Commuters on the BTS Silom line are likely to face continued congestion and delays until the green light is given to demolish Saphan Taksin station, one of the network's top officials says.
Anat Arbhabhirama, chairman of the Bangkok Mass Transit System management committee, said the station was imposing major capacity constraints on the entire line and a solution needed to be found as soon as possible.
The two main options that the BTS has put to the Bangkok Metropolitan Association are to knock down the station completely, or to move a section of the King Taksin Bridge to allow room for a second rail line to be built. The second option would be considerably more expensive and time consuming.
Commuting on the Sukhumvit line during peak hours is easy and predictable, Mr Anat said, while BTS management has been struggling to handle rising passenger numbers on the Silom line.
Mr Anat said trains on the Sukhumvit line run every two to three minutes in peak hours and six to nine minutes off peak. During rush hours on the Silom line, however, trains only arrive every four minutes. Mr Anat said the sole cause of the delay is Saphan Taksin station.
The station has only one platform, which must serve trains going in both directions. Because the station is wedged in a narrow gap between two elevated roads, there is no room to expand it or add a second platform.
If the station were demolished, however, a second rail line could be built, allowing more frequent services along the entire Silom line. Saphan Taksin was only ever meant to be a temporary station and was due to be demolished as soon as the Silom line extension was completed.
But as the extension was hampered by lengthy construction delays, Saphan Taksin station's proximity to the Chao Phraya River meant it became one of the network's most important commuter hubs. "What happens now is that one train has to stop to allow the train travelling in the opposite direction to pass," Mr Anat said. "During peak hour, there can be a long line of trains waiting to pass that station, which makes the already busy line out of control."
BTS has already added extra carriages to its Silom line trains to deal with the high demand, but that strategy is already reaching its limits. All trains now have four carriages, each capable of carrying 300 people.
Mr Anat explained that all BTS stations are 150 metres long and are able to handle trains of up to six carriages — except Saphan Taksin, which can only handle a maximum of four carriages.
BTS designed the system to be able to move 50,000 people per hour in each direction, but that rule can't apply to the Silom line because of the constraints imposed by Saphan Taksin station, Mr Anat added.
On the Sukhumvit line, trains during peak times are running at 85-90% of maximum capacity. "If the train is completely full, there will be six people per square metre," Mr Anat said.
Meanwhile, Silom line trains are frequently topping 95% of capacity during peak hours, with no apparent solution.
"We really have no measure to deal with this problem until we can remove [Saphan Taksin] station," Mr Anat said.
Silom line commuters say they are often forced to wait on crowded platforms for several trains to pass.
"I have to wait until at least three trains pass me by before I can get on the train, which take at least 15 minutes," said Saowapa Kamnoi, a regular BTS user.
"Even though it is frustrating, it is still better than being in a car that doesn't move."
Mr Anat said BTS is ready to solve the problem as soon as the BMA gives the green light to do so. If the demolition goes ahead, the BMA has proposed building an automatic walkway linking the Saphan Taksin station site with Surasak station, about 1km away.