The Bangkok Metropolitan Administration (BMA) is set to pay an estimated 1 billion baht for the expansion of the Saphan Taksin skytrain station, says Transport Minister Arkhom Termpittayapaisith.
The station is expected to be completed by December 2019.
Mr Arkhom said the 27-month expansion plan for the station will be divided into two steps, with the project's design and planning phase first taking five months, starting next month.
The actual construction process is due to start next February.
The expansion plan involves constructing 1.8 metre-wide road expansions on each side of the Taksin Bridge, also known as Sathorn Bridge.
The road expansions will stretch for 230 metres on each side, along the area currently bottlenecked by the Saphan Taksin BTS station.
The station itself will be expanded from a single-track station to a double-track one, prompting the 1.8-metre expansions on both sides of Taksin Bridge, said Mr Arkhom.
He said the planning process will involve discussions on how the expansion of the sky train station can avoid worsening traffic, especially in the bridge's bottlenecked area.
The current bottleneck, located where the Saphan Taksin sky train station is, is widely known to get extremely congested, more so as traffic worsens during rush hour.
Aside from taking cars across the Chao Phraya River, Taksin Bridge is also a popular stop for commuters to transfer to the Chao Phraya Express Boat service at Sathon Pier.
BMA deputy permanent secretary Wanchai Thanomsak said the estimated one-billion baht cost of the expansion plan will also involve reorganising the areas surrounding the Saphan Taksin skytrain station.
He said the area is currently home to an disorganised station for motorcycle taxis and song-taew as well as several tangled electricity lines.
Mr Wanchai said reorganising this area will be necessary due to tourist traffic.
Surapong Laoha-unya, director and COO of Bangkok Mass Transit System Plc, which operates the skytrain, said the Saphan Taksin BTS station will still be open for operations during the expansion to minimise inconvenience for commuters.
But he said the BTS will have to discuss with the BMA, the Ministry of Transport, and the Department of Rural Roads how the construction plans will accommodate the regular train service.
The expansion is expected to ease commuter congestion on the Bang Wa-National Stadium route. The Rural Roads Department earlier approved the expansion of the riverside station, originally designed with a small platform and single rail track, allowing it to take up more space on nearby Taksin Bridge.
During the construction phase the trains will not stop at the station, leaving officials to figure out how the BTS will help passengers who usually use Saphan Taksin station -- an important transport hub for those using ferries and express boats along the Chao Phraya River.
A shuttle bus service could be provided to move passengers to and from the nearest station.