⛏ RN 12 | Works between Ploumagoar and Plouisy

Updated on 20/08/2026

⛏ RN12: Three months of works between Ploumagoar and Plouisy

#### Traffic will be modified until 10 November

⚠️ The West Interdepartmental Road Directorate (DIR) will carry out major renovation works on the RN12, in both directions, between Ploumagoar and Plouisy, crossing the municipalities of Ploumagoar, Guingamp, Grâces, and Plouisy, from Monday 24 August to Tuesday 10 November 2026.

Conducted in several phases, this operation aims to permanently improve safety, driving comfort, and traffic flow.

Throughout the entire duration of the work, traffic will be maintained via traffic reversals, but significant delays are expected, particularly during morning and evening peak hours.

The works include:

• the renewal of the roadway across the entire affected area, as well as on the ramps of the Tolmine, Grâces Z.I., and La Chesnaye interchanges;

• the widening to two lanes of the exit ramp from the Kernilien interchange, heading toward Lannion, to facilitate merging and improve traffic flow;

• the replacement of 1,250 meters of safety barriers on the central reservation with more robust concrete barriers;

• renewal of vertical signage and road markings;

• replacement of joints on a bridge structure.

#### ☑️ Traffic maintained, but adjusted during construction

To allow work to proceed while maintaining traffic on the RN12, traffic will be temporarily diverted to the opposite carriageway in several phases.

The provisional schedule is as follows:

• From 24 August to 18 September: traffic heading toward Brest will be redirected to the opposite carriageway, over approximately 6 kilometers. The slip roads between the interchanges of La Chesnaye and Kernilien will be closed, except for the exit from La Chesnaye, which will remain open.

• From 21 September to 9 October: Traffic heading toward Rennes will be diverted to the opposite carriageway, over approximately 3.5 kilometers between Kernilien and the Z.I. de Grâces, with closure of ramps located on this section.

• From 12 October to 4 November: Traffic heading toward Rennes will be diverted to the opposite carriageway, over approximately 4 kilometers between the Z.I. de Grâces and La Chesnaye, with closure of the affected ramps.

• From 5 to 10 November: The left lane will be closed in the direction Saint-Brieuc to Brest to complete the work.

Significant delays are expected, particularly during morning and evening peak hours.

#### ⏱ Detours and real-time traffic information

Detour routes will be put in place for motorists affected by the closure of access or exit ramps.

To enable road users to anticipate their journeys, illuminated information signs will be installed near the construction site.They will display real-time traffic conditions and any difficulties encountered in the area, allowing motorists to plan their route in advance and avoid delays.

#### ☝ Safety: Let's all remain vigilant!

Works are organized to ensure the safety of staff and road users, while minimizing inconvenience as much as possible. Drivers are asked to respect temporary signage, speed limits, and safe distances. Extra caution is recommended when approaching the site.

Every day, DIR staff work on the roads to keep you safe—respect their work, respect them.

#### ℹ️ To stay informed

• Check traffic conditions on the DIR Ouest website: diro.fr;

• Follow road information via Bison Futé: bison-fute.gouv.fr;

• Pay attention to illuminated information signs along your route.