[1] The Sofia ring road is divided into four sections (arcs), at south, north, west and east.

A major part of southern arc has been significantly upgraded in several stages between 2007 and 2012, providing now a conflict-free connection between the Boyana and the Mladost IV junctions.

[1] The segment between Mladost and Tsarigradsko shose blvd / Trakia motorway (A1) interchange has conceptual design since 2015,[2] with a proposal to be upgraded with an EIB loan.

It is a controlled-access highway, designed to carry the transit traffic and supersedes the existing northern arc.

[6] The western arc is completely upgraded to a grade-separated status, between the Lyulin motorway (A6) and the Northern Speed Tangent.