Gravel Road Ridges

[Rev. Green]

Ridges sometimes form across gravel roads when there is sufficient traffic. The roads are basically flat with a sprinkling of small stones. The stones group together into bands, about 15cm apart, extending much of the way across the road, with the intervening space almost free from stones. How do these ridges form, and what determines their spacing?

[bobbinwales]

maybe a band forms as most cars follow a certain path so far from the kerb and middle and once a band is there cars tend to follow it and drive there... just like when a track is formed on roads covered in snow????

[jno]

any help?

https://en.wikipedia.org/wiki/Washboarding

[gingejbee]

bobbin...he said "ACROSS" the roads

[sddsddean]

Good old corrugations!! If you want to go into the maths/science of them, try this
https://royalsocietypublishing.org/doi/10.1098/rspa.2020.0323