I used to work graveyard or rotating shifts often and on the way home I'd see workers on the highways often. During the summer is the best time to repave highway roads, and they do it at night time since there is significantly reduced traffic. You can see start time for the construction is 12am on your attached pics. High traffic roads are usually repaved yearly, I think they just add an extra protective layer, in Ontario they got bad winters so it's important. Whether or not they will do other stuff during this time I dunno but just sharing my anecdotes.