Trucks are large: they need bigger more expensive tunnels. It isn't that we cannot do it, it is just that tunnels are expensive, and the larger you make them the more expensive they become. While a car/truck less city sounds like a great idea, it isn't practical. There are a lot of goods that need to move around somehow for a city to work. While trains or horses could be used instead, both have issues as we get to the "last mile".

Thus I'm proposing get humans off the ground level - we have the technology to make this convenient today. The cost is not very high and it solves a lot of congestion problems on the street.