AARoads Forum

I suppose I could have posted this in the general highways board, since this applies to highways, but I wanted to make this thread a bit more general.

Basically, do you think the U.S. (or if you're not American, you may substitute your country in this question if you like) should use the metric/S.I. system, or the traditional/English system of units? E.g. do you prefer meters or feet, liters or gallons, kilograms or pounds?

Being Dutch, I never learned anything but the metric system.

However, I understand some measurement of the imperial system, mostly gallons, inches, fahrenheit, feet, miles, but not square feet or square miles, not to mention cubic feet / cubic miles.

Chris: if you want to understand square miles, pull up Goldsby, Oklahoma on a map. That's where I grew up, and grokking square miles is easy because each of the "major" paved streets are 1 mile apart. Thus each square formed by the street grid is 1 square mile.

I do think we should switch over, being that's the units the rest of the world uses and we're kinda at a disadvantage not being able to understand them. Plus they seem easier to use. But learning them might take a while.

Quote from: Chris on October 01, 2009, 04:07:39 AM
Being Dutch, I never learned anything but the metric system.

However, I understand some measurement of the imperial system, mostly gallons, inches, fahrenheit, feet, miles, but not square feet or square miles, not to mention cubic feet / cubic miles.

I think that sums up how much anyone knows of the imperial system.  I think that the US should switch to metric, but I do have issues with a couple of the metric measurements:
-Kilometers: the fact that they are so much shorter than miles makes them an inferior method with regard to roads.  Just go to Canada to see what I mean; signage for exits is almost twice as close to the exit as US signage is.  They can't even fit service signs in, they have to be posted before the advance signage (but this is VERY useful for taking sign photos as it gives advance warning for the guide sign).
-Celsius: I know it is better for telling is you are above/below the freezing point, but Fahrenheit has double the precision.  Simply using 200 for boiling instead of 100 would fix this.

Interestingly, some New England states have dual imperial/metric distances on exit signs.

Quote from: deanej on October 01, 2009, 01:32:13 PM

-Kilometers: the fact that they are so much shorter than miles makes them an inferior method with regard to roads.  Just go to Canada to see what I mean; signage for exits is almost twice as close to the exit as US signage is. 

I don't need to go to Canada for that.  :colorful:

In Europe, signage regarding exits is different per country, Germany, for instance, uses 1000 m - 500 m intervals, while the Netherlands uses 1200 m - 600 m intervals, and Poland begins as early as 3000 m in advance. I don't think signage for exits is necessarily a thing related to kilometers, but more a Canadian thing. (I don't know which intervals Canada use though).

Logically, I think we should go to the metric system.

But, emotionally, the imperial system is what I learned and understand.

I have a good idea in my head if someone say something is 10 miles away but if they say 16km (approx the same distance), I have to convert it to miles in my head to get an idea of it.  Of course, if I had grown up learning only the metric system, I'm sure I'd be used to it.  There will always be some resistance from older folks if we try again.

Back in the early-mid 70s when I was in grade school and middle school, the U.S. made the biggest push that I remember to go over to the metric system, but it fizzled out.

IMHO The main reason that we've been able to get away with not changing has been that we've been the top dog or one of the top dogs in the world.  If current trends continue and some other country takes over as the leading power (i.e. China), then we will probably be forced to change over.

I just replied "no" because I like the Simpsons quotes.  But in reality, I mean "yes."  I learned some metric growing up but I haven't internalized it.  Rarely, I refer to things in meters/centimeters when they seem like a handier unit.  I do not use liters or cL or mL with any regularity, and grams not much more than that.  We have a long way to go, but we have to stop being stubborn and just go and do it.  Kinda like how Sweden switched sides of the road overnight.

Quote from: deanej on October 01, 2009, 01:32:13 PM
Just go to Canada to see what I mean; signage for exits is almost twice as close to the exit as US signage is.  They can't even fit service signs in, they have to be posted before the advance signage (but this is VERY useful for taking sign photos as it gives advance warning for the guide sign).

I don't know if that's universally true. In greater Vancouver, the exits are signed well ahead of time (usually at 1600m, 800m, 400m or thereabouts--which is incidentally about 1 mile, 1/2 mile, 1/4 mile). Plus, if you want better signage, use metric and just adjust accordingly.

Quote from: deanej on October 01, 2009, 01:32:13 PM
-Celsius: I know it is better for telling is you are above/below the freezing point, but Fahrenheit has double the precision.  Simply using 200 for boiling instead of 100 would fix this.

