Creating an existing profile from survey data

[nwray]

Hi all,

I am fairly new to the Civil side of AutoCAD, as I used to work primarily in Map.  I am working on a street rehab project in which I need to take survey points showing existing elevations (centerline, flowline, and top of curb) and show existing profiles in a profile view.  I have no problems setting up the profile view(s) or the centerline alignment, but I am having problems with creating the profiles themselves, and I have a two part question about them

Question 1:

According to the user's guide, the correct way to set up an "existing" profile is by extracting it from a surface, but I don't have a surface to use.  In reading through the various profile types, the best way to set up what I want seems to be by using the profile layout tools, but the help says that a profile layout is supposed to be for a final "proposed" profile, not the existing.  Does this actually matter?  Will I be breaking Civil functionality by creating an existing profile using the profile layout tools?

Question 2:

In reading through the profile layout tools, everything seems to be centered around PVI's.  Even using the "tangent tangent" method to add in points seems to only use the first and last point as controls, with everything in between treated as a PVI.  If you look at the documentation here, points one and four are treated as actual elevations, while curvature occurs at points 2 and 3.  In my case, since what I have is a series of actual points on a surface, each point should be an actual surface elevation with curvature occurring between points and not at them.  What method should I be using to input the points in the profile?

If anyone has some pointers on creating these types of profiles, I would appreciate it.  I am using Civil 2014.

Thanks,

Norm

[troma · Accepted solution]

I recommend you build a surface from your points. Then create a surface profile.

[Joe-Bouza · Accepted solution]

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Question 1:

According to the user's guide, the correct way to set up an "existing" profile is by extracting it from a surface, but I don't have a surface to use.  In reading through the various profile types, the best way to set up what I want seems to be by using the profile layout tools, but the help says that a profile layout is supposed to be for a final "proposed" profile, not the existing.  Does this actually matter?  Will I be breaking Civil functionality by creating an existing profile using the profile layout tools?

Answer: A surface is not needed it only make it easier to update if data points change or the horizontal alignment moves. You could use the layout tool and I don't believe it would cause a problem with other functionality.

Question 2:

In reading through the profile layout tools, everything seems to be centered around PVI's.  Even using the "tangent tangent" method to add in points seems to only use the first and last point as controls, with everything in between treated as a PVI.  If you look at the documentation here, points one and four are treated as actual elevations, while curvature occurs at points 2 and 3.  In my case, since what I have is a series of actual points on a surface, each point should be an actual surface elevation with curvature occurring between points and not at them.  What method should I be using to input the points in the profile?

Answer: There is another method you may have over looked; "By File", all you need is an ASCII file of station elevation Ithink it could be space or comma delimited check help

[ericcollins6932 · Accepted solution]

Create a surface using your survey points. For simplicity sake, under definition go to point groups and  add the all points point group.

Create an alignment everywhere along where you want your EG profile with no labels.

Create an existing ground profile using the alignment previously created to define the path of the profile. Easy peasy.

When you start civil, there are tutorials for this too.

Using profile tools usually occurs after you have created an EG profile and profie view.

[AllenJessup · Accepted solution]

As pointed out. The way you would be "breaking" C3D functionality would be that the Existing Profile would not be dynamically linked to a surface that in turn would update in response to additional data. Other have pointed out that there are other ways to create an Existing Profile.

My suggestion is that since you have existing Survey you should create a Surface from that data. One thing to consider. To get the most representative Surface. You should create Featurelines along centerline, flowline and top of curb to add to the Surface.

Allen Jessup

[nwray]

Hi all,

Thanks for the suggestions.  I was thinking that I might have to create a surface from their survey points, but I wanted to get some other ideas first.  My only question about the surface would be whether or not I have enough point density to make an accurate surface.  I basically only have 7 to 8 points every 25 feet, and the points for the top of curb and flowline are coincident with eachother.  I can probably add a series of points for the top of curb locations - just offset them about a half inch from the flowline points.

Thanks again!

Norm

[AllenJessup]

Looks like you have plenty of data too me. Yes. You'll have to offset those points. Probably the easiest way is to draw a Featureline through them and offset the Featureline. You can exclude the top of curb shots from the point group you build the Surface from and add the offset Featureline. That way there's no need to create more points.

BTW. If the field data is from your own company. They should change their field procedures. We usually shoot the back of curb to allow for the offset.

Allen

[_Hathaway]

Whatever you do, do not make a surface strictly out of points if your planning up pulling any sort of accurate cross sections. You will need to define breaklines in the surface for your cross sections to display accurately. This should always be done by the firm supplying you with the data. If this is not possible than you will need someone knowledgeable in surface and breakline construction to be able to use this data accurately....or as close to accurate as you can get by creating a surface from points only.

[ericcollins6932]

I totally agree with Mike that breaklines are necessary for accurate detail views. If you are just looking for a first preliminary look at the EG profiles though, the breaklines can be added when you get more information or need more accuracy as the profile will be along the points most likely anways.

It all depends on how the points were surveyed - if they were surveyed in a sectional style, the TIN will build as if there were breaklines already. If the surveyor walked each of the profiles and points don't line up in nice little rows, the TIN will be more irregular warranting breaklines to properly define the curb lines, etc.

[nwray]

Again,  thanks to everyone for their help on this one.  To test everything out, I ended up using a different street project where the surveyor supplied us with a working surface (cogo points, breaklines, feature lines, etc).  Using that, I was able to create the various alignments (centerline, top of curb, flowline) that I need and then create profiles and views for them.

My only problem now is that in order to see the various profiles on one view, I need to superimpose them, which removes the ability to automatically label the slopes and grade breaks!  I found many posts on this issue on the forum, and it appears that this is an intentional feature.  It just seems odd to me because I would think that the ability to show multiple profiles (with slopes or other information) in one profile view would be something that most projects would require.  I have ended up using a suggestion to create a "depth" label style that actually calculates the slope and then manually apply this to all of the profiles. 

Does anyone know if there is a way to mark multiple responses as the solution?  I have used all of the ideas presented, and I'd like to give credit to everyone. 

Thanks,

Norm

[troma]

Yes, you can click the "Accept as Solution" button on as many different posts as you like.