The Railway Jargon...demystified...

One small comment that appeared for the post "Yet another railfanning at Bangalore City!" is the nucleus on this post. The comment said:
Never saw someone deal with those letters like WDGPOIM etc with such felicity... great! But could you also explain in our posts what these letters mean... Your blog has a great potential to demystify Railways for the millions of common people.
Here I go! The locos on the Indian Railway system are mainly of two types: the Electrics and the Diesels! (I call the former as a Female and the latter as a male - I wouldn't go into the details, else I'd end up stirring a hornets' nest!). India has a variety of gauges for this railway system namely: Broad (1676mm - the most common Gauge in India - a majority of the routes in India are on this Gauge), Metre (1000mm - the erstwhile standard on many routes in India. Being converted to Broad as a part of Project Unigauge) and Narrow (762mm & 610mm).

I'd keep my discussions limited mainly to Broad Gauge locos only - that too only the most commonly seen ones! I am a diesel fan in all ways. The reason behind the love for diesels is obviously the sounds and smoke from a diesel locos - somethings absent entirely on an electric loco!

Locos in India are broadly divided based on their intended use into: Mixed, Passenger and Freight (Goods). All locos are given a "class" name, which basically consists of Alphanumeric characters. Three Alphabets followed by a Number denote the class name. Another alphabet may be added after the Number to denote "sub-classes".

The meaning of these alphabets are: The first one stands for the Gauge of the loco:
W = Broad Gauge
Y = Metre Gauge
N = Narrow Gauge (610mm)
Z = Narrow Gauge (762mm)

The second character stands for the power source:
D = Diesel
A = AC Electric
C = DC Electric
CA = AC/DC Electric (runs on both)

The third character stands for the intended purpose:
M = Mixed (works Passenger & Freight)
P = Passenger
G = Freight (Goods)
S = Shunting

The number denotes the "series" of the loco (incase of Electrics and Branch line Diesels), while this number denoted the power (in HP) of the loco (for main line Broad gauge Diesel locos). Number "1" would denote a thousand hp.

The alphabet suffix after the number would denote the sub-class of the loco. In diesel locos it also means an increase of a 100hp over the power denoted by the number i.e., 3A would mean 3100hp, while 3C would mean 3300hp!

So, the syntax of writing a loco's class name would be: [Gauge][Power][Purpose][Series][Sub-class]

Now, WDG3A follows this syntax, and the expansion for this class would be: Broad Guage Diesel Freight (Goods) 3100hp locomotive!

There are some exceptions to this nomenclature though! A WDM2 is a 2600hp loco, while WDM2A too is a 2600hp loco but works only on Air-Brake! Similarly, WDM2B is also a 2600hp loco but with dual brakes (Air & Vacuum) brakes working! WDP1 is a 2300hp loco, while the WDM7 is a 2000hp locos! These locos have odd classes because they are exempted from following the mainline BG Diesel classification system since these locos are intended to operate on branch lines!

In case of an Electric Locomotive, the number denotes the series in which the loco was actually produced (or designed). This a WAP4 would mean: Broad Gauge AC Electric Passenger 4th series loco i.e., it is the 4th loco in the "WAP" series to be produced!

The locomotives currently in Use in India are (only Broad Gauge):
Diesel: WDM2/2A/2B, WDM3A, WDM3C, WDM3D, WDP1, WDP3A, WDP4, WDG3A, WDG4
AC Electric: WAM4, WAP1, WAP4, WAP5, WAP7, WAG5, WAG6, WAG7, WAG9
DC Electric: WCG2, WCM6 (Only two were produced - One damaged in fire, and the other converted to AC traction!)
AC/DC Electric: WCAM1, WCAM2/2P, WCAM3, WCAG1
Diesel Shunters: WDS4B, WDS6/6B

Out of these, DC Electrics, and AC/DC Electrics are sort of exclusive to the Mumbai region, and they rarely venture out. AC/DC Electrics go upto a maximum of Ahmedabad on the WR line, and Manmad/Pune on the CR line. DC electrics are exclusively seen on Central Railway and work only to Pune side. The sole surviving DC electric is the WCG2 - which is all set to move to the scrapyard in less than a year from now. (A separate tribute post about the WCG2s would be put up later).

This is all about locos! A brief description about these locos would be put up later. I hope this post would demystify the railway jargon a bit. My next posts would demystify more of those terms.


Pradeep Nair said…
Binai, Thanks a lot for making those letters more understandable for ordinary people like me, who have always seen them, but never understood what they are.