MF 88

The MF 88 (Métro Fer appel d'offres de 1988; Steel-wheeled metro ordered in 1988) is a steel-wheel variant of electric multiple units used on Paris's Métro system. RATP contracted a consortium of manufacturers, with Ateliers du Nord de la France in charge of the project.

They were built following successful tests of a prototype train-set called the "BOA", derived from the MF 77, which tested new features such as open gangway connections between cars to improve passenger distribution and special bogies to reduce friction caused by the sharp curves found in the Métro network. The MF 88 introduced a number of innovations in its time, including AC induction motors and an on-board computer system using a new standard integrated computing architecture. It is planned for the MF 19 rolling stock to replace the MF 88 in 2025.

Design
Carrying on the features of the BOA, a total of nine MF 88 train-sets were built, which have only ever operated on Line 7bis in a three-car formation. It was the first model with AC motors, supplied by GEC Alsthom, as opposed to DC and with interconnecting gangways. The MF 88 was also the first to adopt a new computing architecture, developed by TechnicAtome, over relay-based systems used in older Paris Metro rolling stock. It also introduced an independent-wheeled steering axle design, but this turned out to cause several problems for RATP and was not adopted in subsequent Paris Metro rolling stock.

It was also the last model not newly built with automatic announcements and with user-activated doors (all subsequent models, as well as more recently the MF 77s on Line 13, have had all doors open at once). The high rate of wear-and-tear of the train-sets has made maintenance much more expensive than expected. The independent-wheeled steering axle design was found to be problematic and was causing excessive wear on the track. This is because of the design flaw in the chassis, each intermediate bogie only has one axle, similar to a typical car, bus, some rubber-tyred trains (although the rubber-tyred lines of the Paris Métro use the typical 2-axle bogies), or certain railbuses, but unusual for a more “standard” railcar, especially one powered by electricity.

Technical specifications

 * Manufacturers: GEC Alsthom, Faiveley, Renault, ANF
 * Electric source:
 * Traction: Gate turn-off thyristor (GTO)
 * Power: 2 motors per motor coach with 210 kW each, 840 kW total per train
 * Maximum operating speed: 70 km/h, currently reduced to 40 km/h due to rolling stock's condition
 * Bogies: Bi-directional
 * Length: 46.44 m



Formations
As of 1 September 2022, eight MF 88 trainsets were in service and were formed as shown below. One trainset was scrapped in 2013.

As of 1 March 2022, eight trainsets are allocated to Pré Saint-Gervais depot for use on Line 7bis.