How I'd do zoning: Nuisance

As time goes by, I like the idea of zoning less and less. It's a useful tool for planners, but it's really only useful for generating suburban sprawl. Rather, it's useful for real-estate speculation, as it ensure that the context around the new development is less likely to suddenly change: No pork rendering facility will suddenly occur next to the planned ranchettes. (This is largely a problem of suburbia, because only in the context of highway-enabled sprawl do land values change suddenly and systematically). 

So: How I propose to do zoning: Nuisance-based. Say, for example, there are three dimensions of nuisance: noise, shade and traffic. A 'noise' zone gets labeled by the maximum (peak) noise that can be generated at property edge: Airports would be in a 150 decibel zone, industrial in a 120 decibel zone, and cottage residential a 60 decibel zone. Some of the zones would be established by roadway proximity: An arterial highway generates 80 decibels.  Seems too difficult to map? Someone already did.

Shadow-zoning is also simply to explain: Nothing built on a lot can cast shadow on an adjacent lot. (Shadow on public ROW is ok). For urban locations, the rule could be 'no shadow on the lot behind you'. 

'Traffic' means traffic generation: How much traffic your expect to generate. That's easy to measure: Count the parking stalls. Uses with similar numbers of parking stalls are compatible. If the house next door can park two cars on the lot, a commercial building with two parking stalls is also acceptable. A 7-11 with four stalls in the parking lot would be a legal use, while a CVS with 20 would not be. Size of lot would be irrelevant--this is not a 'per 1000 SF' measure.  (Elsewise, Target would just buy up a big lot and generate huge amounts of traffic). 

Form-based zoning beats the pants off Euclidian (use-based) zoning, but it's mostly useful for infilling single-family neighborhoods. Mixed-use areas are going to need something better.