DHL delivery vehicles
Underground mailbox and delivery vehicles

Underground Mailbox is a delivery system consisting of a vehicle and a sub-terrestrial mailbox. The vehicle comes with three wheels: The front one is powered by pedals, and the other two are powered by an electric motor. Instead of boxes, it comes with luggage trolleys at the back. The driver arrives at one of the special underground district mailboxes where a mechanical arm brings him the boxes to be sent. The driver collects them, leaving those with addressees in this particular district. The box's addressee can fetch his box whenever he likes by using a remote control to activate his mailbox. The latter rises from the ground using the same principle as mobile road-blocks.