Fractions a problem? Incidentally, Fahrenheit was, I believe, originally set up to have a zero point at the freezing point of the much more prevalent salt water in some part of the ocean. The problem with that is that the salinity can vary and have a significant effect on the freezing point. Also, using 200 would not fix this--you'd have to get the scientific community to switch their units too, to really accomplish anything. Good luck with that.

Am I the only one that doesn't care?

Honestly, if we switch to metric, sure, it will be a challenge at first to learn, but I can get used to it. Heck, New Hampshire and the Maine Turnpike use bilingual distances.

My $0.02
Ian

One HUGE advantage that the USA will realize once things are pretty much all 'SI' is that we will no longer have to torture our grade schoolers with having to learn fractions in math.  We eliminated one of the two major reasons for fractions about ten years or so ago when the USA went from binary fractions of dollars to decimal dollars and cents in prices quoted in stock and commodities markets - and would ANYONE ever want to go back on that now?  Pretty much everywhere else in the World, students don't encounter fractions until advanced high-school algebra and not teaching them in grade school will cut well over a year, maybe as much as two years, off of the time that it takes to teach them basic math.

And yes, my mind wants to know how many degrees above or below freezing it is and Celsius gives me that straight out.  An aside - I recall many years ago, in a first grade class where we were being introduced to measures, the teacher asked 'What temperature does water freeze at?'.  I meekly raised my hand and, not really knowing much at all on the subject, said 'Zero?'.  After a strange stare in response, she then asked 'What temperature does water boil at?'.  Again, I meekly raised my hand and said 'One hundred?'.
I ask, if it was *THAT EASY* for me to figure out back then, how on earth can it be hard for anyone else to figure out Celsius temperatures now???

Mike

Metric. Km/h and Celsius are easier for me to understand. Spending a lot of time in Canada growing up helped with that.

I must admit, cm and mm are rather handy measurements, and in fact I can picture a cm (and an mm) in my head much more readily than an inch. And I don't have to sit there and stare at the ruler going "okay, I know that long line is 1/2 inch...so that one that's a bit shorter is 1/4...which means that's 1/8... so this thing I'm measuring is... 5/16? Shit."

Quote from: mgk920 on October 02, 2009, 12:02:15 AM
One HUGE advantage that the USA will realize once things are pretty much all 'SI' is that we will no longer have to torture our grade schoolers with having to learn fractions in math.  We eliminated one of the two major reasons for fractions about ten years or so ago when the USA went from binary fractions of dollars to decimal dollars and cents in prices quoted in stock and commodities markets - and would ANYONE ever want to go back on that now?  Pretty much everywhere else in the World, students don't encounter fractions until advanced high-school algebra and not teaching them in grade school will cut well over a year, maybe as much as two years, off of the time that it takes to teach them basic math.

And yes, my mind wants to know how many degrees above or below freezing it is and Celsius gives me that straight out.  An aside - I recall many years ago, in a first grade class where we were being introduced to measures, the teacher asked 'What temperature does water freeze at?'.  I meekly raised my hand and, not really knowing much at all on the subject, said 'Zero?'.  After a strange stare in response, she then asked 'What temperature does water boil at?'.  Again, I meekly raised my hand and said 'One hundred?'.
I ask, if it was *THAT EASY* for me to figure out back then, how on earth can it be hard for anyone else to figure out Celsius temperatures now???

Mike

Eh, kids should learn fractions regardless of whether they're necessary for reading a ruler.

Since I never stated my position on SI vs. English units in my first post, I'll just say that personally I'm in favor of using SI instead of English. I work in a field that (in theory) entirely uses metric units, though if you try to submit a job to the machine shop dimensioned in millimeters, you can expect to have it rejected with a comment telling you to convert it to inches...

Metric.
How many feet are in a mile? 'nuff said.

Quote from: Bickendan on October 03, 2009, 03:24:02 AM
Metric.
How many feet are in a mile? 'nuff said.

never mind that, how many grams in an ounce?  Okay, 28.35 sounds reasonable, if difficult to count on one's finger.  Except when measuring gold, when it's 31.10 grams to the Troy ounce.

same with miles: at sea, they're longer.

the insidiousness of the Old English system goes a lot deeper than just having wacky conversions.

Quote from: mgk920 on October 02, 2009, 12:02:15 AM
One HUGE advantage that the USA will realize once things are pretty much all 'SI' is that we will no longer have to torture our grade schoolers with having to learn fractions in math.

fractions are not torture.  Madame Bovary is torture, and Catcher in the Rye is at the very least malicious wounding.

