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Ending the Era of the U.S. Survey Foot
- yathern 7y agoIf anyone else is curious - the "US Survey Foot" was 609nm larger than the US International Foot. Or, 0.0002% Larger.
- whatshisface 7y agoIt would take 41,708 feet for the error to add up to one inch.
- twic 7y agoWhich feet?
- oneplane 7y agoThe non-survey one
- killjoywashere 7y agoThe left ones. Sorry, I'll show myself out.
- hadlock 7y agoMildly surprising that we are not just using meters at this point.
- kbar13 7y agothink renaming a software library is hard? try changing units of measure!!!!!
- oneplane 7y agoI think that's what they did in Canada and it worked out great as far as I can tell (except that they had a silly clock based on 10 hours instead of 12 IIRC which had little to do with metric units and nobody wanted it nor was it compatible with the rest of the world).
- kibwen 7y agoI suppose it depends on what your goals are; despite being officially metric, my Canadian and British friends still seem to exhibit a melange of imperial and metric in everyday life.
- saghm 7y agoI notice sometimes when watching British television that stones are commonly used as a unit of weight, which is interesting because it's imperial, not metric, but I've seen never it used in American contexts.
- moron4hire 7y agoThat's because we don't use the Imperial system. The system we use is called "US Customary".
- Someone 7y ago“1 stone equals 14 pounds” is (also) British. It dates back to Edward III (1350). See https://en.wikipedia.org/wiki/Stone_(unit)#England https://en.wikipedia.org/wiki/Stone_(unit)#England. The idea to use physical stones as reference weights is way older.
- thrower123 7y agoSome metric units work well, and are scaled to human everyday measurements, and some are not.
- beerandt 7y agoBut the time thing goes to show the absurdity of people's frame of reference. The same people that judgingly ask why the US hasn't gone full metric will say how absurd the idea of base 10 time is.
- salgernon 7y agoSaw this here somewhere previously: Sweden did something more insane: Högertrafikomläggningen. Do it once, get it over with? https://en.wikipedia.org/wiki/Dagen_H https://en.wikipedia.org/wiki/Dagen_H
- irrational 7y agoWhat would the cost be to change everything for a country the size of the USA? I imagine it would be in the trillions.
- zamalek 7y agoThe situation is far more bizarre than "use" or "not use." As I understand it, America uses something along the lines of "converted metric units" - i.e. the entire imperial system is defined according to metric/SI. Some subset of public records have been, supposedly, converted to metric. If you have a recent car, it should have km/h alongside mph (in a smaller font, or as a different digital readout). You'll find metric all over the place if you keep an eye out for it.
- sbierwagen 7y agoUS cars have had dual speedometers for decades. One example: https://www.ebay.com/itm/NOS-1980-1981-FORD-MUSTANG-85MPH-SPEEDOMETER-ASY-/372373390303 https://www.ebay.com/itm/NOS-1980-1981-FORD-MUSTANG-85MPH-SP...
- moron4hire 7y agoIt's called "US Customary", not "imperial".
- Taniwha 7y agoOnly in the US - except for gallons/fluid ounces - those genuinely are US only
- moron4hire 7y agoNo, that's my point. The system of units that is used in the United States is not "Imperial", it has differences from Imperial. We use "US Customary".
- spritecranberry 7y ago> The situation is far more bizarre than "use" or "not use"... "converted metric units" You're absolutely right. It's time we removed the quasi-metric garbage and replaced it with proper customary units defined on the same universal constants used by SI units.
- deleted 7y ago[deleted]
- alexpotato 7y agoBack in the 90s, new construction for the US Govt was supposed to all be done using the metric standard even though all of the supplies were in US/Imperial units. Can't imagine the headaches that caused. Source: My uncle who is/was a contractor
- kevin_thibedeau 7y agoThe Comanche helicopter was subject to this dictum. The original drawings specified all metric fasteners. They found out nobody supplies aircraft grade metric bolts so everything had to be redesigned for the next size up in freedom-units with a corresponding weight penalty.
- analog31 7y agoWe are. All of the US standards are based on metric units. A large number of the products that we buy are made from metric components such as screws. CAD software and machine tools can switch effortlessly between unit standards. There are some standards that are so unique that they might as well be arbitrary, such as spark plug threads. Some building materials still have US dimensions, but if you measure plywood carefully, it's thicknessed in mm. And the "2 x 4" has never been 2 x 4 inches. So I think we've made great progress towards an age when units of measure don't matter much any more.
- big_chungus 7y ago> the "2 x 4" has never been 2 x 4 inches. Well, it used to be pretty close, until lumber manufacturers and builders cheaped out. They've been gradually "shrinkflating" by reducing the thickness, conveniently requiring less wood. This went along with the switch to fast-growing garbage pine. I lived for a long time in an early-fifties house, and the quality of the wood was vastly superior to what you'd find today. Though, the newer measurements did make things a pain.
