(LANAUDIÈRE, QUEBEC, CANADA) – A section of Quebec’s Autoroute 40 has been closed westbound near Saint Cuthbert after a cavity was found beneath the road, forcing authorities to divert traffic and prepare a temporary traffic arrangement on the opposite carriageway.
The affected section, about 60 kilometres from Montreal, was closed as a precaution on Wednesday after the discovery of a hole beneath the roadway. The closure covers about 5 kilometres of the A40 and will remain in place for an undetermined period while transport authorities assess the structure.
The Quebec Transport Ministry announced the closure at 7:01 a.m. Traffic is being diverted through montée Saint Laurent and Route 138. Authorities warned that congestion is expected in the area as vehicles are redirected away from the closed section.
Transport officials are working to establish traffic in the opposite direction on the eastbound carriageway, which has not been affected by the cavity. The arrangement is intended to maintain a westbound route while work is carried out on the damaged section.
The cavity was found beneath a structure known as a culvert, raising concerns about the stability of the road surface. The Transport Ministry said the temporary traffic arrangement would be put in place as quickly as possible.
The closure adds to a history of infrastructure problems along the A40 in the region. On Aug. 26, 2025, a 14 kilometre section of the westbound highway between Berthierville and Lanoraie was closed for five weeks after a culvert collapsed.
A more serious incident occurred in 2005, when an entire section of the A40 collapsed near kilometre 208 east of Trois Rivières. The earlier failure demonstrated the potential disruption that structural problems beneath the highway can cause to one of the region’s main transport routes.
The latest closure also draws attention to the condition of culverts managed by Quebec’s Transport Ministry. Statistics obtained by Radio Canada in 2025 showed that the Laurentides Lanaudière region had about 6,600 culverts under provincial responsibility, with 24.4% classified as being in poor condition.
Across Quebec, the ministry was responsible for about 62,000 culverts, of which 15.9% were considered to be in poor condition.