Quote from: Bickendan on October 03, 2009, 03:24:02 AM
Metric.
How many feet are in a mile? 'nuff said.

That's easy... 5,280 feet = 1 mile  :sombrero:

Besides if we convert to metric Denver would no longer be known as the "Mile High City", it will have to be known as the "1.609-Kilometer High City"  :confused:

Seriously though, I would just prefer we leave things in the U.S. just as they are.  When I hear a basketball player is 7 feet tall, I know that's a tall guy.  "2.133" meters doesn't have the same impact as "7 footer".  When I hear it's going to be 100 degrees outside I know that it's going to be really hot.  Once again, 37.8 doesn't carry the same emphasis as 100.  Yeah metric is easier to calculate with everything being Base-10 but that doesn't mean I have to like it.  Finally, if all you metric supporters are willing to pay higher taxes (income, gas, sales... whatever) to convert every single freeway sign to metric, kudos to you because if you expect the government to foot the bill for a possible conversion to metric, then I gotta bridge I want to sell to you...

My answer to how many feet are in a mile is: who cares?  In the very, very rare instance I actually need to convert units, that's what the unit converters on both my phone and graphing calculator are for.

The cost of converting would vary state by state.  In NH there would be none, as they already use dual imperial/metric.  The Maine Turnpike would have some cost due to the exit numbers.

And now for some facts on Fahrenheit:
-0 was the lowest temperature usually seen each year in Europe
-100 was the highest
-The guy who invented the scale lived in the far north where the temperature never rose above the freezing point, so the water freezing at 32 thing was not a consideration.
-There was an even older system where water froze at 6.7 (0 was the freezing point of water mixed with salt)

1km = 1000 meter. 1m = 100 cm. 1cm = 10 mm

1 mile = 5,280 feet. 1 feet = 12 inch. 1 inch = ?

you get the idea  :sombrero:

Seeing as I use metric measurements all the time (after all, I am a pharmacy technician), I really have no problem with them, and they didn't seem hard to learn. I have a few conversions committed to memory: 30mL = 1oz, 2.2kg = 1lb, 2.54cm = 1in, etc.

I'm too lazy to convert to the metric system (imagine if they did  :ded:) so I'll stick to the miles. Besides, the metric system is used in almost ALL the countries, so ours is somewhat unique  :colorful:.

"Mile" does have a ring to it that "kilometer" doesn't. Major turning points are called "milestones", not "kilometerstones", after all...

Quote from: Scott5114 on October 03, 2009, 09:56:45 PMMajor turning points are called "milestones", not "kilometerstones", after all...

:-P

Quote from: Scott5114 on October 03, 2009, 09:56:45 PM
"Mile" does have a ring to it that "kilometer" doesn't. Major turning points are called "milestones", not "kilometerstones", after all...

That's true. Even in Dutch, we say "mijlpaal" (mile marker) for a significant accomplishment.

After all, I do think the imperial system has it's charm. I can't imagine hearing kilometers in American movies for instance.

I'm not sure if converting to metric justifies the cost. Just like the UK is never gonna change the driving sides...

I have always thought that the biggest hangup on 'just doing it' with completing the conversion has been that the 'Olde Englische' units' names are just so damn poetic to say out loud.  :rolleyes:  Never mind that many/most of them have little real commonality with the others as one goes from one scale to another.

Also, the USA showed beyond a doubt that the 'cost of changing the signs' argument is nothing more than a red herring - look how truly *FAST* some states hopped to it to their change speed limit signs when the NMSL repeal took effect back on 1995-12-08.  They had overlay stickers all lined up and distributed and the crews ready to go within minutes of the zero time.

:-o

Mike

We're not French.

I just assume wait for some American scientist to develop a system of measurement better than the metric system, then we can adopt that. In the meantime, I'll be sticking to Imperial Units until the day I die

Quote from: mgk920 on October 04, 2009, 03:39:57 PMlook how truly *FAST* some states hopped to it to their change speed limit signs when the NMSL repeal took effect back on 1995-12-08.  They had overlay stickers all lined up and distributed and the crews ready to go within minutes of the zero time.

that's because the states welcomed the repeal of that dang NMSL.  Everyone knew the highways were designed for 70-80mph, people were going 70-80mph, and to set a speed limit that was not in line with that (the 85% rule) was viewed as unnecessary federal meddling.  Civil wars were started for less!

