Closure of the Chennevières tunnel on the RN12 in Yvelines, dates of work

The Chennevières tunnel, located on the RN12 near Jouars-Pontchartrain in the Yvelines department, is to undergo a number of works, necessitating its temporary closure fromAugust 2025 to September 2026. Depending on the period, the road will be closed both day and night, impacting many road users who will have to take detour to reach Paris or the rest of France.

The structure leading to the A12 or A86 is being upgraded to bring it into line with 2005 regulations, to improve safety conditions for users of road tunnels.

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The content of the work

This work will enable us to renovate ageing equipment and ensure the robust operation of the tunnel, limiting the risk of future closures due to equipment failure and avoiding disasters. Improvements include

• reinforcement of the tunnel's fire resistance ;
• complete renovation of the tunnel's power supply system;
• repair of damaged acoustic panels;
• closure of aeraulic transparencies (openings in the roof to allow natural ventilation);
• replacement of the lighting with an energy-saving LED system;
• the addition of a new emergency exit and the upgrading of exits for people with reduced mobility (PRM);
• installation of new locking devices and improved signage.

The dates

To limit the impact on users, most of the work will be carried out at night, between 10pm and 5am, between August and December 2025, with an average of 12 night-time closures per month. Deviation routes, signposted, will be offered to users during these closures, on parallel departmental roads to pick up the national highway further on. The province-Paris direction may also be closed from 2:00 p.m. to 5:00 a.m., and the Paris-Province direction from 10:00 p.m. to 2:00 p.m. when lengthening is required.

The tunnel will be closed 24 hours a day during the autumn 2025 school vacations , as well as in winter and spring 2026, and if necessary during the summer of 2026, from Monday to Friday, or occasionally at weekends, to save one year of construction time. To plan your journeys in advance, consult the Sytadin website.

Here is the DiRIF calendar: