The image shows a segment of a divided highway or a dual carriageway, viewed from above, positioned horizontally.
The divided highway is the road with the highest degree of car traffic separation, through two parallel and unidirectional lanes, travelling in opposite directions and separated by a central reservation.
The two main lanes or carriageways, highlighted by two embossed and parallel rectangles, and crossed by horizontal, blank dashed lines, can only cross each other in allowed areas.
Thus, the two traffic lanes are constantly separated by a median area called a central reservation, which can be represented by a barrier, in the image being marked by a thickened line, consisting of small and horizontally aligned squares.
The frame of the highway, at the top and bottom edge, is highlighted by a thick, horizontal line, on which are aligned small, embossed squares.
Highways have the highest degree of traffic separation, being reserved only for car traffic, with geometric elements that allow the achievement of high speeds and speeds, in safe conditions.
Highways have two one-way traffic lanes, separated by a median area, each with at least two lanes, without level crossings with other traffic lanes and accessible only at certain specially designed points.
Most highways have parking and rest areas, a petrol station, etc.
The first highway-like section of the road was the so-called AVUS (Automobile Verkehrs und Übungs Straße) in Berlin, privately funded and inaugurated on September 24, 1921 as a test and speed track.
In 1924, between Milan and Varese, in Italy, at the proposal of the engineer Piero Puricelli, the first highway in the world was built, the so-called “Autostrada dei Laghi”, which had a single lane in each direction.
In Germany, the first highway was the A555, inaugurated on August 6, 1932, completed with a median area in 1958.
Highways can be classified into three categories: clearing highways that are located in the area of the entrances of cities with particularly heavy traffic; urban highways that are arranged in the interior of cities with values of special traffic flows; connecting highways, also called extra-urban, connect two or more urban centers, they are designed according to the speed of the road, the relief of the region and the traffic capacity it has to take over in the expected perspective period.
Highways must meet certain functional conditions such as: one-way traffic lanes, accidental parking lanes, guide lanes, additional road lanes on sectors with a high ramp and on the entry or exit sectors of the highway (acceleration or exit lanes). deceleration) which are generally carried out instead of parking or emergency lanes, highways must fit as well as possible into the landscape of the region being crossed, have an aesthetic appearance and achieve high optical comfort.
Highways must bypass populated centers, and access to them must be made only in certain places, called road junctions arranged without crossing the traffic flows of one-way roads.