Quote from: corco on October 04, 2009, 03:51:38 PM
We're not French.

I just assume wait for some American scientist to develop a system of measurement better than the metric system, then we can adopt that. In the meantime, I'll be sticking to Imperial Units until the day I die

in what possible way can a system of measurements be better than metric?  Maybe less dorky-sounding names, and a mass reference that is less small?  But the idea of base 10 calculating, consistent prefixes, etc, are generally the end of the line as far as this idea goes.  It's like asking to invent a better wheel.  

(converting humanity over to base 12 to facilitate dividing by 3 and 4 is an entirely different topic!)

I suppose I might be down with it if we simply used Imperial names with the SI units- so an SI kilometer would henceforth be known as a mile, a meter as a yard, a kilogram as a pound, a centimeter as an inch, etc. Units with no logical counterpart could continue to be known by their SI names.

That might just confuse everyone, though.

Or yeah, just better sounding names, preferably after former presidents. I propose:

1 km becomes 1 Washington
1 m becomes 1 Jefferson
1 kg becomes 1 Reagan
1 cm becomes 1 Adams
1 mm becomes 1 Lincoln
 
and so on and so forth.

If you structured it more carefully, you could help kids learn Presidential history while teaching them measurements! That's how we get ahead, folks

no no no, dead politicans already have enough named after them!  Maybe scientists, but the SI system already includes them: Curie, Ampere, Tesla, etc.

besides, if you're going to include Reagan, you'd have to include Kennedy ... and one, if not both, of those will make most people shudder!

The intent would be to include all presidents arranged in such a way that it would help small children memorize the presidents in order (so, not the way I started to do it above)

Quote from: corco on October 04, 2009, 04:25:11 PMmemorize the presidents in order

that does not sound like a very useful undertaking.  children would remember the presidents more naturally if their accomplishments were mentioned, and not just their names.  Washington deserves to be remembered not just because he's the guy on the dollar bill, but because of what he achieved, which can be learned about as part of the curriculum.  Harding deserves to remembered for ... well, lemme get back to you on this one.

I remember being forced to memorize the state capitals - once I was done being tested, I promptly forgot.  To this day I remember Philadelphia being the place where the Declaration of Independence was signed, Ben Franklin's home city, etc etc... I really have to struggle to remember what the capital of Pennsylvania actually is, and frankly not very many people outside the state really have an overwhelming need to know. 

and if they do, there's always google.  We mercifully no longer live in an age of memorization.

In that case I am in favor of renaming SI units for counties in Texas. It would appease the rednecks.

Also, memorization is still very, very important. I'm convinced America is becoming stupider because we have access to an internet. It's good for our brains to be forced to remember stuff.

Quote from: corco on October 04, 2009, 04:49:47 PM
Also, memorization is still very, very important. I'm convinced America is becoming stupider because we have access to an internet. It's good for our brains to be forced to remember stuff.

not memorization of trivial historical details, like names and dates and whatnot.  History is not to be regurgitated, it is to be analyzed using entirely different parts of the brain.  Columbus would be just as important if he did his thing in 1491 or 1493.

if we're going to remember stuff, let's remember useful stuff, like how to make fire out of commonly found items in the forest.

Quote from: corco on October 04, 2009, 04:49:47 PM
appease the rednecks.

haven't we done enough of that as a country? 

Quote from: corco on October 04, 2009, 04:49:47 PM
America is becoming stupider because we have access to an internet.

well, no one ever said 4chan was the intellectual capital of cyberspace ...

Quote from: agentsteel53 on October 04, 2009, 04:53:58 PM

Quote from: corco on October 04, 2009, 04:49:47 PM
In that case I am in favor of renaming SI units for counties in Texas. It would appease the rednecks.

haven't we done enough of that as a country? 

Oh, come on, Jake. You know you'd love it if distance signage was posted in glasscocks.

Quote from: Scott5114 on October 05, 2009, 05:39:09 AM
Oh, come on, Jake. You know you'd love it if distance signage was posted in glasscocks.

a glasscock is definitely a unit of volume.

SERIOUSLY: We're getting off topic.

Anyways, Subway has the five dollar footlong, not the five dollar .3048-meterlong ( :-P)

Quote from: Chris petite on October 05, 2009, 03:20:57 PM
SERIOUSLY: We're getting off topic.

Anyways, Subway has the five dollar footlong, not the five dollar .3048-meterlong ( :-P)

Yes, but for $16.40 you can have the meter-long!

