This is a bit of a modernization of a perennial HN favorite: the Chicago Tunnel Company. http://en.wikipedia.org/wiki/Chicago_Tunnel_Company http://en.wikipedi

This is a bit of a modernization of a perennial HN favorite: the Chicago Tunnel Company. http://en.wikipedia.org/wiki/Chicago_Tunnel_Company http://en.wikipedia.org/wiki/Chicago_Tunnel_Company For years, a network of tunnels connected downtown Chicago buildings with a narrow gauge freight railway. It also doubled as an air conditioning duct for some buildings. Depending on who you ask, it either failed because of politics (regulation of passenger traffic, etc.) or economics (deliveries from outside the network dominated later office traffic, which had to be carried by trucks), change (the switch to natural gas instead of coal siphoned off a lot of traffic), or geography (floods).