As a londoner i never quite understand the high cost. A tube train as a batteryless electric vehicle must be as close to zero maintenance as one can get. Making them self driving dead easy compared to say an uber taxi. Infrastructure, rails etc, very low maintenance as any third world citizen would tell you.
Not quite so low cost as might seem. It's not so much the daily costs, which are very low, but the high intermittent costs. The trains work very hard around 19 hours a day, for some 24 hours for two days of the week. There's a lot of wear and tear so plenty of inspections, brake pad and other part changes.
Every now and then a whole train is pulled out for refurbishment, new wheels, bearings and host of other components, new upholstery, floor panels, glass replacements, repainting.
Then there's the tunnels maintenance. They suffer huge buildups of toxic wastes from brake pad wear and other dust sources, so they have to be brushed and vacuumed regularly for the safety of passengers.
There's two other intermittent tunnel work types too. One is rail replacement as they wear, remember they have constant trains running on them only minutes apart, not like a surface line with the occasional train.
The other tunnel work has occurred a number of times is upgrading or renewing the signalling system as the network has become ever busier.
Of course all these three types of tunnel work have to done in a small 4 hour window in the early hours. That means hitting each with a large number of workers in co-ordinated teams, and they have to be very highly paid for working at that anti social time under pressure in horrible conditions.
You can see how step by step these have been becoming more and more expensive, but it gets worse.
Occasionally whole new trains have to be ordered and commissioned, and like e-cars they are very expensive to buy, made more so by having to be specially designed expressly for the London system.
And now the most expensive of all, tunnelling and building a new line. The last whole new line was the Victoria Line, opened in the 1970s, but there was another undergound tunnel built as a link elsewhere later. These cost vast amounts that take decades to amortise, Crosslink being a good example £15 billions and counting.
As for self driving trains, that was achieved over 47 years ago with the Victoria Line in which the line is controlled and trains effectively driven from a Central London control room in SW1. So why do they have drivers sitting in the cab? It's the fault of the public, they kicked up about the prospect of having no driver so ever since there's a been man in each train cab holding a "dead mans handle" for a minimum of £40,000 a year.
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