Astra IVA is a family of metro train used by Bucharest Metro, of which 504 cars (252 two-car sets) were built between 1976 and 1993 by ASTRA Vagoane S.A. in Arad, Romania.
The trains used on the system are made up of various trainsets (rame) connected together. Each trainset is made up of two permanently connected train-cars (B'B'-B'B' formation) that can only be run together. Normally, 3 two-car sets are coupled together to make a complete six-car formation.
Between 1994 and 1996, 42 cars (21 two-car sets) were refurbished by FAUR and Electroputere for service on Line M3, however for unknown reasons the refurbishment project was abandoned and these trainsets are currently stored at Berceni Depot. These trains were distinguished by a blue livery, and featured new technical equipment. An attempt to build more intermediate coaches to allow for a 3-car x 2 formation was abandoned in 1995. In 2000, most of the Astra IVA coaches were refurbished and equipped with new ATO and ATP signalling systems, allowing for partial driverless operation especially on Line M4.
The Astra Arad rolling stock is approaching the end of its service life, so the cars are being gradually phased out in favour of newer Bombardier Movia and CAF trains. As of January 2017, 15 trainsets (90 modular cars) are in commercial service.
Source: metroubucuresti.webs.com