A traffic diversion, which will also apply to public transport, will be introduced from November 1st.
Stockholm City Council has allowed three different consultancy firms to examine Slussen, which was opened in 1935. All have discovered that several load-bearing steel girders are in such bad shape that the strength of the structure is at risk.
As part of the diversion, heavy traffic will be limited to certain sections of the junction, although cars and light vans will not be affected.
Repairs are likely to begin early next year.