Not just that, it's also expectations. Traffic runs on a stack not only of rules, but also of cultural conventions. And both rules and conventions exist not onl

Not just that, it's also expectations. Traffic runs on a stack not only of rules, but also of cultural conventions. And both rules and conventions exist not only defining the dos and don'ts for drivers but also defining those of traffic engineers. When we drive in a different country we know that the driving rules are slightly different. We suspect that the conventions for driving are not quite the same. But the differences in rules and conventions of road design are mostly invisible. We may notice the most glaring differences like preferring roundabouts vs preferring crossings, but the large majority of those design principle differences, they are so close to invisible that we expect our expectations to still work. But they don't. Everything just feels subtly off, and sometimes there's a large difference standing out and we just declare that badly planned. Even when it's in fact perfectly in line with local expectationsand usage patterns, and works just fine (except for the confused foreigner). We notice a few standout differences and then blame every bit of traffic badness we encounter nonetheless on the few differences we consciously notice. The parts that work well are usually completely invisible, because traffic, in our perception, only exists when it's bad. Rules/conventions on the design side exist for and can differ in just about every aspect, down to draining angle of road surface (do you drain symmetrically or to one side? Do you switch to draining to the inside in a curve? What about softer curves, sharper curves? A consistent threshold is very valuable, but if one country has a different consistent threshold than the other it feels "wrong" to everybody cross-driving even if no side is objectively better). Or the general shape of curves, some places have strict rules for keeping the second derivative of direction as flat as possible, with few, definitive jumps, others prefer a gentleness above all approach.