@ted That significantly increases the amount you need to dig though, and might make ventilation more difficult? Though it might be worthwhile anyway. :/
@Angle sure, definitely more expensive if nothing else. But people in cars are less likely to enjoy the sunshine than someone walking. I always believe in optimizing for enjoyment.
@ted Hmm, a good point. Though I personally don;t enjoy sunshine, or at least not direct sunshine - I prefer cloudy days with indirect sunshine. And being underground actually sound kinda cool - especially if there are, like, sunwells and decorative gardens and the like. XD
@ted Step 1. Put cars underground Step 2. Make special pathways for cars Step 3. Make carpooling work well Step 4. Make cars electric Step 5. Make cars driverless Step 6. Call special cars a subway system
(We have electric, driverless subways where I live. It's rad.)