Autoroute A12, formerly known as the ''Autoroute de Bretagne'' ( en, Motorway of
Brittany
Brittany (; french: link=no, Bretagne ; br, Breizh, or ; Gallo language, Gallo: ''Bertaèyn'' ) is a peninsula, Historical region, historical country and cultural area in the west of modern France, covering the western part of what was known ...
Yvelines
Yvelines () is a department in the western part of the Île-de-France region in Northern France. In 2019, it had a population of 1,448,207.A13 (also known as the Motorway of Normandy) at an exchange known as the ''Triangle de Rocquencourt'' 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). Access is free.
It has not been lengthened since its construction, which makes it the oldest French motorway to have remained on its original route.
History
Its history started in 1934 with the publication of ''Plan Prost'', which envisaged a network, already dense, of motorways in
. The A12 was then known as the "Autoroute de Bretagne", which is a reference to its proximity to the nearby RN12 route which extends to Brittany. Its construction began in 1936 with the first deforestation on the site of the ''Triangle de Rocquencourt''. Work ceased at the outbreak of war in 1939, with only earthworks having been executed. Work began again in the post-war period and lasted until 1950.
The motorway has not undergone any significant changes since that time. The changes that have occurred include the covering of a section at the
Saint-Cyr-l'École
Saint-Cyr-l'École () is a commune in the western suburbs of Paris, France. It is located from the centre of Paris.
It used to host the training school for officers of the French army, the École spéciale militaire de Saint-Cyr (ESM), which wa ...
and the widening of the roadway to four lanes in one direction and three in the other. It is on this motorway that one of the first automatic radars in Yvelines were installed.
There are plans to extend the A12 in the medium-term (2015–2020) up to
Ablis
Ablis () is a commune in the Yvelines department in north-central France.
History
During the Franco-Prussian War, when a German unit moved to take Ablis on October 7, 1870, they were ambushed and routed by about 1,500 French militia soldiers who ...
and the A11. It is anticipated that the route will go around the town of
Trappes
Trappes () is a commune in the Yvelines department, region of Île-de-France, north-central France. It is a banlieue located in the western suburbs of Paris, from the center of Paris, in the new town of Saint-Quentin-en-Yvelines.
Transport
T ...
. Beyond that point, the existing highway N10 will be reused.
This project, started back up in 2004 by the transport minister
Gilles de Robien
Le vicomte Gilles de Robien (; born 10 April 1941) is a French politician and former government minister.
The son of Count Jean de Robien by his wife Éliane Le Mesre de Pas, he is descended from the noble Breton family de Robien.
In 1989, ...
, caused significant concern among locals, such as the inhabitants of South of Yvelines. They object as they feel that this new section of highway will introduce transit of heavy lorries between the A10/A11 motorways and the western A86 tunnel (Rocquencourt), with traffic predictions as high as 100,000 vehicles per day. Others object to the extension crossing the Haute Vallée de Chevreuse Regional Park. A public consultation was organised in 2006.
In October 2006, following public consultation from March to June 2006, the Minister announced the choice of a 15 km long extension by median route 2C', comprising five interchanges and several covered trenches. This route provides for an extension that begins in a tunnel at the end of the current motorway, at the junction with the national road 10, then runs along, partially covered, Montigny and the
Trappes
Trappes () is a commune in the Yvelines department, region of Île-de-France, north-central France. It is a banlieue located in the western suburbs of Paris, from the center of Paris, in the new town of Saint-Quentin-en-Yvelines.
Transport
T ...
business area and crosses, partly in a covered trench, the communes of
La Verrière
La Verrière () is a commune in the Yvelines department in the Île-de-France in north-central France.
Population
Transport
La Verrière station is served by Transilien trains to Paris and Rambouillet.
Education
Preschools and elementary scho ...
and
Le Mesnil-Saint-Denis
Le Mesnil-Saint-Denis () is a commune in the Yvelines department in the Île-de-France region in north-central France.
Demographics
Schools
The commune has two public preschools, Maternelle de Champmesnil and Maternelle du Bois du Fay, as w ...
, and ends by bypassing
Les Essarts-le-Roi
Les Essarts-le-Roi () is a commune in the Yvelines department in the Île-de-France in north-central France.
Geography
Les Essarts-le-Roi is bordered by Coignières and Lévis-Saint-Nom to the northeast, Dampierre-en-Yvelines to the east, S ...
from the west to join the RN 10 at the interchange with the RD 191. However, while this motorway project had been included in the ''Schéma directeur de la région Île-de-France'' (SDRIF) since 1965, it was withdrawn in its 2013 version.
List of junctions
{, class="plainrowheaders wikitable"
, -
!scope=col, Department
!scope=col, Location
!scope=col, km
!scope=col, mi
!scope=col, Junction
!scope=col, Destinations
!scope=col, Notes
, -
, rowspan="4", Yvelines
, rowspan="2", Montigny-le-Bretonneux
, 0.0
, 0.0
,
, Montigny-le-Bretonneux
, Southbound exit only to N10 West
, -
, 1.3
, 0.8
,
, Northbound exit N12 east only / Southbound exit N12 east & west
, Bois-d'Arcy / Montigny-le-Bretonneux / Saint-Cyr-l'École
, -
, rowspan="1", Bois-d'Arcy
, 2.4
, 1.5
,
, Bois-d'Arcy / Saint-Cyr-l'École
, Northbound entry only / Southbound exit only
, -
, rowspan="1", Bailly
, 8.5
, 5.3
,
, Caen / Rouen / Paris
,
, -