Roads can be made of various materials, and the choice depends mostly on: expected volume and vehicle types, and climate. For instance, dirt is OK for rural residential - but not rural commercial - because of the greater proportion of heavy vehicles. Likewise, dirt would not be appropriate in an urban setting due to sheer volume. As for climate, in general, the less flexible the pavement, the more susceptible it is to damage from water infiltration and frost heaving. You can build roads with concrete in a dry climate, and it may be more cost effective.
You could develop a 'condition index' based on several factors acting over time, and then when the player clicks on the road segment, the game might tell them something like "this road is wearing prematurely due to excessive heavy vehicle traffic, consider changing the surface material to _____ ."
Again, maybe a bit complex, but there's no reason a city building game can't teach people about the real complexities of cities in an accessible way.
As for railways and transit, did you hear about A-Train 9? It's kinda
difficult to get a hold of outside of Japan and very pricy but it's a
"city" sim with almost exclusive focus on railways. Worth a look.
One thing I can related to is god-awful interfaces. We're trying to
make Synekism's relatively self-explanatory. I personally don't think
we're there yet - being management for the moment only because it maps
a trivial set of abilities. But we have some things we'll try and see.