I use GPS on many jobs, even when I don't think it's needed.?ÿ Sometimes it makes solo recon for remote points a bit easier
I haven't run a TS in many years. But then we work in the big open.?ÿ
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Internal accuracy of your control points is what matters most when it comes to construction.
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Its important to shoot all targets from one station using both faces if possible. More stations and time between shots makes your internal accuracy worse. Check your prism bubble if your shooting points into ground (nails/rebars etc). You can mitigate prism bubble error by turning prism 180 around between shots and shooting the nails twice averaging the result.
More shots do not make you internal accuracy worse, they give you a better estimate of it.?ÿ Just because you burry your head in the sand does not means something is not happening.?ÿ As others have pointed out, control is the most important part of layout.
Also, ditch the prism pole for control work.
I live and work in a place that has legally defined Low Distortion Projections. Unfortunately, few surveyors are taking advantage of them. Most construction projects are still based on local coordinates or scaled to ground state plane.?ÿ Nevertheless I'll set up project control in the LDP and shift the project onto it - commonly by the use of xrefs.
I'll set up control offsite where it won't be disturbed by the construction - typically across the street for site work - and rely on resection for instrument positions to stake out from.?ÿ?ÿ
Also, I was under the impression you were better off with site coordinates that look nothing like State plane to avoid any future confusion?
This is a common misconception perpetuated over the years.?ÿ I've been producing products exclusively in SPCs (at ground) for 15+ years and have never once heard of any issues. All state projects in my area follow this protocol as well.?ÿ Most companies doing similar work in my area do the same.?ÿ There are a few of the super large firms in our area that are hamstrung by HQ and still have to create projects with odd false northing and eastings.?ÿ It works, but it is increasingly uncommon and most surveyors I know despise it.
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The benefit of coordinates that don't look like SPC is in cases when somebody takes true SPC and scales coordinates instead of distances to move from grid to ground. As long as the metadata explains what was done and everyone is careful to understand, it doesn't matter.?ÿ But lopping off the high digits of the altered coordinates so they don't look like SPC can keep someone from misusing them and creating problems.
The benefit of coordinates that don't look like SPC is in cases when somebody takes true SPC and scales coordinates instead of distances to move from grid to ground. As long as the metadata explains what was done and everyone is careful to understand, it doesn't matter.?ÿ But lopping off the high digits of the altered coordinates so they don't look like SPC can keep someone from misusing them and creating problems.
I understand that age old statement but do not agree with it.?ÿ Anyone blindly using coordinates as SPC has no business using them. I haven't had any issues in 15+ years of using data in this way.?ÿ Also, I have not heard of any State or City projects in my work area having any issues.?ÿ It might be a regional type thing as well, not sure.
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There are a few of the super large firms in our area that are hamstrung by HQ and still have to create projects with odd false northing and eastings.
Back in the day my HP48gx with SMI couldn't carry enough digits to work with state plane. So you had to truncate the numbers. Later versions of SMI fixed this, but it was a real thing for a time. That is one of the ways these things get started.?ÿ
The benefit of coordinates that don't look like SPC is in cases when somebody takes true SPC and scales coordinates instead of distances to move from grid to ground. As long as the metadata explains what was done and everyone is careful to understand, it doesn't matter.?ÿ But lopping off the high digits of the altered coordinates so they don't look like SPC can keep someone from misusing them and creating problems.
I understand that age old statement but do not agree with it.?ÿ Anyone blindly using coordinates as SPC has no business using them. I haven't had any issues in 15+ years of using data in this way.?ÿ Also, I have not heard of any State or City projects in my work area having any issues.?ÿ It might be a regional type thing as well, not sure.
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We've worked with dozen's of engineering and surveying firms doing the DOT thing. From design to build no one I've ever heard of was confused. Like you say,,,,,maybe a regional thing. The system became much more useful with the advent of CAD. Now it's so simple to scale in ortho's, guads, gis, whatever you need and your still "on ground".?ÿ
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Anyone blindly using coordinates as SPC has no business using them.
From '97 to '04 I worked for an outfit that did a lot of large subdivision development. Most commonly the projects would be on a local coordinate system, but some times a scaled to ground from state plane. The work flow would go like this:
1. Control would be established, topo collected, and boundary monuments recovered. Basis of Bearing at this point was either assumed, hand compassed, or, sometimes, state plane.
2. A topo base map would be prepared with planning level boundary resolution and sent upstairs to engineering.?ÿ
.
.
.
a year, or two, or three passes?ÿ ?ÿ ?ÿ
.
.
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3. The project, now designed, comes back downstairs for construction staking. A great many of the wood hubs and PK nails previously set for control have turn to dust so a whole new set of control has to be run, more or less on the old coordinate system, with luck.
4. Staking and construction begins ......control is destroyed and replaced daily, but rarely if ever does any of that get back to the office.
....... now the fun really starts
5. The platting department (one particular guy who specialized in putting the plats together) takes the?ÿ project coordinate system (the one that came downstairs, sans any of the control recovery and rehabilitation) and rotates it on to some logical basis of bearings - ie/ holding a line of some adjacent earlier plat for which monuments had been found - and produces a exterior boundary record of survey as required by local law, and the plat itself. This usually takes a few months to get approved. When ready, he pumps out a set of coordinates for staking of the boundaries and lots. Those coordinates look just like the "project" coordinates, only they are rotated. They have the same numbers and descriptors. For the most part the control points listed no longer exist. The file names and printouts all carry the same project numbers as the project control.?ÿ
Believe me, it was a cluster-Fxxk, every dxmx time. Under these conditions we would have welcomed a coordinate shift at a minimum.?ÿ Granted, there are a lot of other ways this could have been managed - but truncating the coordinates is the one way that this one guy could have taken independent action.?ÿ ?ÿ ?ÿ ?ÿ ?ÿ?ÿ
Also, ditch the prism pole for control work
I try to use a peanut prism as much as possible when practical ?ÿHaha
?ÿ
Anyone blindly using coordinates as SPC has no business using them.
