Why does a railway track have a particular shape I ?

As you can see, the I shape of the track supports the train wheels efficiently. The train wheel shape is made in such a way that the I shape of the track will help it remain on track and guide it efficiently on a curved track

The railway track has the shape of I because the top part or upper half should be wide enough to support the fast moving wheels and flat bottom or lower half should be wide & thick enough for clamping.

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