The closure in both directions on 28 September will allow further inspections to take place into the flaws, which include issues around internal supports, barriers, bearings and drainage.
The two-lane, concrete flyovers were opened in 1970 as part of the US$3.13-million Mersey Tunnel relief scheme. Following legislation on major highways structures a post tension site investigation began in 2016 to assess the northern and southern sections, both of which are over 240m in length.
The flyovers, consisting of two separate roads linking Lime Street to Dale Street (south flyover) and Tithebarn Street (north flyover), run directly behind the city’s museums and galleries in William Brown Street.
In a statement, Liverpool City Council said the flyovers had been under constant assessment since the 1980s when they were closed for repairs. There were further remedial works in 2005 and 2013 as part on an ongoing maintenance regime.
Liverpool City Council anticipates the new survey - which will include the removal of the road surface and drilling into the decks as well as underground assessments of every supporting column - will take at least six months to complete.