Well, didn't all of these "inventions" happen in THE SAME generation?

Your definition of generation is 3-5 times longer than the usual definitions.

Addressing approximate timeframe of commercialization:

the train

1812. http://en.wikipedia.org/wiki/Salamanca_(locomotive)

the telegraph

1837, +25 years. http://en.wikipedia.org/wiki/Cooke_and_Wheatstone_telegraph

the telephone

Bell/Gray was 1876, commercialization by 1878. +40 years. http://en.wikipedia.org/wiki/History_of_the_telephone

the radio

Mid-to-late 1890s. 1895-1877=18 years. http://en.wikipedia.org/wiki/Invention_of_radio