Autoroute A12, formerly known as the Autoroute de Bretagne (English: Motorway of Brittany), is a French autoroute located in Yvelines, near Paris. It branches off from A13 (also known as the Motorway of Normandy) at an exchange known as the Triangle de Roquencourt located in the town of Bailly and merges with RN12 and RN10 at Bois-d'Arcy. Its total length is 8.5 km (5.3 mi).