- Taniwha 7y agoHere in NZ when we switched to metric nothing changed, 2x4s (well we call the 4x2s) were never quite 2x4, and 50x100s (the metric replacement) are close enough (but still not quite) that nothing really changed
- oivaksef 7y agofour buh two
- Jamwinner 7y agoNo the difference is that we process wood now. Look up dimensional lumber. Its confusing, but makes sense if looked at historically. Iy is not shrinkflation or any other such nonsense.
- beerandt 7y ago
- zokier 7y agoThey are using metric: https://geodesy.noaa.gov/INFO/Policy/files/SPCS2022-Policy.pdf https://geodesy.noaa.gov/INFO/Policy/files/SPCS2022-Policy.p... > The meter is the unit of the defining linear parameters for SPCS2022 > SPCS2022 coordinates are published in meters
- beerandt 7y ago83 was also defined in metric, but most states chose to use feet for their actual grid.
- opwieurposiu 7y agoAs an example of a problem that can occur: Client wants to survey the elevations of a parcel of land for building a house. The surveyor goes out and collects data with gps survey equipment, which produces a .csv file of northing,easting,and elevation values relative to some National Geodetic Survey benchmark. The engineer imports this .csv into his cad software, produces a grading plan .csv file. The earthmoving contractor imports the grading plan into his software and grades the site. Client gets house built, moves in and discovers that the front yard turns into a swamp after every rain. Somewhere in the chain of importing and exporting .csv files, software A was using survey feet and software B was using international feet. This can also cause problems like structures built in the wrong spot, fences built on neighbors land, etc.
- abofh 7y agoThe difference is .0002%. your examples would barely add up to an inch over a mile.
- opwieurposiu 7y agoSometimes the benchmark for northing/easting/elev is many miles away from the actual site. This is especially true with gps surveys. It only takes a few inches to wind up with a substantial drainage problem.
- function_seven 7y agoWouldn't the elevation difference between benchmark and site be the important bit here? If so, then the difference would rarely be more than a mile, and the resulting error would be at most an 1/8"
- beerandt 7y agoIt's that you're in the wrong e, n location, which may be at an entirely different elevation than where you want to be.
- 7y ago
- DoofusOfDeath 7y agoThe article left me confused about what it means to have a legally binding redefinition of a term. Does this mean that all existing, legally binding contracts are to be reinterpreted using the new definition of "foot"? Does it mean that any new legal document (contract, legislation, etc.) that uses the term "foot" without further clarification shall be assumed to mean this new definition of "foot"?
- ska 7y agoI believe it is the latter.
- not2b 7y agoIn practice, since the difference is so small it does not matter in almost all cases, because no one was in a position to measure accurately enough. If you ask for 100 feet of rope, the difference between the two definitions of "foot" is much tinier than the smallest possible roundoff error you or the sales person will make.
- ska 7y agoThat's fine for measuring most things, but not necessarily for survey work. Your reference points can be quite far away, and you are dealing with angles. So ever pretty tiny changes can be significant.
- oh_sigh 7y agoAs a general point, I don't think contracts can have their terms adjusted after the fact without both parties agreeing to it.
- ska 7y agoThis seems the only reasonable way to do it except for terms deemed unenforceable (which is why you see a lot of boilerplate about severability)
- ska 7y agoAh, the joy of standards.
- DeepYogurt 7y agoImagine it being 2020 and not using the metric system.
- 3fe9a03ccd14ca5 7y agoI don’t really mind that we’re not on the metric system. I just wish our measurements were consistent as they increase. E.g. foot, kilofoot, etc. instead of foot, yards, miles.
- thechao 7y agoAnd base-2, rather than the computer-unfriendly base-10. Aaaaactually ... with a bit of squinting the U. S. customary volume system(s) define a complete set of base-2 nouns (which could be used as prefixes): tbspn oz jill gill cup pint quart half gallon peck kenning bushel rundlet barrel hogshead butt tun Where each item below the next item is exactly 2x the previous one. It turns out there's also some base-3 stuff (for measuring simplicity), like the teaspoon, etc. I've always imagined we could redefine a few things to make a "completely rational" U.S. customary measure. That'd be: 1 in == 2.5 centimeters (as Thomas Jefferson wanted) 256 in^3 == 1 gallon (water at 32° F) 1 in is a bit awkwardly small. A cup-inch is ~1.3ft. A pint-inch is exactly .8125m. Luckily, a 'tun-tun-inch' (65536in) is 1.0343 miles, so we could define a a 'tun-tun-inch' to be a mile, etc., etc.
- madcaptenor 7y agoThat gives you a gallon of exactly 4 liters (256 * 2.5^3 = 4000 mL). Alternatively, a quart is now just another name for a liter.
