Today a friend of mine made me realize that roundabouts have “perfect” road markings around them and i started wandering how a machine would go about making a circle without a compass-like system. So i tried google but every result led to either a janky home made compass or some sort of hand-drawing technique. I assume it should be possible to draw a circle knowing the radius in an analog system without a compass but i can’t figure out how. Plus i don’t know how the physical structure of a roundabout is made to be round and that is even weirder to think about.
TLDR: How are roundabouts and round road markings made?
Not sure about this, but the machine that paints the line probably has its steering/turning circle set to the required radius/diameter/angle and then just drives in a circle, same as if you held your steering wheel just off centre, eventually you’d end up back where you started. If it’s a few centimetres off, it probably doesn’t matter.
Either that or it just follows the edge of the thing it’s drawing a circle around