I think we would always use the decimal in the US, its common practice and well understood both in measurement (metric or English) and other (i.e. finance). If you posed clearance as 4 2 meters vs. 4.2 it is likely drivers would think you meant 42 meters. Especially during that multi year period when people are getting used to the feel of the metric system. By way of clarification: I was not suggesting that 4 2 meters was a good way to do it, just that if in fact "4.2 meters" was used, but the decimal became blotted out, 4 2 meters would still be understood as 4.2 meters, given that you are driving up to a bridge that was about twice as high as your vehicle. I have read objections to the use of decimals as causing confusion (if not seen), and for that reason (not wanting to risk "4.2 meters" being misunderstood), that decimals shouldn't be used. I actually would prefer to see 4.2 meters to anything else, and especially, prefer it to 4 2 meters. Hopefully I haven't mucked that issue up too much. :) Additionally, the issue about the decimal wasn't simply whether to write it out (4.2 vs 4 2), but about what unit to use. If there aren't going to be any decimals, a bridge clearance would have to be expressed in decimeters, centimeters, or millimeters. As you're doubtless aware, the first isn't a common unit, and the other two would give very large numbers, so I was wondering how the "no decimal" rule would apply. But I'm glad to see folks open to the use of decimals.
From: [email protected] To: [email protected] Date: Thu, 2 Feb 2012 09:09:58 -0500 Subject: [USMA:51435] RE: Standard unit for driving clearance I believe that bridge clearance is marked 1’ below actual unless it is below the minimum 14’ (16’ on most interstates) in which case we sometimes put up a sign with the clearance and words “actual”, for example we might say Clearance 13’ 2” actual. I would assume if we ever go metric on signs we would use 0.3 m below actual for the posted clearance in meters. Since no highway agency in the us actively places metric signs many of the rules are not yet written or well defined. From: [email protected] [mailto:[email protected]] On Behalf Of John M. Steele Sent: Wednesday, February 01, 2012 4:11 PM To: U.S. Metric Association Subject: [USMA:51434] RE: Standard unit for driving clearance Looking in SHS (Standard Highways Signs) which provides dimensional detail for the signs in MUTCD, I'm of the opinion that the period, single and double quote in the standard sign alphabet are larger and heavier than in most computer fonts. I can find the specs in SHS, but not for computer fonts like Arial. If I print them large, the SHS special characters look heavier and more prominent. Plus per MUTCD, one decimal is ALWAYS used. 2 m would be 2.0 m. It is significant as it shows the precision to which the measurement is stated (greater than or equal 2.0, less than 2.1) I would have to disagree with any metric literature that says NEVER use decimals. Why bother to have a decimal system if you can't use decimals? It would be good practice to change the prefix to generally avoid numbers less than one, ie only decimal, and if you can't avoid it, a leading zero is mandatory, but no decimals is like saying prices must be integer dollars. --- On Wed, 2/1/12, Paul Rittman <[email protected]> wrote: From: Paul Rittman <[email protected]> Subject: RE: [USMA:51432] Standard unit for driving clearance To: [email protected] Date: Wednesday, February 1, 2012, 3:06 PM2.2 m looks easy enough. I personally don't recall ever having problems with the inch symbol (")--either being rubbed out or mistaking it--so I don't see why 2.2m is a bad way to express it. But I know I've read metric literature that say that you shouldn't ever use decimals. Even if the point were rubbed out, I think 2 2 m would be clear enough for a bridge that is almost scraping the roof of the car. Maybe I'll start another topic on decimals, if it hasn't been beaten to death yet. :) Date: Wed, 1 Feb 2012 11:05:43 -0800 From: [email protected] Subject: Re: [USMA:51432] Standard unit for driving clearance To: [email protected]; [email protected] UK and the US both round down to lower whole decimeter, but express it as meters with a tenth digit, ie 2.2 m. Actually, the UK rounds down, then subtracts another 0.1 m so your example would be 2.1 m in the UK, 2.2 m in the US. I think Canada would be the same as US but i've never found the printed rule. For the US, the MUTCD would not regulate marking in a private parking garage so you might find a "bad" conversion from feet and inches. --- On Wed, 2/1/12, Paul Rittman <[email protected]> wrote: From: Paul Rittman <[email protected]> Subject: [USMA:51432] Standard unit for driving clearance To: "U.S. Metric Association" <[email protected]> Date: Wednesday, February 1, 2012, 1:27 PMOccasionally I read of people complaining that they saw a sign that said that the clearance for a bridge was 2257mm or something like that. I realize that if you gave the figure in meters, you'd need to use the decimal for measuring the clearance of a bridge, or the lower level of a parking garage, etc. Is there a standard unit that is given for occasions like this?
