Class 7800/DD-AR

Number series: 7801 - 7879
UIC Class: 94 84 4168 xxx-x
Number built: 50
Number in service: 50 (January 2009)
Introduced: 1997-1998
Axle arrangement: Bo'Bo'Bo'+2'2'+2'2'+2'2'
Continuous power rating: 6x400 = 2400kW
Maximum speed: 140km/h
Weight in working order: 218 tonnes
Length: 101.086m
Builder mechanical part mDDM: De Dietrich (France)
Builder electrical part mDDM: ADtranz and Holec
Builder coaches: Talbot (Germany)
Passenger seating: 80 first and 344 second class

In the beginning of the 1990s the Dutch Railways were in need of many new passenger seats. Mainly because of (almost) free travel of students and soldiers the number of passenger kilometers grew fast, and many trains were overcrowded. In the hurry it was chosen to use the design of the double deck coaches class DDM, and to couple these to new electric locomotives class 1700 (very similar to the existing class 1600). Later the locomotives would be replaced by motor cars, to allow the locomotives to replace older locomotives of class 1100, 1200 and 1300, that could then be scrapped.
In autumn 1996 the first double deck motor car class mDDM, with the number 390 7701, entered The Netherlands. It is of a rather uncommon design. Not regarding the outline (which is similar to the existing driving trailers) but because the motor car has three 2-axle bogies, electric equipment on the lower floor and passenger seating on the top floor! It was chosen to use 3 bogies with 2 powered axles each because limited space only allowed the installation of relatively small motors. To get enough power 6 axles were needed, and 3 Bo' bogies were preferred over 2 Co' bogies. The middle bogie is allowed to shift 15 cm to both sides in curves.
Because passenger seating is located on top of the electrical equipment, special care was taken of the noise insulation of the floor. It is stated that the interior of the motor car is even less noisy than the coaches. The passenger floor is located a little bit less high than the top floor in the coaches, such that the "bending windows" used on the top floor of the coaches could be replaced by flat windows.
Because only 50 motor cars will be delivered not all locomotives can be replaced by them. The motor cars will be coupled to the sets of 3 double deck coaches, while the 4-car sets will stay coupled to locomotives. The first set class 7800, consisting of a motor car and 3 coaches, entered passenger service in July 1997 on the line Lelystad-Amsterdam-Enkhuizen. On the 1st of October that year series delivery started with motor car 390 7704, and on the 22nd of October large-scale training for drivers started. At the end of 1998 all new motor cars were delivered, and all are now in use. In exploitation no difference is made between loco+4 coaches and mDDM+3 coaches, although the first has much more second class and less first class seats than the latter!
The sets of motor car and 3 coaches are considered to be trainsets, splitting up only takes place in the workshop. Two of such trainsets can be coupled, the can also be coupled to a set of 4 coaches + locomotive class 1700.