Because of the assumption of totally new city construction there may be an alternate, feasible solution.
Each property/building requires a unique address with connection to communications, electrical power, potable water supply and storm water pipes. Optionally there may be a recycled water supply for gardens, toilets, etc. Plus organic waste, recycling waste and hard waste services. All of these require trenching for underground pipes and conduit. if this trenching work is done prior to building construction or as part of foundation work then the cost of increasing the diameter of services for package delivery is trivial. A previous answer suggested laying pipes, conduits, etc. on ground level and raising the buildings by one level. A variant would be to lay the pipes, etc. on ground level and back fill over the pipes and conduits to establish a new ground level. With the use of suitable back fill material you could aim for well drained soil.
With a suitable design with recycling pumps the potable water supply can have continuous flow. Increase the diameter of the water pipes and the system could be used to delivery water proof cargo capsules. As each location has a unique address then RFID or equivalent technology could be used for package routing and delivery. It should be possible to have a hierarchy of pipe sizes for packages. For additional cost a property/building owner could specify a larger diameter pipe. To reduce pipe pressure each property would require a pump to raise water pressure. 87
Pump input could automatically swap between local storm water tanks and the low pressure, mains water supply. Return of used carriers could be using a continuous flow storm water system. In the event of a storm event the return carriers would be flushed from the system to increase storm water capacity. Without capsules the storm water system would be able to handle the increased water flows. Only sterilized capsules could have access to the delivery system (potable water supply). Every property would be restricted to the storm water system. At the storm water system pumping stations the there would be sorting of the full from the empty, return capsules. Sterilized capsules would be inserted into the delivery system. If required, empty capsules could be then be delivered to properties for reuse. There could be different capsules for different contents. With RFID technology high priority capsules could be given processing priority. Each property would be required to extract capsules from the system. so there can not be a backlog causing a jam. If there was a jam deliveries to the affected address would be held back. Aim would be automate the system. Using fluid logic as an alternative to RFID it should be possible to use the water flow to route packages. 284