The strade extraurbane principali ("main extra-urban road"; : strada extraurbana principale) or type B road, better known as a "superstrada", are a type of roads of Italy defined within the Italian Highway Code.
Therefore, compared to motorways, roads of this type have some technical differences (for example the minimum width of the emergency lane but not of the travel lanes), the color of the signs (blue background instead of green), the speed limit for cars and motorcycles (), the radius of curvature, the presence of the emergency lane and the presence of SOS columns. For transit on main extra-urban roads, unlike many motorways, there is currently no toll system, except for the Pedemontana Veneta.
The circulation of the following vehicles on the autostrade and roads referred to in paragraph 1 is prohibited:
The movement of pedestrians and animals is prohibited, except for service areas and rest areas. In these areas animals can circulate only if duly guarded. Pedestrians are only allowed to pass along the emergency lanes to reach the emergency call points. On carriageways, ramps, junctions, service or parking areas and in any other motorway area it is prohibited:
These restrictions are the same as those that apply along Italian motorways. Roadside assistance is permitted, as along motorways, only to authorized companies. Furthermore, the circulation of pedestrians and animals is only permitted within the service areas and rest areas.
On strada extraurbana principale, the speed limit for cars, motorcycles and trucks with a laden mass not exceeding is , unless otherwise indicated, for buses with a laden mass between and and for trucks with a laden mass between and it is , for trucks with a higher laden mass to and for vehicles towing trailers it is . For other categories of motor vehicles, the limit is lower and depends on the type of vehicle.
The strade extraurbana principali do not follow a specific nomenclature; they are classified administratively as Italian state roads, Italian regional roads, Italian provincial roads or Italian municiapal roads. Therefore, some state, regional, provincial, municipal roads may have sections technically classified as strade extraurbana principali (type B road), others as strade extraurbane secondarie ("secondary extra-urban roads; type C road) and still others as urban roads (type D and E roads).
Along the strade extraurbana principali the background of the road signs (both of the indication signs and for example of the mileage signs panels) are blue, therefore not different from the signs installed along the strade extraurbane secondarie.
In other European states, what in Italy are known as the strade extraurbana principali, roads with separate carriageways with two or more lanes in each direction, without at-grade intersections, are not classified as highways, but in different ways. For example: