AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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Active Member
jwilkerson
Posts: 9
Registered: ‎11-05-2008
Message 1 of 21 (235 Views)

Calling all surveyors, I need your opinion on something.

235 Views, 20 Replies
03-26-2009 08:20 AM
I am a civil engineer (as well as the CAD guro at my company) and I have been having issues with our surveyors not get enough shots in the field. Specifically, when they shoot the top X and bottom X of ramp and driveway curb transitions, they only shoot the TC elevation and not the adjacent flowline and edge of gutter. This causes problems with crossing breaklines (especially around curves) when we go to build the DTM. I understand that these elevations can be found by interpolation but that requires a lot of post processing. I am just curious what the industry standard is on this issue.

Thanks,

Jeff
Distinguished Contributor
davevoith
Posts: 469
Registered: ‎08-09-2007
Message 2 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 08:38 AM in reply to: jwilkerson
For accuracy I assume you would want to pick up tc, ep, clrd, ep, tc and add them to your surface as breaklines. But for most Topos Top of Curb and Road Centerlines are sufficient.
Distinguished Contributor
nostupidquestions
Posts: 471
Registered: ‎11-17-2005
Message 3 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 08:50 AM in reply to: jwilkerson
we have the same problem with surveys. all back of curb shots with no edge of pavement shots or maybe a centerline shot every half mile. you would think that when the cad guy builds the contours he would notice that they are not reflecting what is really out in the field. at one time i made a list of things we require from the surveyor but the problem is the property owner usually has a survey when the come to us.
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*Christof Lambrecht
Message 4 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 11:03 AM in reply to: jwilkerson

jeff,

we use GeOpus & Micostation Fieldworks/Inroads,
both let us code a set of parallel lines just by measuring first a masterline
and then for each parallel line we take one point that defines the offset
horizontal & vertical, next you take only shots on the masterline & when
processing the data the parallel lines are constructed. (see pdf Code PP for
GeOpus or TMPL - template for Inroads)

I took just a look at the new items on surveying in
C3d rel2010 but this code isn't there yet.

In the FBK commands there is an offset command but
as far as I have read it's only a 2d offset ...

 

When your surveyors should measure the
adiitional points as in the pdf to build the parallel lines and they add a note
so you could find these points easily in C3d couldn't you then, by using the
standard Acad offset command, create this parallel lines just by offsetting the
measured figure through the extra measured points?? Can this be done in
C3d??

 

chr. 


style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
I
am a civil engineer (as well as the CAD guro at my company) and I have been
having issues with our surveyors not get enough shots in the field.
Specifically, when they shoot the top X and bottom X of ramp and driveway curb
transitions, they only shoot the TC elevation and not the adjacent flowline
and edge of gutter. This causes problems with crossing breaklines (especially
around curves) when we go to build the DTM. I understand that these elevations
can be found by interpolation but that requires a lot of post processing. I am
just curious what the industry standard is on this issue. Thanks,
Jeff
*Christof Lambrecht
Message 5 of 21 (234 Views)

pdf from previous post

03-26-2009 11:07 AM in reply to: jwilkerson

c.


style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
I
am a civil engineer (as well as the CAD guro at my company) and I have been
having issues with our surveyors not get enough shots in the field.
Specifically, when they shoot the top X and bottom X of ramp and driveway curb
transitions, they only shoot the TC elevation and not the adjacent flowline
and edge of gutter. This causes problems with crossing breaklines (especially
around curves) when we go to build the DTM. I understand that these elevations
can be found by interpolation but that requires a lot of post processing. I am
just curious what the industry standard is on this issue. Thanks,
Jeff
Active Contributor
dnietubicz
Posts: 41
Registered: ‎10-23-2006
Message 6 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 11:36 AM in reply to: jwilkerson
I worked for a surveyor for about 10 years as the Cad Manager. I now work on the civil side for local government. The main problem I see, is that the guys in the field have no idea what it takes to make a good accurate surface. When I was at the survey firm, I tried having field party chiefs learn how to do cad work. It was funny giving one party chief anothers field notes and having them do a survey. Wouldn't you know it, they complained about the lack of shots just like us CAD guys.

All I can say is to come up with a detailed scope of work for the job. If you want detailed cross sections then tell the surveyor exactly what you need. Here is an example of what I would ask for:

-Need cross sections every 100' from 20' outside r/w to 20' outside r/w. (I prefer this to be stationed)
-Locate top of bank, toe of slope, shoulders (paved and unpaved), back of curb, face of curb, gutter bottom, edge of pavement, crown.
-Locate every utility, utility marker, signs and structures within r/w
-Locate invert of pipes, measure size & note material
-Locate top of headwall and bottom where it meets grade
-Make note of any shots that the elevations aren't any good.
-WHEN IN DOUBT SHOOT IT!!!

If the client has already had work done, then tell them you need additional surveyor work to do the job right. If they don't want to get the surveyor back out, just remind them that it costs money to bring in dirt or haul it away.

Doug
*Expert Elite*
AllenJessup
Posts: 6,176
Registered: ‎05-21-2003
Message 7 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 11:49 AM in reply to: jwilkerson
Those are points that I would have collected when I ran a field crew. As a rule you should not be interpolating them of creating them by offset. If a few are missed on a job that's probably not a big deal. But interpolation and offset only work if it is a new road with all standard height curbs that were installed correctly

If you can't convince you're Surveyor personally then you have to convince his boss to ask that the points be collected. It doesn't take that long even if you don't have a robot.



Allen

"All contours are lies!"
Distinguished Contributor
mdriver1
Posts: 337
Registered: ‎01-24-2008
Message 8 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 12:04 PM in reply to: jwilkerson
It's very common to see this type of laziness amongst surveyors. Dang it's very easy to take the shots! I am a solo licensed land surveyor in the process of gathering the required experience for my PE but have obtained a combined 17 years of experience. I went to engineering school later in life and the board wouldn't accept my 7 years of pre-graduate experience. Oh well moved on.
Anyway I do understand what it takes to make a model and will take shots on gutter (flowline), top face curb and top back curb. It's not that difficult to achieve and the results fair very well. I get called anal for the overkill but hey it's my model and will expect any future employee to follow my protocol. Plain and simple.
I also search deeds back to the creation of the subject parcel no matter how far. Is that anal or overkill? Seems proper to me. Senior/Junior rights come into play and aids in proper boundary surveying.
Maybe you should hire out a surveyor who will take the right shots and let your other guys/gals sit around the office and scratch their butts all day. I think the point will come across when the jobs are being farmed out, data's coming back as you expect and they are not part of it.
You asked for opinions and I have given it to you.
Good luck,
Mark Driver
(the anal surveyor)
Distinguished Contributor
balloonsrise
Posts: 422
Registered: ‎06-02-2006
Message 9 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 12:21 PM in reply to: jwilkerson
I suggest cross-training. The field guys often times do not know the first thing about CAD and have never had to make a good surface. Basically, install the cad software in their brains so they see the connection. It doesn't even have to be intense training, just a good once-over.
Civil 3D 2013
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Active Member
ddacad
Posts: 6
Registered: ‎03-11-2009
Message 10 of 21 (234 Views)

Re: Calling all surveyors, I need your opinion on something.

03-26-2009 12:27 PM in reply to: jwilkerson
Jeff, this is common in many survey firms, but unacceptable. It takes a survey manager that has been thrown into the drafting chair to set policy of what needs to be collected in the field. I'm very grateful that the survey manager in our firm has indeed been in the drafting chair and now knows the problems that are encountered when the necessary data is not collected in the field. (I've also worked at survey firms where it was hopeless to try and convince the survey manger and/or the field surveyors what's neccessary for proper surface creation.) Only shooting the Crown of Road and Back of Curb is not sufficient. This causes interpolation straight from the crown to the top of the curb and doesn't depict the slope from the crown to the curb. The addition of the Edge of Pavement shots will accurately depict this slope.

The "shoot" policy at our firm on roads is as follows: Back of Curb, Edge of Asphalt and Crown of Road (centerline). If we have to produce existing cross sections on drawings, then shots on Gutter (curb flowline) and Face of Curb (top/front) is added to this. The Gutter & Face shots are necessary for accurate cross section depictions, but is not necessary for a typical topographic design survey.

Good luck.

dd
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