Infinitesimally beared tube mail
From apm
In an upgraded street infrastructure some kind of advanced tube mail could be integrated to transport stuff that is not a produtc of advanced productive nanosystems like food, wool, paper, wood, plastic parts, metal parts, glass parts and many more.
Such a design could be imagined as cylindrical capsules (some 10cm in size) in vacuum pipes with capsule propelleing shearing drive walls. If the vacuum tube walls are designed as an inflatable structure the system can have very low mass (saving cost). Vibrations may be an issue then though.