From '97 to '04 I worked for an outfit that did a lot of large subdivision development. Most commonly the projects would be on a local coordinate system, but some times a scaled to ground from state plane. The work flow would go like this:
1. Control would be established, topo collected, and boundary monuments recovered. Basis of Bearing at this point was either assumed, hand compassed, or, sometimes, state plane.
2. A topo base map would be prepared with planning level boundary resolution and sent upstairs to engineering.?ÿ
.
.
.
a year, or two, or three passes?ÿ ?ÿ ?ÿ
.
.
.
3. The project, now designed, comes back downstairs for construction staking. A great many of the wood hubs and PK nails previously set for control have turn to dust so a whole new set of control has to be run, more or less on the old coordinate system, with luck.
4. Staking and construction begins ......control is destroyed and replaced daily, but rarely if ever does any of that get back to the office.
....... now the fun really starts
5. The platting department (one particular guy who specialized in putting the plats together) takes the?ÿ project coordinate system (the one that came downstairs, sans any of the control recovery and rehabilitation) and rotates it on to some logical basis of bearings - ie/ holding a line of some adjacent earlier plat for which monuments had been found - and produces a exterior boundary record of survey as required by local law, and the plat itself. This usually takes a few months to get approved. When ready, he pumps out a set of coordinates for staking of the boundaries and lots. Those coordinates look just like the "project" coordinates, only they are rotated. They have the same numbers and descriptors. For the most part the control points listed no longer exist. The file names and printouts all carry the same project numbers as the project control.?ÿ
Believe me, it was a cluster-Fxxk, every dxmx time. Under these conditions we would have welcomed a coordinate shift at a minimum.?ÿ Granted, there are a lot of other ways this could have been managed - but truncating the coordinates is the one way that this one guy could have taken independent action.?ÿ ?ÿ ?ÿ ?ÿ ?ÿ?ÿ
That's pathetic and absurd, frankly it wouldn't matter what system the project started with if they change it in the middle once or multiple times. There's no fixing that.
?ÿ
Anyone blindly using coordinates as SPC has no business using them.
From '97 to '04 I worked for an outfit that did a lot of large subdivision development. Most commonly the projects would be on a local coordinate system, but some times a scaled to ground from state plane. The work flow would go like this:
1. Control would be established, topo collected, and boundary monuments recovered. Basis of Bearing at this point was either assumed, hand compassed, or, sometimes, state plane.
2. A topo base map would be prepared with planning level boundary resolution and sent upstairs to engineering.?ÿ
.
.
.
a year, or two, or three passes?ÿ ?ÿ ?ÿ
.
.
.
3. The project, now designed, comes back downstairs for construction staking. A great many of the wood hubs and PK nails previously set for control have turn to dust so a whole new set of control has to be run, more or less on the old coordinate system, with luck.
4. Staking and construction begins ......control is destroyed and replaced daily, but rarely if ever does any of that get back to the office.
....... now the fun really starts
5. The platting department (one particular guy who specialized in putting the plats together) takes the?ÿ project coordinate system (the one that came downstairs, sans any of the control recovery and rehabilitation) and rotates it on to some logical basis of bearings - ie/ holding a line of some adjacent earlier plat for which monuments had been found - and produces a exterior boundary record of survey as required by local law, and the plat itself. This usually takes a few months to get approved. When ready, he pumps out a set of coordinates for staking of the boundaries and lots. Those coordinates look just like the "project" coordinates, only they are rotated. They have the same numbers and descriptors. For the most part the control points listed no longer exist. The file names and printouts all carry the same project numbers as the project control.?ÿ
Believe me, it was a cluster-Fxxk, every dxmx time. Under these conditions we would have welcomed a coordinate shift at a minimum.?ÿ Granted, there are a lot of other ways this could have been managed - but truncating the coordinates is the one way that this one guy could have taken independent action.?ÿ ?ÿ ?ÿ ?ÿ ?ÿ?ÿ
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That was more or less the same that I??m accustomed to; start with boundary and topo on SPC then later when construction starts we would establish a control line on a local coordinate system. Just made sure anyone doing any layout had the localized job.?ÿ
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I??m starting to think scaled coordinates must be a regional thing. Guess it depends if your in a flat region or the mountains? Also, I couldn??t imagine doing any layout with the gps unless it??s for a house, even then only for clearing or digging footers. Especially since it seems like everyone wants layout in the thousandths anymore. ?????ÿ
I??m starting to think scaled coordinates must be a regional thing.
In the Pacific Northwest there is just too much tree cover to routinely use GPS. The bulk of survey work is still done with the total station. There are plenty of outfits around here that do not even have GPS.?ÿ It is convenient with the total station to work, even when state plane has been established, without a projection. So a lot of jobs get scaled to ground. It was, for a long time, the Oregon DOT's policy to do so.
A while back - over 10 years ago - ODOT came up with the low distortion projection setup, which allows working with a total station, no projection, no scaling, without significant differences. Nevertheless a lot of outfits continue the old practice of scaling state plane to ground, "because that is the way they have always done it". Grrrrrrrr.?ÿ ?ÿ ?ÿ?ÿ?ÿ
