The planned ring is approximately 50 km (30 miles) in diameter, similar in size to London's M25 motorway.Started in 1970, the existing segments cover about two-thirds of the circle, under changing names (A104, N104, D104, N184). Construction of the western sections which would complete the Francilienne is currently projected to take place between 2011 and 2015.
The Francilienne is the outermost of the 3 Paris ring roads, enclosing the super-périphérique (A86) and the Périphérique (map on the right).
Enclosing the 3 rings, the very large Grand Contournement (map on the left) would, if the south-eastern portion were to be constructed, provide an outer fourth ring for the planned system of Paris ring routes.<br clear=all/>
Exits are numbered in a clockwise (inner) direction.