[NSFL]

The "what you believed as a kid" thread got me thinking about my childhood. As a kid, we used to take a lot of road trips back and forth between Calgary and Regina, and incidentally, still do. But driving on the highway, I noticed that if you got too close to the side of the road, you'd hit a rough patch and it would make a really awful grating sound. Like, the rough patch is "built into the road" right beside the line. I hope you know what I'm talking about.

But yeah, one day, my dad asked me why the road was made like that. My answer: it's so if you're driving at night, and if you kinda doze off, when you start to leave the road, the sound would wake you up. But then my dad was like: what prevents you from turning into oncoming traffic then? And that pretty much messed up my theory.

So to ask CP, why is there that rough patch that makes that awful sound? I'm sure someone here must know. I've tried google, but didn't have much luck.