Since I made my diorama, something has bugged me. The road lanes seemed too wide. Yesterday, I realized they seem too wide because they are!
Right now they are 12’ scaled to 1:64. But when I look at Google maps at nearby towns, I noticed something odd. The lanes for the highway are significantly wider then the lanes in a town. In fact, I think 12’ wide is on par for hwy lanes, and town roads are probably 8’ wide (cars tend to be 6’ wide). So mystery solved! No idea what I'll do with this new info though...