Motorists traveling through Reims, France, face significant disruptions beginning Monday, May 18, as the concessionaire Sanef launches a seven-month renovation of a critical underground hydraulic structure beneath the A344 autoroute. The project, centered around the Reims Saint-Remi interchange, will require the closure of two access ramps—a move that will reshape daily commutes, freight logistics, and emergency response routes in the Grand Est region. With an investment of €8 million, the works aim to prevent flooding risks linked to the Rouillat, a buried waterway that has long flowed beneath the city’s infrastructure since the 1970s.
For Xavier Hardy, head of construction at Sanef’s northern division, the decision to proceed with this extensive overhaul stems from decades of deferred maintenance. “The hydraulic infrastructure was built just before the autoroute opened in 1976,” Hardy explained in a statement provided to local authorities. “While the degradation wasn’t urgent, recent inspections revealed structural vulnerabilities that could compromise the flow of the Rouillat—a risk we cannot ignore.” The city of Reims, which has collaborated closely with Sanef and French transport agencies, has emphasized the project’s dual purpose: safeguarding urban drainage while minimizing traffic chaos during peak travel periods.
The closure of the two bretelles—one for northbound traffic and another for southbound—will redirect vehicles through alternative routes, including the Grand Est regional road network and nearby departmental roads. Sanef has committed to maintaining real-time traffic updates via its dedicated portal, though officials warn that congestion could spike during rush hours, particularly for commuters heading toward Reims’ eastern suburbs. The project’s timeline, running from May 18 through December 31, coincides with the city’s busiest travel seasons, including the summer holiday period and the annual Reims Champagne Festival.
Why This Project Matters: The Hidden Risks of the Rouillat
Beneath the surface of Reims’ modern infrastructure lies a relic of the city’s 20th-century expansion: the Rouillat, a small watercourse that once meandered through vineyards before being buried during urbanization in the 1970s. Today, it serves as a critical drainage system for stormwater and agricultural runoff, channeling flows beneath the A344 autoroute through a network of concrete tunnels and culverts. “This isn’t just about an autoroute,” notes Hardy. “It’s about protecting Reims’ underground water management—a system that, if failed, could lead to localized flooding, property damage, and even disruptions to the city’s wastewater treatment plants.”
The current project targets a specific segment of the hydraulic network near the Saint-Remi interchange, where corrosion and sediment buildup have weakened structural supports. Sanef’s engineers will replace corroded pipes, reinforce concrete linings, and install monitoring sensors to detect future leaks. The €8 million budget reflects the complexity of the work: accessing the underground infrastructure requires careful coordination with local utilities, including Veolia, which manages Reims’ water distribution, and Engie, responsible for gas pipelines in the vicinity.
Impact on Drivers: What to Expect Over Seven Months
For the estimated 45,000 vehicles that pass through the Saint-Remi interchange daily, the closures will introduce delays and rerouting. Sanef has identified three primary diversion corridors:
- Northbound traffic: Detour via the D344 toward Bezannes, then merge onto the A4 toward Troyes.
- Southbound traffic: Use the D3 toward Châlons-en-Champagne, then rejoin the A344 at the next interchange.
- Local access: Residents of Reims’ eastern neighborhoods may experience longer routes to the A344’s main lanes, with potential backups at the D344/D3 junction.
To mitigate congestion, the Grand Est regional council has urged drivers to use public transit alternatives, including the Reims Métropole bus network, which will operate extended services during the works. Emergency services, including SDIS Marne fire and rescue teams, have been briefed on the detours, though response times may increase for incidents near the closed ramps.
Commuters concerned about the disruptions can monitor live traffic via:
- Sanef’s real-time traffic map.
- The Waze app, which will flag delays in the area.
- Local radio stations like France Bleu Champagne, which provides hourly traffic updates.
Beyond the Autoroute: How Reims Is Adapting
The A344 renovation is part of a broader push by the French government to modernize the country’s autoroute network, with €30 billion allocated in the 2025–2030 infrastructure plan for similar projects nationwide. For Reims, however, the immediate challenge is balancing construction timelines with the city’s economic needs. “Reims is a logistics hub for Champagne exports,” says Rémi Flament, a spokesperson for the Reims Métropole chamber of commerce. “Any disruption to the A344 risks delays in freight shipments, particularly during the harvest season.”
To address these concerns, Sanef has committed to:
- 24/7 construction zone monitoring to prevent accidents.
- Weekend work where possible to reduce weekday congestion.
- Compensation for businesses directly impacted by rerouting, including fuel stations and restaurants near the closed ramps.
City officials have also launched a public information campaign, encouraging residents to report any unexpected flooding or drainage issues to the Reims municipal services hotline. “This project is essential, but we’re acutely aware of the inconvenience it will cause,” says Mayor Alain Jupin. “Our goal is to ensure that by December, drivers will have a safer, more reliable route—and that the Rouillat continues to serve Reims for decades to come.”
What Happens Next: Key Deadlines and Updates
The next major milestone is the official launch of works on Monday, May 18, with the first phase focusing on the northern bretelle. Sanef will provide weekly progress reports, and the project is expected to conclude by December 31, 2026. Drivers should expect:
- May–June 2026: Partial closures and lane reductions as construction begins.
- July–August 2026: Peak disruption during summer travel; extended public transit services.
- September–October 2026: Final testing of the renovated hydraulic system.
- November–December 2026: Gradual reopening of ramps, with full restoration by year-end.
For the latest updates, visit:
As Reims navigates this seven-month transformation, one thing is clear: the project is more than a traffic inconvenience. It’s a reminder of how modern cities are built on layers of unseen infrastructure—and how their upkeep demands patience, coordination, and a shared commitment to the future.
Have you been affected by the A344 closures? Share your experiences or suggestions in the comments below—or tag @Sanef_Officiel for official updates.