Linestrings - standards

I feel silly asking. When I first started using Trimble (coming from using agtek) the other people in my company (they are former surveyors) use horizontal Linestrings for every elevated line (besides contours) but I have seen videos saying to use vertical (from the tabs). Seems like this is a much faster way…aside from needing to correct arcs from time to time. What is the best use?

Also trying to create some standards for myself - things to look for that our field guys need put into a model etc. color standards and feedback on this?

1 Like

Personally, I use VPI’s 90% of the time when elevating linestrings since it is much faster. Just remember that VPI’s are based on the distance along a linestring (much like stations & elevations along an alignment). Horizontal nodes are based on coordinates (XYZ). So just don’t use the CAD grips to adjust your lines if you’re using VPI’s, cause that will mess you up.

The surveyors may have good reason to using horizontal nodes when staking linework in the field, this was true for the last company I worked for. I think it was just more convenient for them.

As for color standards, I would get with the guys running the instruments to see if there are colors they don’t like so you can avoid them. I know yellow is hard to see on their data collectors. Also, keep line names short because their displays are sometimes limited as to how many characters show up on the screen. Hope this helps.


In my opinion there are plusses and minuses to both methods and I use them both at different times. Using only the horizontal tab to input elevations is convenient if all of your vertical elevation points happen to land on horizontal points. Also if you are creating a linestring by clicking and snapping on to points and/or other lines the command will put the elevations into the horizontal tab by default. Another benefit in my mind of having the elevations in the horizontal tab is that when you are editing the linestring horizontally it displays all the elevations in the plan view.

I find the vertical tab to be very convenient if I already have a 2D linestring and just need to add elevations to it to make it 3D and also if the vertical info for the line is more complicated than just elevations at all the horizontal points.

One thing I am very cautious about is not mixing both methods on the same line. It is very possible to have an elevation assigned in the horizontal tab and a different elevation assigned in the vertical tab to the same exact point along the linestring, which of course will almost certainly not give you the result you wanted.

I’m remembering at some point somebody had a TML to switch a linestring between the two methods but unless it was rockpile (I don’t think it was) then the TML likely won’t work anymore with all the changes to TBC.


I try not to send out VPIs as a general rule. I will use the slope intersect function to quickly establish hi/ lo points, but then I replace the VPI with a horizontal node. RPS would advise never breaking and joining linestrings after they are elevated because TBC adds VPIs at break points in an “unpredictable” manner. However, I find that I’m always going back and tweaking or updating a model with revisions, and, if you stick to horizontal nodes as a rule, any VPIs showing up on a linestring are more or less a red flag for something that needs cleaned up.
Another item to note is that TBC is in a different development silo than WorksManager, Siteworks, and Earthworks, and some of the VPI functions of TBC linestrings don’t always show up properly in the field software. This is especially true if you are running older versions of field software.

As to standards, I would advise leaning toward the National CAD Standards where possible.

1 Like

I think it depends more on how you prefer to build your models. I pretty much try to stick to either fully horizontal or fully VPIs on a line and only manipulate linework with grips when its 2D to avoid any issues with VPIs moving, otherwise it’s back to the horizontal tab or the trim/extend/break line commands. I personally have not run into or seen any issues like Mr. Hufford above has with breaking elevated linework and having an unpredictable VPI added in but I’m sure that is a YMMV thing.

I will caution you though, things become interesting when you start mixing horizontal and VPIs on a line. TBC will adhere to the horizontal elevated nodes and ignore the VPIs which can get real fun to track down busts if you’re not familiar with that issue so best to stick to one or the other for each line and not mix them if possible.