Why is the London Underground's "tubes" shaped the way there are?

Question

Its shaped like an arch but why? I've searched but no cigar. Does any one the answer?

Answer 1

It is the design that can withstand the most weight.

Answer 2

Hello,

The Arch like design of the London Tube or Subway system, may be the best architectural  mode suited for that kind of structure.

Just like the Arch like fashion, that most bridges are built with over long expanses of water or motorways.  It supports the weight evenly at both ends of the structure.

And I can only speculate that the Arch Like structure of The Tubes, contribute to the FREE Flowing of AIR throughout the Inner Confines of the tunnel.

BringBaka.

Answer 3

Well, the tubes are over 100 years old.  I could be wrong about this, but maybe the early tunnel boring machines could only make circular tunnels.  I dunno, it seems logical to me.

Answer 4

The first of London's underground train lines was built in 1863 and were of the 'cut-and-cover' method, where a large trench was cut into the ground from the surface the tunnel constructed from brick, using an arch-type shape for strength.  The remaining excavations were then filled in leaving the 'u'-shaped tunnel in place ready for the trains to run.

The older underground tunnels are smaller than the newer ones and need to have short height trains.

Answer 5

they probobly shape around the tubes if not for another good excuse and reason.

Answer 6

Most tunnels and many mines are made with arched or at least rounded roof as this is most stable from an engineering point of view.  Forces pressing down from rock overhead could push bits and pieces out of a flat roofed tunnel, but with a rounded or arched roof the forces are distributed to the sides where they flow down below the tunnel.  That is the crude and perhaps not quite correct explanation - I'm not an engineer.  If the roof was flat it would have to be held up all over the place by steel or by roof bolts at extra expense, and probably with less safety.

Nearly all things that have to withstand external or internal pressures are cylindrical  or even spherical.  Gas cylinders, aircraft, submarines, space shuttles, steam locomotive boilers and the list goes on.