An InRoads user had a question for Mark on surfaces created using Roadway Designer:

Hello Mark!

It was good to see you at Bentley Bash a couple weeks ago; I hope you enjoyed it as much as I did!

Today I have a question about the surfaces that are created in Roadway Designer. I will try to break it down so that my thoughts make sense.

Task: Obtain contours for proposed culvert.

I have: Existing surface, almost-centerline of proposed culvert (to serve as alignment for corridor), design parameters (culvert bottom widths and slope to existing surface).

I've managed: To create templates that depict design parameters (although I need to review point types), to create the corridor and modify transitions, and finally to create the surface of the culvert (which because I used end conditions should match to existing surface-right?)

Question/s: How can I merge the new culvert surface into the existing to make a whole proposed surface from which I can display proposed contours? Or do the corridor surfaces typically stand on their own and my task is accomplished only by drafting (display proposed contours and hide existing in that area)? Or do I have to manually clip ('manually' sounds silly, this being InRoads) the existing surface to be able to use the Merge Surfaces tool and insert the proposed?

Thank you for your time!

Sincerely,

Alejandra 

Here is the Zen Dude's response:

Hi Alejandra!

It was good to see you at the Bentley Bash, too. I always enjoy participating in the Bashes both from the perspective of learning and teaching others. 

Now, on to your question:

I'll go through a little made-up example so I can discuss this. I could really answer this question much more simply, but I wanted to take this opportunity to capture some additional thoughts about this if only because I've never documented it before. (Plus I just enjoy recording my thought process for others ; )

Okay, so I have an existing surface and will work in a little corner of an intersection of two roads. First, I viewed the existing contours in the cyan and medium blue at a 1' interval.

Then I just drew a random shape in MicroStation (in green ; ) that I'll use to create a flat area. It wasn't completely 'random' since I drew it at a specific elevation that was slightly below grade in that area, and I drew it in such a way as to tuck it against the existing side slope so that my new design slope would cut up the side of the existing. The way I'm doing this is starting with a 3D MicroStation line, but I could have also used a 3D Feature in an InRoads Surface DTM if I had one there. But the process is the same regardless of where the 'source' 3D is located.

After I created my grading area, I used the Generate Slope Surface command to develop the surface DTM. I use this command for a couple reasons, but primarily because I will develop precise side slopes that exactly tie into other surfaces; and in this case the Existing surface. I'm not going to go through this tool, but if you are not intimately familiar with it, you should take a closer look at it.

From this tool, I created a Grading surface that starts at my MicroStation 3D bottom and then slopes either up or down as needed at the grades defined as the Cut Slope and Fill Slope fields. This tool can develop three different surface Features - Transverse (side slope breaklines), Source (the Feature or graphic that the slopes are originating from), and the Catch Point (this is the precise daylight and tie-in to the Existingsurface).

Now, getting closer to actually answering your question; if you view the Contours from the new Gradingsurface, you'll see that the new contours tie perfectly into the Contours from the Existing surface.

As far as the presentation of the final display, some of this depends on the CAD Standards of where you work, and you really need to ask this question to the person or department that controls the drawing standards. But if you don't have well-established presentation standards, here is the usual direction that most companies and agencies take.

You can see here that viewing both the Existing and new Grading can create a muddy appearance in areas where there is dense contouring. This makes the resulting drawing difficult to read.

It's very common to view the Existing contours in one MicroStation file and the new Grading contours in another MicroStation file. Then the final sheet drawing is constructed by referencing in the Existing DGN and the Grading DGN, trimming and clipping the outer edges of the referenced DGN to fit on the sheet. As these files are referenced, MicroStation has the ability to change the Symbology of the referenced line work. This is very often done to the existing information in order to make it less prominent and thereby making the design display more prominent. This can also be done through the plotting mechanism, but it's often very nice to see it in the MicroStation drawing too.

Once the drawings are referenced to the sheet file, the contours, if they are viewed at the same Interval, will tie together perfectly and become more readable.

Sometimes, to make it even more readable, the MicroStation Line Style is also changed, making it dashed or thinner. All of this is done to produce a drawing that is clearer to read and present the information with less ambiguity.

Now, all the while, you still have two distinctly different DTMs, the Existing and the new Grading. But they tie together perfectly in every way at the limits of grading or the daylight locations.

Beyond this, there are some users that want to create a 'Final' surface that shows what the completed work will look like. This is desirable in a number of instances and includes visualization of the completed project and during phasing situations where further grading will be done. But understand this 'merging' of the Existingand new Grading is not required for earthwork quantities, reporting, or construction drawings (unless your CAD Standards specifically state this).

If you want to develop a Final surface like this, the InRoads > Surface > Edit Surface > Merge Surfacescommand will stitch any two surfaces together for you. The command doesn't modify the Existing or theDesign, and creates a third Destination surface that becomes the Final combined surface.

From this merged Final surface you can View Contours of the combined surfaces.

You can see in the Feature Properties that it just adds the Grading surface information to the Existingsurface information.

The Merge Surface command (with the appropriate settings toggled on or off) takes all of the Existingfeature content and pushes it into the Destination surface.

Then it maps the outer limits of the Grading surface onto it.

And then, like a cookie-cutter, it chops out the Existing features from the Destination surface

It's left with all of the Existing surface Features and a hole. (Just as a side note, it doesn't have to clip, remove or trim surface Features that are set to Do Not Triangulate since they don't affect the resulting triangulated surface model.)

That hole is then filled with the Features in the new Grading surface.

And voila!! . . . a Final surface!!

So to summarize, you don't have to merge your existing and design surfaces to do quantities and create plan sheets. And in fact, it's generally not done for those purposes.

I trust this helps!! But if you have any questions on anything that I've mentioned here, please feel free to let me know. 

Civilly yours,  

-zen