blue background and a white symbol, but the symbol identifies both the required action and the road users concerned: a compulsory-direction sign applies to the vehicles it addresses, while a reserved-route sign is for the category shown and excludes others. ALT-DOGANA, ALT-POLIZIA and ALT-STAZIONE also require a specific action—stopping—even though they have a white background, a red border and black markings.
A requirement normally begins where its sign stands; an advance sign with a distance instead states how far ahead the requirement begins. If the rule continues along the road, it may be repeated after junctions as required. A plate may restrict it to a vehicle class, state its length or exempt certain vehicles. Read the sign, plate and lane to which they refer as one message.
Compulsory direction and advance warning
Straight-ahead, right and left arrows identify the only permitted direction. At the start point they demand the movement shown; bent arrows installed earlier announce a compulsory turn ahead. Advance notice allows time to choose a lane, check mirrors and blind spots and slow down, but does not authorise a turn before the relevant junction.
The arrow requires a manoeuvre at that point; it does not mean that the whole road is one-way. If the requirement applies to one lane, the sign's position above that lane or a supplementary downward arrow makes this clear. If you are in the wrong lane, do not cut across suddenly: follow the permitted direction and correct your route later.
Permitted directions and passing an obstruction
Two arrows show the only alternatives: ahead or right, ahead or left, or right or left. They require neither both movements nor a direction absent from the symbol. The choice must still respect lanes, markings, signals and priority, and must not obstruct a user entitled to go first.
A compulsory-passage sign stands on the nose of an island, central reservation or refuge, or directly on an obstruction. Its downward-sloping arrow shows which side to pass; two arrows allow either side. The requirement concerns only that obstruction and does not require a turn into the next road. Slow down to check the available width, pedestrians and vehicles joining the road.
Roundabouts: direction of travel and priority
The blue disc with circular arrows, installed at the threshold, requires travel around the roundabout as shown. On extra-urban roads a triangular roundabout warning precedes it. The triangle announces the approaching junction; the blue disc prescribes movement on arrival.
The roundabout sign alone does not determine priority. At the entrance, check the GIVE WAY sign, road markings and any other controls; if none are present, the general priority rules apply. Slow down, choose the appropriate lane for your exit in good time, and signal before every lane change and before leaving the roundabout. If you miss your exit, go around again instead of stopping or cutting across lanes.
Understanding a minimum speed
A white number on a blue disc establishes the minimum speed for the road or identified lanes. A vehicle that cannot reach that speed because of its characteristics must not enter the road or lane concerned. The number is not a maximum; the upper lawful speed follows from general rules and separate maximum-speed signs.
A matching disc crossed in red ends that minimum-speed requirement without authorising needless obstruction or cancelling other rules. Congestion, obstacles, poor visibility, weak grip or emergencies may require slowing: no minimum demands an unsafe speed. It limits speed differences in normal flow, while the duty to retain control remains.
Snow chains and winter tyres
The snow-chains sign requires, from its location, travel with snow chains or suitable winter tyres. It is not a weather forecast, and four-wheel drive is no automatic substitute. The requirement concerns recognised devices or tyres fitted and used compatibly with the vehicle.
Prepare before the difficult stretch: check chain size and clearances, know the correct wheels and stop only in a safe fitting area. Seasonal orders may require equipment over stated dates and roads; the roadside disc applies from its location. Even with correct equipment, steer, accelerate and brake gently because grip remains limited.
Routes reserved for pedestrians, cyclists and animals
A pedestrian route is reserved for pedestrians; a cycle track is for bicycles and other permitted cycles. On a shared pedestrian and cycle route, pedestrians and cyclists use the same space and must take particular care around each other. Where a cycle track runs next to the footway, however, the two parts are side by side but separate, and each user must remain in the appropriate part. Another sign reserves a route for saddle or pack animals.
These signs reserve the road or part of it for the pictured class and exclude others unless stated. Cycle and combined-route signs repeat after interruptions and junctions; a red diagonal bar marks their end. The end of a reserved route does not give users automatic priority when they rejoin traffic. Users must still assess crossings, markings and surrounding movement.
ALT signs and obligations for specific vehicles
ALT-DOGANA requires you to stop at customs, ALT-POLIZIA at a police roadblock, and ALT-STAZIONE marks a motorway station at which stopping is compulsory, for example for toll operations. These are neither parking signs nor optional service information. Approach slowly, stop at the appointed point and continue only when the officer, control procedure or system permits.
A direction may apply only to a class, such as goods vehicles over 3.5 tonnes. The vehicle symbol and mass identify its audience; others do not copy that diversion automatically but follow their signs. A plate can state exceptions. Ask three questions: what action is required, where does it begin, and whom does it govern?
Sources and legal references
These references support the rules and principles explained in the chapter.
- Decreto del Presidente della Repubblica numero 495 del 16 dicembre 1992 · Ministero delle infrastrutture e dei trasporti Accessed
- Regolamento di esecuzione del Codice della strada, articolo 104: disposizioni generali sui segnali di prescrizione · Normattiva Accessed
- Regolamento di esecuzione del Codice della strada, articolo 122: segnali di obbligo generico · Normattiva Accessed
- Regolamento di esecuzione del Codice della strada, articolo 123: segnali di obbligo specifico · Normattiva Accessed