That's the primary conceit of Urban Mole, a conceptual project by designer Phillip Hermes. He suggests using the existing sewer infrastructure to transport all manner of packages via robotic messenger-a series of tubes, if you will (reminds me of pneu-mail). The sudden lack of street-clogging delivery trucks could have a profound effect on congestion, both in terms of traffic and air quality. You can see a similar project called UNITX, including an actual prototype, here.If you could build a city from scratch, incorporating the past hundred-plus years of urban planning knowledge, chances are you would end up with metropolises that look much different than the big cities we currently have. But because that's impossible, proposals that seek to repurpose existing infrastructure in service of modern needs are always worthy of consideration.Via Wired.