Drivers on the A4 motorway in Seine-et-Marne will need to watch their route, especially in the evenings. From May 18 to June 25, 2026, Sanef will stage several overnight closures between exits No. 12 Ferrières-en-Brie and No. 13 Serris, as part of the work on the future Sycomore diffuser in Bussy-Saint-Georges. Both directions will be affected, but on different dates.
Concretely, the initial closures will affect the Paris to Reims direction. The A4 will be closed at night from May 18 to May 22, then from May 26 to May 28, from 10:30 PM to 5 AM. Drivers will be required to exit at the A4/A104 interchange. The entry ramps toward Reims from the A104 and Ferrières-en-Brie will close as well from 9:30 PM. To rejoin the highway, follow the detour to the Serris junction. The Ferrières service area will also be closed from 6 PM to 5 AM during these nights of work.
The month of June will alter the flow of disruptions. From June 15–19, and again from June 22–25, the A4 toward Paris will be closed at night, between 11:30 p.m. and 5 a.m.. Traffic must exit at the Serris interchange. Access to Paris from Serris and Val d’Europe–Jossigny will be closed from 10:30 p.m.. As elsewhere, a detour will allow motorists to reconnect with the A4 at the A4/A104 interchange. The Bussy-Saint-Georges service area will also be inaccessible from 6 p.m. to 5 a.m..
These closures remain in effect, subject to potential construction-related delays. For night-time journeys, it's wise to check traffic conditions before you head out, notably through Sanef updates, Sytadin, or Sanef radio at 107.7.
They form part of the work on the future Sycomore interchange, the new highway junction planned between Ferrières-en-Brie and Val d’Europe-Jossigny. This new phase is designed to modify the signage and the safety systems linked to the development of the A4.
The project is designed to better serve the Bussy-Saint-Georges area, notably the upcoming ZAC de la Rucherie, located to the south of the highway. According to Sanef and EpaMarne, this business district is expected to attract new economic activity and generate more than 3,000 jobs in the long term.
Outside of nightly closures, the A4 won’t be completely shut down. Traffic will continue on three lanes, but with narrower lanes and a speed limit of 90 km/h in the work zone. In other words, even during the day, the stretch between Ferrières-en-Brie, Bussy-Saint-Georges and Serris will require a little more attention than usual.
For drivers in Île-de-France, the message is straightforward: plan ahead. A nighttime trip to Marne-la-Vallée, Reims, Paris, or the eastern part of the region may take a few extra minutes, or call for a revised route. On the A4, until the end of June, the night is dominated by roadworks.
This page may contain AI-assisted elements, more information here.
