TBC Corridor Subgrading

This is my first post here and hope I am able to explain exactly what my question is. I am making a FG & SG corridor surface in TBC v5.40. I used the vertical offset/elevation instruction to build the SG and everything looks great. Except, there is a thin vertical surface area that runs vertically from the SG surface up to the HAL and I wonder if that will affect machine control when I send it out to the field? I feel like this has been discussed before and someone said it would have no effect but I would like to verify this with someone who might have built a model like this before. Thanks.

What version are you running as we made changes in 5.3 2 that helped to minimize those little vertical walls. They should not affect machine control - however if you have the TIN - use the Explode Surface Command to explode the TIN into lines - and join the lines together so that you can easily select them, then you should be able to erase that little wall down the centerline if you want to

I would like to see the file and maybe I will take a look also as that should get erased by the process these days.


I’m running v5.40. This small vertical line is something I’ve seen before which is why I’ve never really used this method for building a corridor. It even shows up with the surface slicer which is why I feel it will affect machine control. I have copied over the HAL and adjusted it to the SG elevations and copied over the corridor templates and made the adjustments that were necessary to get what I need but I have a lot of these to do and am trying to find a faster way of doing things. What is the best way to send you the file so that you can look at it?

Scott Sattelmeier

It sounds like you assigned a material layer to the offset/elevation instruction that you used to drop down to the subgrade. There should not be any layers checked in the instruction. You should NOT see a line in the template graphics that goes from FG to SG.

Gary is right on that one Scott - I misread your post - thinking you were using Subgrade Adjustments not Corridor Instructions - What Gary is saying is that where you create the instruction to drop your CL at FG elevation down to subgrade, that instruction should not be assigned to a Material Layer at all. Same for EOP drop Downs and Shoulder drop Downs - then when you add your Connect Instructions or whichever instructions you are using to create the subgrade surface - tag those as Subgrade Material Layer and you wont have the spike at the CL


That’s what is was, I knew it had to be something simple. Thanks for the help!