NMBS/SNCB Classical twin EMUs (also referred by their construction year - AM50 for "Automotrice 1950" up to AM79 for the last units from 1979) are electric multiple unit trains operated by the National Railway Company of Belgium (NMBS/SNCB). They are the standard train for internal workings under the Belgian standard 3000 Volts DC overhead lines.
Classical EMUs were originally painted in dark green, with small yellow stripes surrounding the front lights. As those were considered insufficiently visible, the front door was also painted in yellow and the stripes were enlarged.
A subset of 22 EMUs was built with stainless steel body instead of (regular) carbon steel. This remains a one shot trial as the next generations were equipped with carbon steel bodies.
Another subset of 6 EMUs were specifically adapted for airport service, with more space between seats and a huge luggage compartment. Although they were operated by SNCB staff, access was restricted to Belgian airlines travellers with a dedicated platform at Brussels Central Station. A blue painting scheme was also chosen to identify those EMUs.
In 1984, SNCB introduced a new transportation plan based on fixed-interval timetables (and the closure of most secondary passenger lines) called "Plan IC-IR." A new paint scheme was applied, based on a burgundy red color with a large white line surrounding the entire coaches or EMUs below the windows.
In 1999, classical EMUs built in the seventies were involved in a refurbishing program which included comfort upgrade (interior replacement, sound system, closed circuit toilets) and repainting in the light gray livery with blue and red lines under the windows. Few units were still in the older green delivery when refurbished. The last 40 to be refurbished units received extra features (LED information displays, multi-service compartments for bicycles or standing passengers) for suburban "CityRail" service.
In 2013, a hundred non-refurbished units were scrapped, after many of the Desiro Mainline Class AM 08 entered into revenue service.