Bangkok Elevated Road and Train System. 25kV traction voltage for a mass transit railway

The Bangkok Elevated Road and Train System (BERTS) is a turnkey project to elevate the existing State Railway main line and to provide a community train (CT) for mass transit with an elevated three-lane highway above the trains. Phase I of the project consists of a route length of 45 km within Bangkok Metropolis. The railway medium voltage electrical system comprises 25 kV single-phase traction and 22 kV substation supplies, which are derived from the 230 kV primary network of the electricity supply authority via three bulk supply substations adjacent to the route of the railway. Supplies for the main line stations and the highway etc. are derived from the CT station substations. Initial CT operation consists of 4 car trains at 3 minute headways, with a maximum capacity of 9 car trains at 2 minute headways. 230 kV was chosen as the standard nominal three-phase voltage available in Thailand on the basis of availability and economics