Today I am going to talk about how the software puts together a corridor model. I am not talking about the fact that I need to have an alignment profile and assembly to build a corridor, I am going to go delve deeper, or maybe shallower depending on your point of view. A corridor model has three basic parts that make up its construction, points, links and feature lines(There is a fourth component called shapes, but the model can be built without those so we will come back to them later.) Cross sectionaly the model is constructed by points(whose location is determined by the VBA sub-assembly), those points are then connected together by links. Along the profile direction the model is built out by placing the assembly along the PGL at a specified spacing Civil 3D calls frequency. The rest of the model is then built out by playing connect the dots from point to point, these connections are called Feature Lines.

The software connects the dots of like coded points along the gaps, if no matching code is found(Such as when you make a transition from having sidewalk to just a grass buffer at roadside) at the next frequency specified branching control determines what choices the software will make. There are two options for branching: inward or outward, just like it sounds inward branching forces the feature line to connect to the next inward point it finds, outward the opposite. The branching control is found on the feature lines tab of the corridor properties dialog box.

I think my rambling has gone long enough for another post. Check back in for the exciting conclusion, if I haven’t already made you fall asleep at the keys.