France: SEREM - CODER freight wagon

Railway companies: SNCF - French National Railway Company


November 17th

After the UFR system for carrying trailers on railways wagons, the Company for Studies and Mechanical Achievements (Societe d'Etudes et de REalisations Mécaniques - SEREM) proposes a trailer whose body, after retraction of the rear wheel set, comes to rest directly on the floor of the wagon, thus resolving the wedging problem while increasing the trailer height.

SEREM, which filed its patent on November 17th, 1937, joined forces with the CODER establishments of Marseille-Saint-Marcel for the construction of the required material.

Sources: Les rails de l'histoire n° 4 -


June 20th

The French National Railway Company - SNCF decision to favour the UFR system triggers a controversy. Worried about the growing interest shown by the public authorities in rail transport, several road carriers groups are trying to slow down the movement and denounce the sidelining by the national company of the SEREM - CODER system.

The French National Railway Company - SNCF protests and assures that it has established its conviction on the technical superiority of UFR trailers based on long experience and numerous adaptations to increase their solidity, which their rivals, in operation only since 1938, cannot take advantage of.

A compromise is found and the French National Railway Company - SNCF agrees to acquire 50 trailers for the SEREM - CODER system which roughly corresponds to the proportion of road carriers interested in this system

The decision is confirmed by the ministerial authorisation on June 20th, 1941 for the order of 250x UFR trailers and 50x SEREM - CODER trailers.

Sources: Les rails de l'histoire n° 4 -


July 9th

The French National Railway Company - SNCF entrusts the Professional Organisation Committee for the Industry and Trade in Rail Transport Equipment with the task of finding the manufacturers for the new material.

In the case of the SEREM - CODER system, the best proposal comes from the CODER company and a contract is signed on July 9th, 1941, for 25x vans (with a payload of 8 t) and 25x tanks (with a capacity of 8.000 l and two equal compartments). The constructions is the responsibility of the CODER workshops located in Marseille in Saint-Marcel district.

The trailers ordered are primarily intended for road carriers who have agreed to abandon part of their long-distance services in favour of rail transport. During the war, thirteen companies signed agreements to this effect: in exchange for handing over a quota of goods to rail transport, they are guaranteed to receive a certain number of these new trailers (either the UFR system or the SEREM - CODER system to choose from) in full ownership (the financing is covered for about 30% by the road companies and for 70% by the French National Railway Company - SNCF) and the insurance of having the platforms and wagons necessary for their loading / unloading and their transport. Amendments are subsequently made to take into account possible obstacles to movement by rail and destruction of equipment attributable to acts of war.

Sources: Les rails de l'histoire n° 4 -


The shortage of materials delayed the execution of contracts and deliveries of the new trailers are phased between 1943 and 1946.

As of December 31st, 1945, only 4x SEREM - CODER-type trailers are in service.

But the French National Railway Company - SNCF anticipate an increase in demand after the war and even if the 1941 order is not completely delivered they do not hesitate to order 30x road trailers in the summer of 1945 and 25x carrier wagons in the winter if 1945.

Sources: Les rails de l'histoire n° 4 -


Despite the order is confirmed in 1946, it will never be delivered and the CEREM-CODER system will not be used anymore.

The definitive renunciation to the CEREM-CODER system is the result of the technical adjustments which had to be made to this equipment, as the French National Railway Company - SNCF feared in 1941. The announced advantage was not to require any specific development for the carrier wagons. However, in order to prevent the trailers from ripping during transport, the wagons had to be very quickly equipped with a sort of "cradle", the installation and removal of which required a lot of work. Coupled with the fragility of the trailers, in particular that of their wheel retraction system, this drawback became crippling for the French National Railway Company - SNCF , especially as the CODER establishments refused to undertake any improvement work.

Sources: Sources: Les rails de l'histoire n° 4 -

Latest update on the 15th of August 2021 at 19:40

Contributor(s): Tudor C.

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