City Hall plans to build a new four-lane overpass over the congested Na Ranong intersection in order to bypass Bangkok's popular Penang Market.
The existing overpass, which connects Rama III Road to the market, will be torn down and a longer structure built in its place, Thanu Tarakhet of the Public Works Department at the Bangkok Metropolitan Administration (BMA) said on Monday.
That and another flyover that runs from the market to Queen Sirikit National Convention Center will be closed for 900 days from tomorrow, he said.
When the project has been completed, motorists will be able to travel from the convention centre to Rama III directly and vice versa using the overpass, according to Mr Thanu.
Motorists are advised to use alternative routes if possible during the construction period.
Those travelling on Rama III should take Rama IV via Chue Ploeng Road. Motorists from Rama IV can use Soi Suwan Sawat and Soi Sri Bamphen to make their way to Chue Ploeng.
From the Rama IV expressway intersection, drivers can use Soi Suwan Sawat and Soi Sri Bamphen. After that they can take the Nang Linchi and Chan roads to Narathiwat Ratchanakharin Road.
Meanwhile, Prime Minister Prayut Chan-o-cha presided over the opening of a new underpass in the city on Monday morning.
The ceremony for the Ratchayothin underpass was also attended by Transport Minister Arkhom Termpittayapaisith; his deputy, Pailin Chuchottaworn; Bangkok governor Aswin Kwanmuang; and Mass Rapid Transit Authority of Thailand (MRTA) governor Pakapong Sirikantaramas.
The prime minister said the underpass would help boost the flow of traffic, especially now that several electric train projects are under construction.
Gen Prayut also thanked the MRTA for completed the underpass three months ahead of schedule.
Its inbound lanes lead to the Ratchada-Lat Phrao intersection.
The outbound lanes of the underpass lead to Rama VII Bridge.
Prime Minister Prayut Chan-o-cha presides over the official opening of the Ratchayothin underpass on Monday. Pornprom Satrabhaya
The flyover from Penang Market at Na Ranong intersection to Queen Sirikit National Convention Center will be closed for 900 days, starting tomorrow. A new overpass will be built to ease congestion in the area. Varuth Hirunyatheb