This re-organisation was part of a renaming of primary highways managed by the Generalitat de Catalunya.

It is a partially tolled autopista which runs parallel to the southern Barcelona's Mediterranean coast.

It connects several relevant towns such as Vilanova i la Geltrú, Sitges and Castelldefels, as well as it passes close to the Barcelona-El Prat Airport.

The middle section should correspond to the actual autovía B-20, also known as Ronda de Dalt, which is a part of the Barcelona's Rondes (ring road).

It begins at the intersection of the middle section (B-20) with the C-31, at Montgat, and finishes at Tordera, from where Blanes can be reached by road.