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US Survey Foot or International Foot

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(@scott-bordenet)
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I am a big fan of reporting state plane coordinates of all relevant control and monuments on my surveys. I typically dimension on the grid also -but not always. I mostly work in central Indiana where there is little vertical relief and not much difference between grid and ground (a few hundredths to fifteen hundredths in a quarter mile). To me, for a modern survey, coordinates on a known datum are an important part of a survey as they are so easy to retrace. Its ok with me if this is not part of your approach.

I was recently asked why I still use US Survey Foot instead of international feet by a 20 something y/o. I answered because I am a 50 something y/o. I guess I really should switch over.

Who here still uses US Survey Foot and who uses international? Why? Just curious.

 
Posted : 10/10/2024 12:16 am
(@norman-oklahoma)
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I use the Int'l Foot when working in NAD83 in Oregon. The "Oregon Coordinate System of 1983" is so defined in state law. The same law dictates using US Feet when working in NAD27, but I haven't done that in quite some time.

Similarly, Washington State statute law dictated the use of the US Foot - until recently. It was changed to the Int'l foot a couple years back in anticipation of the new NATRF2022 datum.

When the NATRF2022 datum is rolled out for real everybody everywhere will be obliged to use the Int'l foot.

Check out this document, which I found by googling "Indiana Coordinate System":

InGCS-NAD83-DefinitionFile-ApprovedAdopted-20150728.pdf

 
Posted : 10/10/2024 12:25 am
(@not-my-real-name)
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It's the law in my jurisdiction to use U.S. Survey Feet.

 
Posted : 10/10/2024 12:42 am
(@scott-bordenet)
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Oh, brother! Don't get me started on INDOT's low distortion projections. Went from Indiana's two zone SPC's (East and West) to 40-something separate projections. Unless they are working for INDOT, I don't know anybody using those LDP's. Even the county and city DOT's aren't using it.

 
Posted : 10/10/2024 1:57 am
(@mightymoe)
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Use the defined value for Indiana. If that's US feet don't change to international. It could be either a statute or basically an agreement with NGS.

 
Posted : 10/10/2024 2:05 am
(@dmyhill)
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Similarly, Washington State statute law dictated the use of the US Foot – until recently. It was changed to the Int’l foot a couple years back in anticipation of the new NATRF2022 datum.
When the NATRF2022 datum is rolled out for real everybody everywhere will be obliged to use the Int’l foot.

Washington's switch to international foot does not occur until the NATRF2022 datum is declared to be the NSRS. Do not use international foot in WA at this time.

https://www.dnr.wa.gov/publications/eng_plso_nsrs_meters_to_feet_with_nad83.pdf

Disclaimer:

The switch has already occurred, but trust me, it hasn't.

 
Posted : 10/10/2024 2:55 am
(@dmyhill)
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I would make a caveat to this: If there is a new realization that occurs between now and 2026 when the (2022) datum is put into effect, then it may be interpreted that we should be using the international foot.


We are in an interesting place when the PLSO, and the definition of WA North Zone, are calling for US Survey feet, but the code clearly says that the WPCS is Standard Foot.

Just another reason to NOT put coordinates on my maps. Maybe I will just report Cartesian Coordinates and a reference frame, eschewing any mention of WPCS or SPC.

 
Posted : 10/10/2024 3:00 am
(@bill93)
Posts: 9834
 

The type of foot is as much part of the definition of a projection as the false northing and easting. If your SPC or LDP was defined with US Survey feet it makes no sense to try to use Ift, regardless of when or what some official body may say. That would be inventing a new map.

The change in type of foot comes with a new projection definition to go with the new datum.

 
Posted : 10/10/2024 3:56 am
(@john-putnam)
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The SPCs are all defined in meters (along with most published LDPs I'm familiar with). In most survey programs the units don't matter since they are just a matter of scale and be changed back and forth at the push of button. The one exception is AutoCAD which for some reason deals with units in the most backwards of ways.

 
Posted : 10/10/2024 5:20 am
(@pachetti)
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Pretty sure most, I think it's 48 out of 50, state recognize us feet. I could be wrong on the recognition vs. usage.

I work in Oregon, so we all are pretty much on INT FT. Won't be long, based on NGS, that we ALL will be there.

Love reporting coords. Mainly on mons, but still great.