 :-P :-P :-P :-P :-P :-P

I prefer that the U.S. stay on the English System.  However, I don't mind showing some things in both English + Metric measurements, such as speedometers, speed limit and mileage signs, and temperatures, wind speeds, snowfall, and barometer readings.  BTW, when I visit Canada, the barometer readings are given in kilopascals.  I would think since the U.S. gives them in inches, you'd think the metric unit to be used would be in centimeters.  Would any Canadians here be kind enough to explain why this is?  Thank you. :coffee: 

[Edited to expand arcane abbreviations. -S.]

The Pascal is actually a unit of pressure.  The inch is not.  This wouldn't be the only example of when Imperial and metric units aren't actually equivalent but are used as such; the pound is a unit of weight, not mass (the Imperial equivalent of the kg is actually the slug).

Quote from: deanej on October 05, 2009, 09:08:04 PM
The Pascal is actually a unit of pressure.  The inch is not.  This wouldn't be the only example of when Imperial and metric units aren't actually equivalent but are used as such; the pound is a unit of weight, not mass (the Imperial equivalent of the kg is actually the slug).

Eh, you're sort of nitpicking there. By your definition, the torr isn't a unit of pressure, either, since it's defined as the pressure change that causes a column of mercury to raise by one millimeter, similar to the definition of the inch of mercury.

Quote from: Tom on October 05, 2009, 05:14:27 PM
I prefer that the U.S. stay on the English System.  However, I don't mind showing some things in both English + Metric measurements, such as speedometers, speed limit + mileage signs, and temperatures, wind speeds, snowfall, + barometer readings.  BTW, when I visit Canada, the barometer readings are given in kilopascals.  I would think since the U.S. gives them in inches, you'd think the metric unit to be used would be in centimeters.  Would any Canadians here be kind enough to explain why this is?  Thank you. :coffee: 

First of all, "to" and "be" are really no harder to type than "2" and "b".  Second of all, it's because we measure in inches of mercury, which is a measurement in a thermometer.  Those inches are indirectly measuring pressure, which is in units of psi (pounds per square inch) or atmospheres (1 atm is the pressure at sea level, or 760 mm Hg - I don't know what that is in inches of Hg but it's something like 30.)

Technically everything except length, mass, and time are derived units.  My point was probably better served with the kg/slug example.

Quote from: deanej on October 06, 2009, 05:33:50 PM
Technically everything except length, mass, and time are derived units.  My point was probably better served with the kg/slug example.

isn't charge also fundamental?  Or can that be derived from the other three using some obscure quantum physics?

Oh yeah.  Sorry, was only thinking of newtonian mechanics there!

if they build the freeway link between the gravitational and electroweak forces like they've been planning to for the last N years, won't that make mass and charge interchangeable too?

dang NIMBYs preventing particle physics from moving forward!

Big metric fan here.  Of course, being in engineering, it'd be easier doing calculations if we used metric across the board. :p

Speaking of metric, I saw some Everett Turnpike photos from New Hampshire from earlier this year showing advance exit signs in both miles & kilometers.  These signs looked like they weren't too old, but I'm wondering if these were erected at a previous time, and are just waiting to be replaced with signs showing only miles.  I was curious if anyone had background on these signs.

Quote from: DanTheMan414 on October 06, 2009, 05:51:57 PM
Big metric fan here.  Of course, being in engineering, it'd be easier doing calculations if we used metric across the board.

Same here, although I know how stupid the average American is so I know they would not want to switch to that damned socialist measurement system.  I would be fine keeping the current units although I wish in our system, mass would be easier to figure out (it's always kilograms in metric but when we use it here, it's weight and you have to divide the weight by 32.174 ft/s^2 to get actual mass).

Quote from: Mr. Matté on October 06, 2009, 09:34:56 PM

Same here, although I know how stupid the average American is so I know they would not want to switch to that damned socialist measurement system.  I would be fine keeping the current units although I wish in our system, mass would be easier to figure out (it's always kilograms in metric but when we use it here, it's weight and you have to divide the weight by 32.174 ft/s^2 to get actual mass).

I tend to remain under generally constant gravity, so I'm okay with using a unit of weight ;)

For ordinary people, weight and mass would be interchangeable.  Most people don't even know the difference (or that the kg and lbs aren't actually equivalent units).

