The underpass set to replace the demolished flyover at Ratchayothin intersection will be open by December, two months earlier than its original completion date, Mass Rapid Transit Authority (MRTA) assistant governor Surachet Laophulsuk says.
Mr Surachet said yesterday the MRTA was earlier commissioned by the government to build the underpass to ease traffic woes for commuters during the construction of the Green electric train line's northern extension route -- Mor Chit-Saphan Mai-Khu Khot.
The Ratchayothin flyover bridge was demolished in November 2016 to make way for the Green Line's extension, which will use a skytrain network.
The new underpass at Ratchayothin intersection has been under construction since January last year. Upon its completion, it will be 1,085 metres long and four lanes wide.
It was originally expected to be open for motorists by next February, after incurring about a year's worth of delays due to legal issues, Mr Surachet said.
However, he said new technology used in the construction of the tunnel and renewed efforts by parties concerned will decrease the project's construction time to 24 months, with previous estimates stating it would take a maximum of 30 months to complete.
Kittirat Sroikeeree, an engineer representing the consultant group supervising the construction of the Green Line's extensions, said the underpass walls will be constructed using concrete corrugated sheet piles.
Mr Kittirat said the project is using precast walling to construct the higher parts of the tunnel, to decrease the overall duration of construction and minimise the construction area, which normally takes up more space on main roads.
"Sheet piling for the eastern side is now around 70% complete, and we are sure the same processes will recommence in March, after settlements are made regarding the purification pipes," Mr Kittirat said. "Piling should be complete by May."
The cost of the underpass is 1.2 billion baht, he added.
Pol Col Samreong Suanthong, deputy commander of Metropolitan Police Division 2, said traffic congestion around Ratchayothin intersection has been improving compared to when construction of the underpass began.
"Traffic in the area was virtually in a state of crisis during the demolition of the Ratchayothin flyover," he said.
"With lanes along the roads gradually being returned to motorists, we can see that the roads are starting to clear by around 7pm, so it is guaranteed that the same amount of congestion will not happen again."
Mr Surachet added projects to construct flyovers at Kaset intersection and Sena Nikhom intersection are also set for completion by the end of the year, although the latter is still awaiting an environmental impact assessment study to be carried out.