City Hall's multi-billion-baht Kiakkai Bridge project faces fierce opposition from architects and university scholars, who see it as an eyesore that will also present security concerns for the new parliament building nearby.
Their concerns prompted the Association of Siamese Architects on Wednesday to petition Deputy Prime Minister Prawit Wongsuwon, who chairs a committee overseeing the 16-billion-baht project, urging him not to proceed with it.
It was not just a request for a review, "we want to see it scrapped", association president Ajaphol Dusitnanond said.
He said a thorough study of the project -- a road link that is part bridge and elevated road stretching 9.5 kilometres -- led his group and landscape experts to reach several unfavourable conclusions.
They concluded it lacked beauty, would fail to meet present needs and would present possible threats to security at the new riverside parliament.
Construction of the parliament complex is expected to be completed later this year.
Regarding the security aspect, "the bridge would be near Thaharn Road", said Kwansuang Atibhodhi, an urban planner and a guest lecturer at Chulalongkorn University's Faculty of Architecture.
"This will lead to potential risks if political demonstrations take place there," he said.
Both the parliament and the bridge project are in the Kiakkai area which is known to house many military units.
Mr Kwansuang urged City Hall to re-consider the plan because "if it makes the wrong move, problems will erupt and the consequences will exist forever", he said, adding the bridge's large and rough structure would spoil the river view.
The bridge was originally planned to ease travel to and from the Bang Sue area, once eyed as Bangkok's new transport hub. But after the State Railway of Thailand, which oversees land development in Bang Sue, decided to scale down its own project, the bridge became unnecessary, according to Phanit Phuchinda, head of Chulalongkorn University's Urban and Regional Planning Department.
This bridge will also not be connected to the city's ring roads and has narrow access and exit points, so it will not benefit traffic flow much, he said.
People will also be able to reach Kiakkai and nearby areas via the two new Blue and Purple line extensions, Mr Phanit added.
The Blue Line elevated track passes Charansanitwong Road while the Purple Line will have Kiakkai Station on its route, which links Bang Sue and Rat Burana.
"We're not opponents of the government, but we feel we must give useful advice and offer different points of views for better decision making," Mr Ajaphol said.