Visibility in the roundabout

Scale 1:100 (meters)

Users who approach a roundabout must perceive the vehicles with priority within the crown in time to change their speed to give way or possibly stop. In particular, in order to ensure adequate visibility, the following requirements must be adopted:
 

• the observation point is located at a distance of 15 m from the stop line coinciding with the edge of the outer circumference;
• the planimetric position is on the center line of the roundabout entrance lane (or of the entrance lanes) and the observation height is 1 m on the road level;
• the area for which complete visibility is required corresponds to the quarter of a round crown located to the left of the access channel considered.

Construction of the visibility area to be guaranteed in the roundabouts.

As regards the perception of the roundabout, it is recommended to create a central island of overhead rotation or with clearly visible inclined edges: for this purpose it is possible to use plantings or earthen fillings as elements of arrangement and furnishings such, however, from do not compromise correct visibility. It is however necessary to keep a crown free from any type of visual obstacle (shrubs, …) of a width of 2 m measured from the inner edge of the crown that can be surmounted or from the peripheral edge of the central island (in the case of roundabouts with central island insurmountable).

The insertion of visual obstacles on the directional islands is absolutely to be avoided.

To increase the perception and "legibility" of the roundabout, all the elements connected to it
(directional island and central island) should be visible at least 250 m away from it. Readability can also be reached by excluding:
 

• a approach configuration in curves and counter-curves;
• a central island of non-circular shape;
• an irregular width of the ring;
• a transversal inclination of the turning platform oriented inwards;
• a presence of planting on the arms near the graft on the roundabout, as it can give the illusion of continuity of the itinerary.

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