AutoCAD Civil 3D

[#1]

Haven't really done to much with corridors, not sure best way to tie the end of the corridor into existing ground. See image

[#2]

One method is to draw a featureline along the end of the corridor and use a grading to the EG. 

[#3]

Sjg, that depends. By your image it looks like your road just ends, perhaps to be continued ar a future date. Is this the case? Or is it supposed to tie back into an existing road which maybe isn't shown. Your answer depends on what you want to do there.

In most cases I just leave it as-is without bothering to do any cleanup. The extra work is often pointless unless it's your intent to render this project or if you NEED finished contours.

[#4]

We are going to show it as possible future extension, but most likely will never be extended. So I would like to show finished contours

[#5]

Then Jeff's suggestion is about all you can do. It's pretty much what happens in the field anyway. Paste the corridor and grading surfaces into a new composite surface for your finished model.

[#6]

I have used a M&O sub on the end set to match slope and 0.0001 thickness.

[#7]

Aside from using a grading you can also treat the end like an intersection by creating an alignment representing the end of the road, sampling the corridor surface and either applying an assembly to the alignment or create a grading from a featureline generated from the alignment+profile. It's probably a prohibitive amount of work but it is an option.

[#8]

I will probably just go with Jeff' suggestion and generate a feature line and gradings.