Seagull intersection

A seagull intersection or continuous green T-intersection (also known as a turbo-T (in Florida) or High-T intersection (in Nevada and Utah)) is a type of three-way road intersection, usually used on high traffic volume roads and dual carriageways. This form of intersection is popular in Australia and New Zealand, and sometimes used in the United States and other countries.

Seagull intersections get their name from the pattern that the two right-turn lanes make when looking down from the air.

In a seagull intersection, one or more lanes of traffic on the arterial road, on the carriageway opposite the intersecting side road, are free flowing, that is, one direction of traffic on the arterial is allowed to travel straight through without stopping. The free-flowing lane(s) are called "continuous green through lane(s)" (CGTL). For the free-flowing through lanes, access into and out of the side road is provided via turn lanes separated from the through lanes in a configuration similar to exit and entrance ramps at an interchange; however, the turn lanes are at the same grade as both carriageways of the arterial and are located on the same side as the oncoming traffic.

Those wishing to turn right into the side road at the intersection, bear right into the turn lane, which forms one "wing" of the seagull. Here, they meet the opposite carriageway and the side road. Traffic wishing to turn right out of the side road, cross the intersecting carriageway, drive up the other "wing" of the seagull, and merge onto the other carriageway.

For the arterial carriageway adjacent to the side road, access into and out of the side road is ordinarily handled like a conventional T intersection. However, some seagull intersections may have a second, smaller "seagull" formed by two left turning lanes into and out of the side road.

Different methods are used to control traffic where two right-turning movements and the through movement meet. Most intersections use traffic lights, while others use give way (yield) and stop signs, and sometimes roundabouts.

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