system
Given the following post, respond as if you're commenting on Reddit:
human
[Sonic Adventure 1 and 2] Why are city streets and otherwise public areas and architecture built with strange elements that are impractical for normal people?

Like why are there loopty loops on a highway or lack of safety measures in an indoor amusement park that normal people can't traverse? Why is the government approving these measures? I swear Twinkle Park must have dozens of safety violations.
gpt
In Sonic Adventure 2 we see an actual finished highway (Tails' chasing after the president), and while it's got a few similarities to racing tracks it doesn't have any loops in it.

What's clear is that Speed Highway and Radical Highway are in the process of being built and/or repaired.

This can only mean that, in this world, Highways are prefabbed pieces of concrete. Rolled up into a circle for transport and unfurled once they reach their destination. 

Sonic and friends just happen to be running through the area mid-construction.