Should we split this discussion, do you think? It may be better not to hijack the discussion about Swedish signals. I will defer to you on this, but reply in the meantime in the expectation that this may well be split from the Swedish signals thread.
I will number the replies to the feature suggestions.
1. Protecting roads: This may well be quite straightforward to implement. It would make sense, would it not, for private roads also to be able to have this designation (which could be set by the player(s) owning the roads), too, as player companies often want to be able to do this?
2. Zoning: This is definitely more complex. I think that one would have to be very clear about exactly what one is simulating with this feature: actual zoning would occur in cities with modern planning laws which would forbid construction except in zones, whereas in older times, no such restrictions existed. There would have to be a way of simulating which cities had these restrictions and which do not, perhaps by a toggle for each city. One would then have to think about how that would fit in with player buildings: ought players be able to put, e.g., a railway station in a residential area? An airport? The complexities of deciding how edge cases work would potentially be very great in this situation. Also, this would not be very useful on very large multi-player games, where it would be too difficult to maintain, and in which organic growth is more useful. For those reasons, this is not something that I am likely to add to Experimental in the near future, but I will not entirely rule it out, as it is difficult to predict where future development might take one, and there is also, of course, the prospect, albeit theoretical, of other developers taking an interest in working on this feature.
3. Electricity: Even in the current versions of Experimental, and a number of previous versions, being connected to electricity affects city growth after electricity starts to become important, and electricity can be supplied to cities more or less in the way that you suggest. This effect on growth is similar to the way in which goods, mail and passenger transport affects growth, and is actually based on code left over from Standard where it was evidently planned to do the same thing and the plan abandoned as no mechanism for supplying cities with electricity was ever implemented there. I plan in any event, when I get to rewriting city growth, to make the effect on growth where electricity is not present in modern times much more significant.