I've never figured out how player contributions work on those highways. The very first section seems to be all your responsibility and, until you finish it, no contributions show up from any other players. Once you finish it, though, the flood gates open and you get bunches of messages about contributions. For me, the road got completed all the way to the Craftsman in just a few minutes. Since then, the progress gets about halfway along, then stops and waits for me to complete the rest.
I built that first section you mentioned and all the road was completed up to the Distribution center. I have built three more roads past the Distribution Center. For me, it seems the likes will is calculated as to how much you are using of resources to build the road + bonus likes from the other road builders and then the likes you get from the people using the road. I don't think you get much extra for being the one who completed the road if you did not put a lot of resources into it.
"A sweaty player is usually a player who goes so try hard his hands might as well be sweating from the try hardness."Sweaty!?!?