What I've heard (with regards to Irish roads) is that it's several wet months each year where the ground temperature frequently goes above and below zero degrees.

So the water keeps filling any small cracks, freezing and expanding, then defrosting and refilling the now bigger cracks. There's many days in the winter where this process might happen several times over a single 24 hour cycle.

It's basically the worst possible scenario for road longevity, or any kind of buildings.

However, while this sounds plausible, I don't know if it's actually true. I haven't heard it confirmed by a civil engineer.