The Ratchayothin flyover will be closed to traffic in 10 days from now and dismantled to pave the way for the construction of the traffic tunnel instead.
Construction of the tunnel will take two years.
Acting commander of the traffic police division Pol Maj Gen Jirasant Kaewsang-ek said police will close the flyover to traffic from November 22-26 and all vehicles previously using the flyover will be diverted to other roads instead.
He said demolition of the flyover will start November 27.
During the two-year traffic closure, motorists using the flyover as main travel route are advised to take Lat Prao, Lat Prao-Wang Hin, Soi Chokechai 4, Suthisarn, Kaset-Nawamin, Vibhavadi, and Sirirat expressway instead.
For motorists wishing to avoid the Ratchayothin intersection, they are advised to take Phahonyothin road and enter Soi Ratchadapisek 48, 46/1 and exit to Soi Phahonyothin 35 or access to Ratchadapisek 46 and exit to Phahonyothin road.
But for inbound traffic from Phahonyothin road, motorists are advised to turn left using Ratchadapisek road to Rama 9 but drive into Soi Phahonyothin 30 and exit at Soi Ratchadapisek 36.
However if motorists are driving from Vibhavadi- Phahonyothin, they are advised to take Soi Vibhavadi 30 and exit at Phahonyothin 21, or take Vibhavadi 32 and exit at Phahonyothin 23.
He added that the traffic notification was aimed at telling motorists and the people to learn how they could avoid the interaction so that they could plan their travel in advance to ease the inconvenience that will be expected during the traffic closure and tunnel construction.