Quote from: deanej on October 06, 2009, 09:53:44 PM
For ordinary people, weight and mass would be interchangeable.  Most people don't even know the difference (or that the kg and lbs aren't actually equivalent units).

and non-ordinary people use metric approximately 100% of the time!  :-D

(in my physics class, we noted that it is actually correct to say that "on the moon, Neil Armstrong weighed 30 pounds" - and then we did the actual rocket science in metric!)

To clarify something which confuses a lot of people:

The US does not, and never has, used the Imperial system of measures. What we use was formerly known as and is often still called "English Units", but is now properly known as "US Customary Units".

The major difference is the definition of the gallon. One US gallon is exactly 231 cubic inches (just because that's a nice round number). One Imperial Gallon is the volume occupied by 10 (avoirdupois) pounds of water under standard conditions. The difference is not exactly but very nearly a 6:5 ratio (that is, 6 US gallons = 5 imperial gallons). Of course this also means quarts, pints, cups, etc. differ, too.
It also means that when someone from Europe reports a value in gallons (I see this a lot discussing fuel economy and MPG), often it will be in imperial gallons... and most people won't be aware that there's a difference.


True, the US customary measures aren't exactly intuitive.
3 teaspoons in a tablespoon, 2 tablespoons in a fluid ounce, 8 ounces in a cup, 2 cups in a pint, 2 pints in a quart, 4 quarts in a gallon... number of gallons in a barrel depends on what it's a barrel of (for crude oil, it's 55).
And if you think that's bad, look at your typical measurements of reservoir/lake capacity. Likely reported in acre-feet (1 acre-foot = 43560 cubic feet, same as the number of square feet in an acre).
Metric, which uses nothing but multiple of 10 (well, ideally, multiples of 1000; use of centi-, deci-, deka-, and hecto- is frowned upon in scientific applications) is most certainly simpler.

My key issue with using "metric" is that no country has actually yet done it properly. Post your speed limits in meters per second and record the temperature in Kelvins and then we'll talk.

Metric doesn't mean that you have to use SI units.

given it would cost mega-bucks in terms of re-education, changing machines, signage, labelling and so on and so forth, I reckon that the economic benefits would almost be cancelled out.

In the US, I suspect more people know the customary units, rather than the metric ones (especially when it comes to estimation - a unit that has evolved to be the right size for the job it's for is better than a completely artificial and arbitrary one for remembering and guessing how big it is).

We have these discussions rather often in the UK, where almost everything is officially in metric (even if pseudo-imperial). I think the best response I've heard is "If metric is so much better, how come imperial units have to be suppressed by law for people to not use them instead". People in the UK are varied - some can't use imperial, whereas others can use both systems but use a variety of different units or just one set, and finally there are people who can't use metric.

Given that I was schooled, almost entirely, in metric, the indoctrination failed: heights and weights of people need to be in feet and inches or pounds and stone for me to make sense of them - I convert cm/kg to the imperial units roughly in my head so I can get more manageable numbers - we can't easily visualise numbers more than 12 - perhaps 20 at a push - if we used decimetres and 10^4g (KILOgram being the base unit is very strange) - you could call such a thing as a myriagram, but no one would have a clue what that means - then the numbers would be better, but no one does. I can use metric for these things, but I'm much more comfortable in imperial.

I use a hybrid of units - metric for science, engineering, (maths is easier) and stuff which I'm unable to visualise anyway (very big, very small). Stuff on a more human scale uses imperial. I'm easy whether miles or km are used - they are in a no mans land.

As for the crazy irregular multiples, you don't use more than one of them at a time, and that's in the rare case of you using more than one unit - human height is one of the few, rare, exceptions (and human weight in the UK, where we make the 1stone = 14lbs conversion, so as to get more human numbers - under 20).

Also, I've got to love the pseudo- or neo-customary measures: light years, AUs, ångströms, plank lengths, electron charges, earth radii, kiloWatt-hours. Even hard-core metric fields like physics, energy generation, chemistry and so on aren't fully metric - whatever country you are in. Metric time was tried by revolutionary France and was rejected as a step too far, so we use things like days, weeks, years, hours, minutes (none of which are SI, and have varying conversion rates - just like all other customary units, though we even use several different units at the same time and have no problem - look at my post in a few days, and there'll be an example of it at the top of my post).

One advantage of the majority of the world switching to the metric system is that there is less ambiguity in units when there are fewer customary unit systems. Before the advent of the metric system, there was little to no standardization in units, so a "foot" was different in different places. Of course, now that there are only two systems remaining, most of the ambiguity is gone; an inch is 25.4 millimeters, as only one definition of the inch remains in common use.