One side of Lindum hill has been closed until further notice due to a collision on the junction.
The incident was reported to Lincolnshire Police at 10.12am, where a young male cyclist and a pedestrian were involved in a collision.
The incident happened on the junction between Lindum Hill and Monks Road.
The pedestrian is believed to have sustained serious injuries, and was escorted to Lincoln County Hospital.
The 15-year-old cyclist was not badly injured in the incident.
Until further notice, Lindum Hill southbound has been closed off.
Lincolnshire Police are appealing for witnesses to contact them via the Lincolnshire Police Collision witness Hotline on 01522 558855.
Update @ 12.20pm: Lindum Hill both directions are now passable.
Update @ 16.03pm: The 37-year-old male pedestrian from Lincoln is being transfered to the Hallamshire hospital in Sheffield, due to his serious condition.
The cyclist does not require medical treatment. Lincolnshire Police interviewed him about he incident and sent him home.
— This is a developing story.