The motorway, 170 km long, cost a total of € 650 million. It is dual-carriageway both ways on its entire course and service areas are positioned at regular intervals. It is toll free.
The motorway was built with a special road surface to allow rain water to run off quickly, but it is ineffective with snow that often falls in large quantities in winter, so snowplows are employed regularly. Motorway traffic radio 107.7 broadcasts A84 information specifically.
The A84 currently stops at Avranches. A dual carriageway is used as a bypass around Avranches by the west. This road cannot be upgraded to motorway standard due to its layout. A new motorway bypassing Avranches with three lanes is planned, as well as a further extension to Nantes by upgrading the RN 137, a dual carriageway between Rennes and Nantes.