We have always drafted our surveys showing the power (or "utility") poles, and drawn in the overhead lines between them. This was drawn generally so that the client or user could see where what poles were connected. There are a few things that are starting to concern me about this practice... In downtown areas, they are starting to build with no setback, and are asking specifically about power lines. So much so that we have done some special line exhibit maps where we actually located every individual line. This is getting to be common enough that I am concerned that someone, someday may take the lines that we draw just between poles and assume that is the actual line, and design a building to close to the power line. That and in scenarios where lines were connected to another line, but near a pole, we would just show it going to the pole. (like "A" below)
Is this a valid concern? If so, what kind of CYA note should go on a map that shows overhead lines just between poles. 
Interesting question, and since you brought it up, I would say it is a valid concern with regard to the work that you are doing. I, too, show the generalized wire runs on plans, although where the wire connects to another wire I would not snap it to a pole. I figure a wire location that is +/- 3' by measurement is better than one that is definitely 5' - 10' feet (or more) off by snapping to a pole.
Maybe add a note to your plan like this, "Overhead wires are shown in generalized locations, showing the wire run connections between utility poles and other structures. The locations of individual wires were not measured precisely, and their representation on this plan should not be relied upon where precise clearance distances from overhead wires are required."
You might want to use separate CAD layers and line types to distinguish generalized wire runs from precisely measured wires, and include that distinction in your legend.
I would not show overhead lines unless specifically requested to do so. This is how I show connectivity between poles when I have not been requested to show overhead utilities. I will also limit the legend to refer to Utility Poles. Sometimes I show pole numbers next to the symbols...other times I don't.
I figure either they don't need the information, or they need very detailed OH utility information.
"The arc of the moral universe is long, but it bends toward justiceÛ
-Martin Luther King
"The history of surveying for design in urban areas is long, but it bends toward showing more and more accurate 3D dataÛ
-Me
The purpose for a survey defines the detail that is shown.
I would believe that a survey in downtown area if the client has design to place something into the air that would interfere with existing utilities or other structures, then those items need to be shown in whatever detail necessary.
I have performed overhead utility surveys where minimum clearance under each line was required as well as the connectivity. This was important to determine the best location of a staging area for materials and large construction vehicles such as cranes.
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I think PPM has brought up a good point that will likely be an issue for some of us in the future. It's probably already been addressed by others. Peter's note is definitely headed in the right direction -
Peter Lothian - MA ME, post: 423133, member: 4512 wrote: "Overhead wires are shown in generalized locations, showing the wire run connections between utility poles and other structures. The locations of individual wires were not measured precisely, and their representation on this plan should not be relied upon where precise clearance distances from overhead wires are required."
Slicing hairs, I'd leave out the word "precise" since it's so subjective.
Maybe something like:
"Overhead wire linework indicates the existence of overhead wire(s) in the vicinity at the time of survey. This linework does not represent the position, quantity, or type of overhead wire(s)."
While that note is pretty much disclaiming everything about details (and hopefully liability related to details), you are still on the hook for existence of OH wires so review your project photos to make sure nothing was missed. We all hear about crane operators getting electrocuted from time to time - I wouldn't want to have missed an OH wire that should have been shown on the plans but wasn't.
Your client may very well need more info - if so you can tailor the work effort, cost, & the note to meet their needs.
We often locate lowest sag point and elevation at each end but not X,Y locations. Can see it in the near future though.
JKinAK, post: 423209, member: 7219 wrote: I think PPM has brought up a good point that will likely be an issue for some of us in the future. It's probably already been addressed by others. Peter's note is definitely headed in the right direction -
Slicing hairs, I'd leave out the word "precise" since it's so subjective.
Maybe something like:
"Overhead wire linework indicates the existence of overhead wire(s) in the vicinity at the time of survey. This linework does not represent the position, quantity, or type of overhead wire(s)."While that note is pretty much disclaiming everything about details (and hopefully liability related to details), you are still on the hook for existence of OH wires so review your project photos to make sure nothing was missed. We all hear about crane operators getting electrocuted from time to time - I wouldn't want to have missed an OH wire that should have been shown on the plans but wasn't.
Your client may very well need more info - if so you can tailor the work effort, cost, & the note to meet their needs.
You got my point exactly. The unintended use of my map. We to have done quite a few additional maps to a topography where they want LOT of details on the overhead lines. And we do it, but it isn't free and a large percentage of the original contract. I am just worried about the topo's that we sent out and DIDN'T get asked to go back and locate actual line locations, as well as the ALTA's and other types of maps where we (a surveyor) would not think it necessary but someone else (client or another user) assumes it was part of the work. So, in a sense I am looking for a standard note for the map, or line to add into the contract. And I like this note for a start already. :clink:
