Question about road works in CH

Hello everybody,

I noticed multiple times, that when reconstructing roads here in Switzerland, the surface / top layer of the pavement is usually laid several weeks / months after the lower layers. For a significant amount of time, the road or sidewalk is left in an intermediate state (see attached pictures). The pictures show an unfinished side-walk, but I’ve seen this happen with road pavements as well, where the wear-layer – which lately is a sound-absorbing mixture of asphalt – is laid well after the previous layers.

Can somebody confirm that this is a deliberate practice or I just happen to come across exceptions where I live? If this is indeed a practice, what’s the reason behind it? Anybody familiar with the norms and regulations in this domain? Thanks ahead for the insights.

Cheers!