The Electric Tube
Where the first electric tube lines began
The first deep line tubes in London opened in 1890 as electric lines. This was 27 years after the first tube line in the world opened in January 1867 which hauled people by steam power in gas lit carriages between Paddington and Farringdon.
After years of conflicting health reports, many lines were electrified at the start of the 20thcentury. It was in 1905 that the District and Circle lines were electrified, 37 years after they opened. However parts of the Metropolitan line were using steam trains until 1961!
Electric locomotion was in its infancy at the beginning of the tube and many decisions needed to be made as entrepreneurs invested significant money in creating these new lines. Choosing between AC and DC being one. A DC system has operated on the tube since the beginning and potential differences were provided via additional positively and negatively charged rails within and outside the wheel rails. Voltages began at 500V difference and now are standardised at -210V and +420V giving a 630V difference.
Over the years technology has improved and my two favourite titbits are that many of the stations (all on the Victoria line) sit at a slight hill which helps slow carriages when a train enters a station and helps accelerate the train when leaving. Also, modern trains use regenerative braking to recuperate energy.
Present and future investments
Today the Tube and Overground uses 1.2 TWh of electricity at a cost of over £130m per year. There is an ambitious plan to make the tube carbon neutral by 2050 and plans are afoot to build solar along outdoor sections of tube lines, battery storage at key points on the grid and purchasing volumes direct from nearby wind farms.