I think we should tag what's on the signs ie. mph, as a conversion to kmh is error prone even without the rounding issues. I've tagged my local roads as maxspeed=20mph|30mph|etc....
Any application parsing maxspeed values needs to validate the data anyway because like all our data the field could contain anything so checking for mph as a suffix is hardly a big deal. Kevin On Thu, Jun 4, 2009 at 8:45 AM, Peter Miller <peter.mil...@itoworld.com>wrote: > > I have been looking at the coverage of maxspeed limit data for highways in > the UK and we seem to have a right mix of styles. > > Here is the data for bug chunk of England while avoiding including anything > from France or Ireland (which would include km/hour figure). We current > have over 17,000 highway ways tagged with maxspeed and also 300 ways tagged > as 'maxspeed:mph'. You will notice that for 30 miles per hour we have 30, > 30mph, 30 mph, 48.2, 48.28, 48.280, 48.27808, 48.28032 and 48.28. > > Any suggestion on what we should recommend for the UK? I guess the USA > should also be party to this discussion but they have far less population of > the maxspeed field (only 70 uses in the Bay area) so possibly we should come > to a view first. Our options seem to be:- > maxspeed=30mph (the user should strip a trailing mph to find the value) > maxspeed=30 (leaving it for the user to realise that it is in the UK and > therefore imperial) > maxspeed=30 mph (the user should strip the last word if it is mph including > the space) > maxspeed:mph=30 (Easy for the user) > maxspeed=48.28 (with a defined precision) For metric use no work by the > user, for imperial use a look-up table is required or a conversion and > rounding > > > Here is what we have at the moment for 'Mid England' including London, > Portsmouth, Bristol, B'ham up to Liverpool, Manchester and Leeds etc) > starting with the most popular:- > > 30mph 5185 > 48.0000000 4155 > 20mph 1282 > 64.0000000 922 > 32.0000000 871 > 40mph 833 > 96.0000000 383 > 30.0000000 341 > 80.0000000 300 > 112.0000000 294 > 30 mph 263 > 60mph 245 > 50mph 244 > 50.0000000 164 > 20 mph 160 > 48.2803200 144 > 48.2800000 97 > 40 mph 95 > 48.2780800 75 > 24.0000000 69 > 64.3700000 67 > 16.0000000 67 > 60.0000000 60 > 113.0000000 58 > 40.0000000 54 > 100.0000000 43 > 8.0000000 41 > 50 mph 40 > 97.0000000 39 > national 35 > 80.4672000 32 > 20.0000000 31 > 64.3737600 29 > 70mph 27 > 10 mph 23 > 5mph 20 > 10.0000000 20 > 10mph 18 > 70 mph 18 > 5 mph 15 > 15mph 14 > 110.0000000 11 > 80.5000000 11 > 32.1800000 10 > nsl 9 > 36.0000000 9 > 60 mph 8 > 45.0000000 6 > 15.0000000 6 > NSL 6 > 32.1868800 6 > 19.0000000 5 > 7.0000000 5 > 64.4000000 4 > 11.2000000 3 > 42.0000000 3 > 15 mph 3 > 5.0000000 3 > 48.2800000 3 > 12.8000000 2 > 70.0000000 2 > 96.5606400 2 > 160.0000000 2 > 30mph..change me! 1 > 80; 50mph; 80 1 > 32.1870000 1 > Carr Lane 1 > 112.6540800 1 > 38.0000000 1 > 48;96 1 > 32.2000000 1 > 48;64;80 1 > 8.0500000 1 > 54.4000000 1 > 48.3000000 1 > 48.2000000 1 > 16.0900000 1 > 12.0000000 1 > > Regards, > > > Peter > > > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-gb > >
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