Please please please stop thinking of a Site in Civil 3D as a site! It’s not!
In my C3D fundamental classes, I ask my students, “As a group of civil engineering professionals, what do you think of when I say the word ‘site’?” Answers vary but the typical ones are something like, “The project location”, “Project Limits”, “Area where work is to be done”, etc. When I first started to use Civil 3D, that’s what I thought of a site as well. I have some bad news for you, a Site in Civil 3D has absolutely NOTHING to do with location. I don’t think they could have chosen a worse word for this particular concept. I would much rather have it called what it is, a Topology.
“Topology? What is a topology?” That’s exactly why I think it would be better to have that name then “Site”. When someone new to Civil 3D sees the word “Site” they assume they know what it is because, well, about once a week they do a “Site visit” and at the start of any project, they get a “Site survey” done. If they had used the word “Topology” instead, a new user would look at that and, since they don’t know what a topology is, would not make the dumb mistakes I made as I was learning.
So, what is a topology? Well, basically it’s a set of rules that govern how lines (in the case of Civil 3D) behave as other lines change. When alignments and parcels are in the same site, the alignment will subdivide the parcels. When parcels and feature lines are in the same site, the parcels will alter the feature line elevations.
Here it is, my rule of thumb when it comes to sites, “The only time you should put ANYTHING in the same site as anything else is when YOU intentionally want them to interact.” In other words, unless you want these two things to react to each other, they shouldn’t be in the same site.
So, whenever you see the word “Site” in Civil 3D, just scratch it out in your mind and replace it with “Topology”.
p.s. White out doesn’t work so well…