The kind of intact Kingsway tram tunnel can still be seen in London. It was much celebrated by The Goons with their comedy radio piece, The Last London Tram. I have it as MP3 file. Can't recall where I found it but I am sure it is not hard.
The essence of the story was that two and a half years after London's tram system was closed down and the office was being wound up, a pin was discovered on a board indicating there was a tram still in the Kingsway tunnel around two years after the tram system closed. Sure enough, there was, complete with driver and conductor. They also had a passenger who refused to disembark because he had paid his fare to a place but the tram was to run to the depot as the last London tram. The driver and conductor refused to move the tram without a guarantee of a ceremony. Very amusing.
I am not sure about all of London's trams, but certainly the tram that ran through the tunnel was powered via a conduit between the rails and not by overhead wiring.
The tunnel ran from Southampton Row near Holborn Station along the length of Kingsway to emerge under Waterloo Bridge on the north bank of the Thames River. Some of the tunnel has been used for a motor car tunnel, but much is still intact.
What a marvellous thing to still be in situ in London, but London was not alone with having trams running in tunnels. Sydney trams after crossing the Harbour Bridge ran in tunnels to terminate at Wynyard Station. The Sydney tunnels are still there. One is used for carparking. I surprise myself. I have written about the Sydney tram tunnels before.
You can read of an exploration of the Kingsway tunnel here.
I believe this tram is descending into the Kingsway tunnel. How can you tell? Originally single deck trams ran in the tunnel but later curves on the roof were removed to allow double deck trams to use the tunnel.
It is locked off now, but this is the tunnel entrance
You can see it here with Google's Street View.
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