E18 out of Oslo will be narrowed to a single lane this weekend, and the Granfosstunnelen will be closed in the direction of Kristiansand, Statens vegvesen said. The restriction runs from Friday at 21:00 to Sunday at 14:00, according to Dagbladet and VG.
The agency warned of long queues out of the city and urged drivers to leave the car at home.
The cause is work to asphalt and mark the on-ramp where Ring 3 meets E18 at Fornebukrysset. The Granfosstunnelen will still be open to traffic heading to Fornebu.
To avoid a complete stop on local roads, Vegvesenet is asking drivers to follow the signposted detour.
"We again encourage people to leave the car at home, allow enough time, use public transport or choose alternative routes," said Kjetil Fløtre, project manager at Statens vegvesen.