LATEST: Preston city road collapse
The council started emergency repairs on a section of road on Ring Way at the junction with North Road after a sinkhole suddenly appeared on Tuesday, October 3.
Council workers believe the problem started after a leak from a damaged drain washed away ground that supported the road.
A spokesman for Lancashire County Council said: "Further investigation of a damaged area of road has revealed a problem with a drain which has washed away an area of ground supporting the road.
"We've had to close one lane at the top of Ringway to access the area and make repairs, which is causing some delays, however all turning movements at the junction are still available.
"We're working as quickly as we can to complete the repairs and are working towards being able to fully reopen the junction later this week."
A spokesman for Preston Bus said on Tuesday: "We have been informed by Lancashire County Council's Highways Operations Engineering team that emergency road works are taking place in Preston, due to a severe road collapse.
"Traffic is already building up and all services crossing the city and Ring Way are likely to be adversely affected, especially at peak times.
"If you are driving it would be prudent to avoid the area."