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Railway electrification

technology Maturity 5-7 Next article →

Railway electrification is the process of using electric power to drive rail transport. Instead of relying on onboard fuel, these systems use electricity to power motors for propulsion. This can be achieved using electric locomotives that pull separate cars or electric multiple units, which are passenger cars with their own integrated motors.

Europe rail electrification en
Europe rail electrification en

Most electric railways do not generate their own power. Instead, they purchase electricity from a utility company or a large generating station. This power is transmitted through a network to the railway. Once at the tracks, the railway provides its own distribution lines, switches, and transformers to deliver electricity to the trains.

To move a train, electricity must be transferred from the power lines to the vehicle while it is in motion. There are two primary methods for this contact. The first is the overhead line system, often called a catenary. In this setup, wires are suspended from poles, towers, or tunnel ceilings. A device on top of the train called a pantograph touches these wires to collect power.

4,03 Hauts de St-Aubin Citadis n°1016 (tram Angers) par Cramos
4,03 Hauts de St-Aubin Citadis n°1016 (tram Angers) par Cramos

The second method is the third rail system. This involves a rail mounted at track level that is contacted by a sliding pickup shoe on the train.

A metro station in Bucharest, showing it uses a 'third rail'
A metro station in Bucharest, showing it uses a 'third rail'

Most systems use the standard running rails to act as a return conductor for the electricity.

Electrification systems are classified by three main technical parameters: voltage, current, and frequency. The current can be direct current (DC) or alternating current (AC). Early railways relied on DC, but this type of current is limited because it cannot be transmitted efficiently over long distances. The development of AC in the early 20th century changed everything. AC allows for much more efficient power transmission over many miles.

Onderdel spoorwegnet
Onderdel spoorwegnet

Different regions use different combinations of these parameters. For example, many high-speed lines in France, Spain, and Italy operate using 25kV AC at a 50Hz frequency. Other regions might use 3kV DC or 1,500V DC depending on their specific infrastructure and needs.

The history of this technology began in the late 19th century with urban tramways. In 1881, the Gross-Lichterfelde Tramway in Berlin, Germany, became the first permanent electrified railway in the world. Shortly after, between 1887 and 1888, Frank Sprague successfully applied overhead line electrification in Richmond, Virginia. This success led to hundreds of street railways adopting the technology by the early 1890s. The first major mainline electrification occurred in the United States with the Baltimore and Ohio Railroad's Baltimore Belt Line in 1895–96. Throughout the 1920s and 1930s, countries like Sweden, France, and Italy began adopting these systems on a much larger scale.

There are significant advantages to choosing electricity over diesel engines. Electric trains are generally more powerful, more responsive, and more reliable. They are also much quieter, which is helpful in populated areas. Because they do not burn petroleum, they produce no local emissions, making them ideal for tunnels and cities.

LGV Cruzilles Mépillat 10
LGV Cruzilles Mépillat 10

Some advanced systems even use regenerative braking. This process captures the kinetic energy of a slowing train and turns it back into electricity. This energy is then returned to the supply system to be used by other trains or the general utility grid.

Despite these benefits, electrification presents certain challenges and costs. Building the necessary wires and substations requires very high capital costs. This can make electrification uneconomic for routes that do not have much passenger or freight traffic. Additionally, electric trains lack the flexibility of diesel trains because they are tied to the location of the wires. They are also vulnerable to power interruptions. To help solve this, some engineers use electro-diesel locomotives. These can run on diesel power if the electricity goes out or if the train reaches a section of track without wires.

As of 2022, electrified tracks account for nearly one-third of all railway tracks globally. Electrification continues to grow as countries look for sustainable transportation. While there were once concerns that overhead wires would interfere with double-stack cargo trains, this is no longer a universal problem. Both China Railway and Indian Railways now regularly operate electric double-stack cargo trains under overhead lines. This progress shows how electricity has become a fundamental part of modern global infrastructure.

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🖼️ Images & Media (12)
File:Europe rail electrification en.svg
Europe rail electrification en.svg
File:LGV Cruzilles Mépillat 10.jpg
LGV Cruzilles Mépillat 10.jpg
File:4,03 Hauts de St-Aubin Citadis n°1016 (tram Angers) par Cramos.JPG
4,03 Hauts de St-Aubin Citadis n°1016...
File:A metro station in Bucharest, showing it uses a 'third rail'.jpg
A metro station in Bucharest, showing it...
File:EalingCommon3.jpg
EalingCommon3.jpg
File:Bogie-metro-Meteor-p1010692.jpg
Bogie-metro-Meteor-p1010692.jpg
File:ÖBB Vectron 1293 015 - Bhf Rattenberg - Tirol - AT.jpg
ÖBB Vectron 1293 015 - Bhf Rattenberg -...
File:Onderdel spoorwegnet.gif
Onderdel spoorwegnet.gif
File:2012-11-03 BDhe48 218-211 04 Eigergletscher.jpg
2012-11-03 BDhe48 218-211 04 Eigergletscher.jpg
File:Thomas Robert Way00.jpg
Thomas Robert Way00.jpg
File:Berwick-upon-Tweed MMB 14 Royal Border Bridge.jpg
Berwick-upon-Tweed MMB 14 Royal Border Bridge.jpg
File:DTTX 724681 20050529 IL Rochelle.jpg
DTTX 724681 20050529 IL Rochelle.jpg
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