This trend is quite old if you think about other means of transportation like the train: - London Underground: 1863 - Paris Métro : 1900 But you're right abo

This trend is quite old if you think about other means of transportation like the train: - London Underground: 1863 - Paris Métro : 1900 But you're right about cars tunnels, the infamous Seattle project can also be mentioned http://en.wikipedia.org/wiki/Alaskan_Way_Viaduct_replacement_tunnel http://en.wikipedia.org/wiki/Alaskan_Way_Viaduct_replacement...