On Thu, 30 Jul 2009 08:43:22 +0000 (GMT), John Smith <delta_foxt...@yahoo.com> wrote: > --- On Thu, 30/7/09, Aun Johnsen (via Webmail) <skipp...@gimnechiske.org> > wrote: > >> much more. Since many countries have two different signs >> for max legal >> height and max physical height, and its usages can be very >> different, why >> not allow this in tags? > > So why not just use maxheight=* and maxheight:legal=* ? > >> By saying that there is no difference between maxheight and >> clearance is >> for me the same as saying there is no difference between >> highway and >> cycleway, tourism and historic. > > I fail to see the difference, most maxheight matches the clearance to > within 15cm, maxheight is a restriction tag and clearence would be a > restriction tag stating the same with a second name. > > There is however a big difference with highway and cycleway, both physical > and legally, there is usually very little difference between legal and > physical clearance. > > You also mentioned sailboats under bridges, are you planning to update the > clearance 24 hours a day, 7 days a week as the tide goes in and out? You are clearly not familiar with the term "free sailing height" which refers to the height from mean sealevel (used in marine charts), up to a portion of the bridge span which os over the safe channel. This value is stated in all marine charts as a reference to any ships captain for him to verify that his vessel can pass safely under the bridge with his current air draft. There is no need to correct this more often than the bridge is reconstructed as you will correct this value towards tidal information available for the closest port. -- Brgds Aun Johnsen via Webmail
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