UIC Railways
Introduction
The UIC Classification of Locomotive Axle Arrangements[1] describes the wheel arrangement of locomotives, multiple units and trams. It has been set out by the International Union of Railways (UIC) in Booklet 650 (Standard Designation of Locomotive Axle Arrangements and Multiple Unit Sets). It is used in much of the world. The United Kingdom uses a similar scheme. In the United States, the simplified AAR classification is used for modern locomotives.
It is a more versatile system than Whyte notation, being more precise in the design of locomotives. In the latter, some locomotives are impossible to classify, but the UIC classification handles them easily. Furthermore, the UIC classification is much more suitable for diesel and electric locomotives.
It is also known as German classification or Italian classification.
Structure
While Whyte notation counts wheels, UIC notation counts axles.
Garratt-type locomotives are indicated by parentheses or by placing "plus" signs between individual units.
The most used layouts on modern locomotives are the Bo′Bo′ and the Co′Co′.
Other systems
English system
Whyte notation was in common use in the United Kingdom. The Southern Railway&action=edit&redlink=1 "Southern Railway (Great Britain) (not yet drafted)") used a modified system of the UIC method. Oliver Bulleid, the Chief Mechanical Engineer, numbered his Pacific 21C XXX class 4-6-2 Battle of Britain"), referring to the guide wheels, tail wheels and finally drive wheels. The UIC classification for these machines is 2′C1′, Whyte 4-6-2.
French system
The French system resembles the Anglo-American system (Whyte), but counts axles instead of wheels and does not use dashes. Thus, a 2'D1' locomotive will be a "241" according to the French system. The SNCF has designated its locomotive series based on this system; e.g. the "221 A" or the "240 P". This system of counting the axles has also been used in Spain and Russia.
Turkish system
The Turkish system is probably the oldest used to classify locomotives. It consists of two one- or two-digit figures, in which the first indicates the number of driving axles and the second, the total number of axles. As in France, it is used in Türkiye to designate locomotive series. Returning to the example above, a "241" according to the French system and "4-8-2" according to Whyte's, will be a "47" according to Turkish. A Mallet (1'D)D1' locomotive, which would be a "14+41" according to the French system and a "2-8-8-2" according to Whyte's, will be an "810" (i.e. "45+45") according to the Turkish one.