Intersection Design
Introduction
A road intersection refers to those elements of road and transportation infrastructure where two or more roads intersect.[1] These infrastructures allow users to exchange between roads. The crossing of roads can occur with a level intersection or with an uneven intersection. It is important to note that this term can also refer to elements of other transportation systems, such as railways or bicycle paths.
Terminology
When talking about level road intersections, it is common to refer to the road section that enters the conflict zone with the term access. The conflict zone is the sum of the areas where the trajectories of the different possible movements intersect. Movements refer to the possible destinations that a vehicle can choose entering the intersection. In general there are four types of movements: right turn, direct movement, left turn and “U” movement. Very often at-grade intersections have exclusive right or left turn lanes, in order to increase the capacity of the intersection and to avoid blocking other vehicles by those who are waiting. This is known in Spain as flared because it is a widening of the regular section of the road when reaching the intersection that resembles a horn.
At-grade intersections
Controlled intersections
As intersections mean that vehicles traveling through different accesses can meet simultaneously (implying the risk of collision), at-grade intersections require some type of control so that they can operate safely. There are different intersection control codes and systems that prevent the simultaneous use of vehicles in conflicting movements. The most frequent are Stop / Stop, yield and traffic light.
Below are some signs that allow you to define the rules for operating at the intersection:
Within the level intersections, there is also the roundabout or roundabout. Unlike the previous ones, it works in a circular movement in which the vehicles inside the roundabout have priority, so technically and under normal conditions all the roads or tracks that reach the roundabout have the same preference.