- ranger207 7y agoFractional lengths in the US are commonly in base-2, ie, 1/2", 1/4", 1/8", 1/16", etc. Still annoying to remember that the next socket up from 1/2" is 9/16".
- 7y ago
- deleted 7y ago[deleted]
- Animats 7y agoFortunately, the inch is defined as 0.0254 meter exactly. So we have consistency for the really important units.
- AnimalMuppet 7y agoThen which "foot" is exactly 12.000000 inches?
- function_seven 7y agoThe International one (i.e. Non Survey Foot) > In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.3048 meter exactly. So 0.0254 * 12.000000 == 0.3048
- ansible 7y ago0.3048 meters / 12 = 0.254
- mark-r 7y agoMy calculation shows 12 * 0.0254 = 0.30479999999999996 meters. That may be off a little due to IEEE floating-point inaccuracy.
- d-sc 7y ago2 * 4 = 8 so the last significant digit should be an ‘8’
- jackfoxy 7y agoI knew about the survey foot because both the l00' tape measures I have are in survey feet. Messed me up on a home construction project about 13 years back. It was then I learned there are 2 differing feet definitions.
- function_seven 7y agoAre you sure it was the differing length of each version (about 610 nanometers), or was it because your tapes were marked in tenths of a foot instead of inches?
- jessaustin 7y agoI have actually worked with people who didn't notice this about their 100' tapes. Even better are the tapes divided by 12 on one side and 10 on the other...
- jackfoxy 7y agoWell this was a false memory I may now remember as false. No, it wasn't tenths. I think more likely it had to do with the claw at the start of the tape for attaching to your starting point, which does not stay at a rigid 90 degrees. My memory is that over several tens of feet I was off by 1/8 inch.
- dan-robertson 7y agoOver the length of a 100’ tape, the difference is about 61 um, ie 0.061 mm. How could that difference have any effect?
- alamortsubite 7y agoIf someone had told me this statement was part of a Monty Python script, I'd likely have believed them.
- drdeadringer 7y agoI don't see anything wrong with "truth in comedy". A part of me believes that's how comedy works: if it wasn't true you wouldn't be laughing, and another part of me is laughing because the same truth is sad.
- Infernal 7y agoFor those of us who came later to the discussion, what was the original title?
- alamortsubite 7y agoI was referring to the content of the post on nist.gov. But I think the title has changed, and may have been simply "U.S. Survey Foot" when I first commented.
- p1mrx 7y ago> In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.304 8 meter exactly. We can thank one man for this: Carl Edvard Johansson from Sweden. When making gauge blocks, he decided to round off the inch to exactly 25.4mm, and people around the world used his blocks to manufacture everything. The 1959 change just reflected what industry was already doing. - http://mitutoyo.com/wp-content/uploads/2013/07/E12016-History-of-The-Gage-Block.pdf#page=8 http://mitutoyo.com/wp-content/uploads/2013/07/E12016-Histor... - https://books.google.com/books?id=3rUaAQAAMAAJ&lpg=PA293&ots=hiqJuRiYSM&pg=PA293 https://books.google.com/books?id=3rUaAQAAMAAJ&lpg=PA293&ots...
- analog31 7y agoAn interesting factoid is that if you rummage around in a machine shop, you will find a pair of gears in a drawer somewhere, with 50 and 127 teeth. Those are for converting an old fashioned manual lathe to cut metric screw threads.
- Svip 7y agoJust FYI, a 'factoid' is something believed to be true, when it probably isn't. I assumed you meant 'fact', but otherwise your comment could be confusing.
- zamfi 7y agoThat is indeed one sense of the word factoid, but in common North American usage it also can mean “small or trivial piece of information”, which is the sense I believe the parent poster is using.
- beerandt 7y agoFor reference, a US survey foot is legally defined as 1200⁄3937 meters, which is ~0.304801 meters. The difference is usually written as 2ppm, for practical purposes. (To match units for survey equipment accuracy.)
- samatman 7y ago
- seancoleman 7y agoI actually learned of the difference between the U.S. Survey Foot and the International Foot while working on https://plantpredict.com https://plantpredict.com. For years we had infrequent but bizarre unit-conversion bugs. Calculations literally weren't adding up. We assumed it was related to precision rounding since numeric input fields showed rounded values. It turns out the imperial-to-metric feet conversion factor we picked was 1 of 2 choices, and we picked wrong!
- alleycat5000 7y agoA good overview on NSRS can be found below, pretty interesting read if you're into datums. https://www.esri.com/about/newsroom/arcuser/moving-from-static-spatial-reference-systems-in-2022/ https://www.esri.com/about/newsroom/arcuser/moving-from-stat...
- jessaustin 7y agoThank you 'amjaeger for removing the local-TV-news-level attempted pun from the headline.