 
Posted : 10/10/2024 7:16 am
(@norman-oklahoma)
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"Oh, brother! Don’t get me started on INDOT’s low distortion projections. Went from Indiana’s two zone SPC’s (East and West) to 40-something separate projections. Unless they are working for INDOT, I don’t know anybody using those LDP’s. Even the county and city DOT’s aren’t using it."

Here in my corner of Oregon, with the Washington State line within commuting distance, switching between zones on a project by project and day to day basis has always been a fact of life. And that switch has always meant switching between foot definitions.

I just don't see a problem with using LDPs. The areas covered are large enough that most surveyors are going to do a vast majority of their work within a single zone. So what if there are 39 more somewhere else?

Nevertheless, I do see that not many people, outside of the DOT, besides me are using the OCRS LDPs. IMO, that is on them, not on the LDPs. I prefer having my grid distances substantially equal to the ground and the grid orientation being within minutes of true north - for zero extra effort.

 
Posted : 10/10/2024 7:28 am
(@olemanriver)
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Here US ft for state plane as well. On NAD83 or NAD27. However some old cities and counties years ago went with international feet. Then switchoback at different times and of course the meters attempt as well.

As long as you are on NAD83 and your legislative or statutes dictate which one to use NGS will still support that. From what I have gained the new datum and projections will only support meters and international feet from NGS. Now I can only assume that the states will write this in but they could be a hold out or so who knows.

Autocad could not handle us ft at all until around 2016. I believe. And as stated above the way it handles units still today is backwards for sure. I have to build a good check routine for surfaces or dwg’s when I send or receive them from others or to others. Here in one zone it’s about 25’ shift so usually easy to catch on imagery. But other states it is small as 4 ft and that scares me more as imagery is sometimes hard to detect from a visual. The chain progressed to us ft. So we all still need to know that but linear distance is not to bad only about 2ppm. It’s using coordinates that are in the millions that bites you.

I am a fan with today’s technology to just use state plane always. There are instances where our average.10 per thousand foot could be an issue but it’s all about what the scope is and such. On boundaries I have done all grid and given the combined factor for reducing the grid distance to ground and make note of the acreage at ground almost always as that is what is being paid for.

 
Posted : 10/10/2024 7:28 am
(@wa-id-surveyor)
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I'm with @dmyhill , WA has not made things easy to follow regarding their statutes as it relates to US/International foot and reporting said info on surveys. Coordinates are very rare on surveys in my primary work area (ID) unless. The lone exception being ITD right of way surveys. For those it's required. Coordinates are usually at the bottom of the list in priority of calls.

 
Posted : 10/10/2024 8:11 am
(@olemanriver)
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This whole discussion brings up a very interesting question. If since Hassler was appointed to standardize all weights and measures that agency has grown and he worked also for what we now call the NGS. How did the different states that where part of the original 13 colonies I understand territories and Texas etc not all be on the same unit of measure at this point in time. I am partial to us ft it just has a nice ring to it. I was not a fan of the metric system at first either. But I did get use to it. I remember some reading from the arguments of South Carolina years ago as they chose international feet. Arizona was another. Some states don’t have it in a statute some do what unit is to be used.

 
Posted : 10/10/2024 9:23 am
(@base9geodesy)
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For NAD 83 only four states (AL, AK, HI and MO) have never legislated a specific foot conversion although in general they all use US Survey Foot. In reality none of this should have happened. From the very beginning with the publication of NAD 83 in 1986 all SPC values should have been in International Feet. On June 30, 1959 the Bureau of Standards (now the National Institute of Standards and Technology) published a Federal Register Notice "Refinement of Values for the Yard and Pound" which essentially created the International Foot and specifically states "until such time as it becomes desirable and expedient to readjust the basic geodetic networks in the United States after which the ratio of the yard equal to 0.9144 meter, shall apply." When NGS connected with the American Congress on Surveying and Mapping (ACSM) (Regrettably now defunct) we had considerable push back from many states that really wanted to keep the U.S. Survey Foot. Ultimately the NGS Director decided to skirt the FRN and stated that the agency would only publish meter values and if any state wanted NGS to publish feet then they would have do it my state legislation, which is exactly what happened in 46 of the 50.

 
Posted : 11/10/2024 4:39 am
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