The BTS Skytrain will upgrade new software for its signalling system tonight and make a test run over the coming long weekend that could cause some delays of up to 20 minutes, according to Bangkok Mass Transit System Plc (BTSC), the Skytrain operator.
CEO Surapong Laoha-unya described the potential delays as a "worst-case scenario", adding the probability of them occurring was "less than 1%".
He said it would take just 10 minutes to set up the new system, necessitating a 10-minute cessation of services.
"Since the malfunctions that occurred on the Skytrain system from June 25-29, we have fixed and improved the system and [changed] the radio channels that require the software upgrade," he said.
After conducting a series of tests, the BTSC will issue the upgrade and execute a dry run outside normal operating hours between 1am and 4.30am on July 27, it said.
The BTSC has opted for a rail control system produced by Bombardier Transportation, a Canadian manufacturer, that will upgrade an entire line on the Skytrain system.
Gregory Enjalbert, a vice-president at Bombardier, said the upgrade would also support future lines including two planned extensions. One of these is due to start operating between Samrong Station and Keha Samut Prakan Station from December.
"There are two ways to upgrade the rail system software. One was is to close all the systems, which would take one or two weeks and is quite tricky in such a big city," he said.
The other is to do it at night after the rail operation closes, he said, adding the company would finish improving the system by December at the latest.
"We'll spend the long weekend upgrading the system. If there are any delays or hiccups caused by the change from an automatic to manual system, it will be [done] for passengers' safety," Mr Enjalbert said.
Overlapping frequencies caused the malfunctions late last month. Pundits said this is rare as the 2.4GHz bandwidth is a widely used standard.
"In more than 60 countries where we've installed the rail control system, we've never experienced such a problem," Mr Enjalbert added.
