A lorry spilled three tonnes of hardcore and has partially blocked a Northampton road.
The accident happened on the Blisworth and Milton Malsor Bypass (which links Danes Camp to the M1).
As a result, there has been queuing traffic southbound at Northampton Services.
There is also congestion to the Danes Camp Way junction, on Upton Way to the Duston Mill Lane junction and on Danes Camp Way itself to the Hunsbury Hill Avenue junction.
Drivers are advised to factor the delays into their journeys.