What do the numbers on the Indian Railway locomotives convey?

Train journeys are thrilling, especially for the occasional train traveller. The excitement starts with the preparation for the train journey and continues as one waits for the train on the platform, watches the massive locomotive hauling a long chain of coaches and coming to a halt, then being seated in the train, and watching the fellow passengers representing mini India and having conversations with them, and as the train moves… admiring the ever-changing landscape and rail stations on either side, having snacks and meals and sleeping in the train, and this train-excitement would only end when the destination is reached.

If one is not in a train, just watching a train passing by catches our attention and one stops to admire this marvellous travel and transport mode. Whether it is a passenger train or a goods train it does not matter and especially the locomotives of different models and sizes are certainly an eye-catcher. In all such encounters what one misses is the knowledge of the numbers prominently marked in front of the locomotives. And this article is to explain all about these numbers… the tell-all classification of the locomotives.

The Indian Railways primarily operates a fleet of electric and diesel locomotives. Steam locomotives have become obsolete and are now operated on a few World Heritage sites and also run occasionally as heritage trains. In our country, a locomotive is also known as a loco and more popularly as an engine.

Locomotives are classified by track gauge, motive power, function and power in a four or five-letter code (model number). The first letter denotes the track gauge. The second letter denotes motive power (diesel or electric), and the third letter denotes use (goods, passenger, mixed or shunting).

CLASSIFICATION:

FIRST LETTER (gauge):

W – Broad gauge (wide) – 5 ft 6 in (1,676 mm)

Y – Metre gauge (yard) – 1,000 mm (3 ft 3+3⁄8 in)

Z – 2 ft 6 in (762 mm) narrow gauge

N – 2 ft (610 mm) narrow (toy) gauge

SECOND LETTER (motive power):

D – Diesel

C – DC electric (DC overhead line)

A – AC electric (AC overhead line)

CA – DC and AC (AC or DC overhead line); CA is considered one letter

B – Battery (rare)

THIRD LETTER (job type):

G – Goods

P – Passenger

M – Mixed (goods and passenger)

S – Shunting (switching)

U – Multiple units (electric or diesel)

R – Railcar

The fourth item, 'series', is a digit identifying the model of the loco. Until recently, this series number was simply assigned chronologically as new models of locos were introduced. However, starting in 2002, for diesel passenger, goods, and mixed locos, i.e., WDP, WDG, and WDM sequences, (and only for them, apparently, not for electrics, and diesel shunters), the series digit identifies the horsepower range of the loco, with '3' for locos with over 3000hp but less than 4000hp, '5' for locos over 5000hp but less than 6000hp, etc. This new scheme is applied to all passenger/goods/mixed-haul diesel locos starting from June 2002, except for the WDM-2 and WDP-1 classes of locos.

In the above pictures, you see a WDM 2A engine and a YDM 4 engine. In the engine marked WDM 2A, W - denotes broad gauge; D - denotes diesel power; M - denotes mixed-use (goods and passenger service), and 2A denotes over 2000 hp (1500 kW). And YDM 4 engine means, Y - Metre gauge, D – Diesel, M – Mixed (goods and passenger) and 4 – Series number.

This system does not apply to steam locomotives, which are no longer used on main lines. They retain their original class names, such as M- or WP-class.

Very common Broad-gauge electric classification codes are:

WAM – Wide AC electric mixed

WAP – Wide AC electric passenger

WAG – Wide AC electric goods

WCM – Wide DC electric mixed

WCP – Wide DC electric passenger

WCG – Wide DC electric goods

WCAM – Wide AC/DC electric mixed

WCAG – Wide AC/DC electric goods

In the fiscal year ending March 2020, IR carried 808.6 crore (8.086 billion) passengers and transported 121.22 crore (1.2122 billion) tonnes of freight.

IR runs 13,169 passenger trains daily, on both long-distance and suburban routes, covering 7,325 stations across India. Mail or Express trains, the most common types of trains, run at an average speed of 50.6 km/h (31.4 mph). Suburban EMUs run at an average speed of 37.5 km/h (23.3 mph). Ordinary passenger trains (incl. mixed) run at an average speed of 33.5 km/h (20.8 mph). The maximum speed of passenger trains varies, with a few Express trains running at a peak speed of 160 km/h (99 mph).

In the freight segment, IR runs 8,479 trains daily. The average speed of freight trains is around 24 km/h (15 mph). The maximum speed of freight trains varies from 60–75 km/h (37–47 mph) depending on their axle load with 'container special' trains running at a peak speed of 100 km/h (62 mph).

As of March 2020, Indian Railways' rolling stock consisted of 2,93,077 freight wagons, 76,608 passenger coaches and 12,729 locomotives. IR owns locomotive and coach-production facilities at several locations in India. It had 1.254 million (12.54 lakh) employees as of March 2020, making it the world's eighth-largest employer. The government has committed to electrifying India's entire rail network by 2023–24, and become a "net-zero (carbon emissions) railway" by 2030.

Topmost powerful Locomotives of Indian Railways:

WAG-9 (Wide, AC, Goods):

Total WAG-9 Locomotives Active as of 01-06-2021: 2305

Indian Locomotive Class WAG-9 is currently the second most powerful and popular freight locomotive used by Indian Railways. WAG-9H class is mostly used as a freight locomotive and is the second heaviest locomotive.

Two WAG-9 class units can haul a load of 4,500 tonnes on grades of 1 in 60 (1.67%), that is 58 Box wagons. The locomotive can run even in 100% humidity, or in deserts, where there is a high saturation of conductive particles. The maximum speed of this locomotive is 120 km/h (75 mph) and power output of WAG-9 is 6,122 hp (4,565 KW) and of WAG-9HH is 9,000 hp (6,122 kW).

Indian Locomotive Class WAP-7 (Wide, AC, Passenger):

The Indian locomotive class WAP-7 is a class of 25 kV AC electric locomotives that was developed in 1999 by Chittaranjan Locomotive Works (CLW) for Indian Railways. The model name stands for broad gauge (W), AC Current (A), Passenger traffic (P) engine, 7th generation. They entered service in 2000. A total of 1366 WAP-7 have been built so far, and more units are being built at CLW, Banaras Locomotive Works (BLW) and Diesel-Loco Modernisation Works (DLMW).

Total Locomotives Active as of 01-06-2021: 1366

The WAP-7 is one of the most successful locomotives of Indian Railways serving passenger trains for over 20 years. WAP-7 is capable of hauling 24 coach trains at speeds 110–140 km/h (68–87 mph). However, the locomotive Maximum speed is 180 km/h (110 mph) and the Power output is 6,122 hp (4,565 kW).

Indian locomotive class WAG-12 (Wide, AC, Goods):

The Indian locomotive class WAG-12B is a class of 25 kV AC electric locomotives that was developed in 2017 by Alstom for the Indian Railways. The model name stands for broad gauge (W), Alternating Current (AC), Goods traffic (G) locomotive, 12th generation. They entered trial service in 2019. A total of 800 WAG-12B are to be built at Electric Locomotive Factory, Madhepura, in Bihar by 2028.

Total Locomotives Active as of June 2021:110

With a power output of 12,000 HP, they are twice as powerful as their immediate predecessor, WAG-9, and it is one of the most powerful freight locomotives in the world. It will be used to haul freight trains weighing more than 6,000 tonnes at speeds of 100 km/h (62 mph) to 120 km/h (75 mph), essentially doubling the average speed of freight trains in the sector.