Re: [OSM-talk] [talk-au] maxheight/height
Liz wrote: On Tue, 28 Jul 2009, Roy Wallace wrote: My main point is that when there is a maximum height under a way, this should be tagged as an attribute of that way, not of the ways that pass under it. Here I cannot agree When I travel over the bridge I am not interested in the maximum height of the way which travels under the bridge. When I travel under the bridge I am interested in the height limitation. Going back to my multipart specification, trying to really comprehend the logic the height of the arch is a property of the bridge. the max height which can go under the bridge is a property of the way / node beneath it note that counter-intuitively, height max height clearance May I just observe that when you go along a road, you will see 'maxheight' notices when you *enter* that road, frequently. This means an overheight vehicle cannot use that road. It can't use all except the little bit with the restriction. Therefore maxheight is a property of the way going under the bridge, possibly 1 way if the road is fragmented in OSM, and ought to be on the whole road from where the sign is until after the bridge. Also, although the sign may be physically attached to the bridge, it is placed to be visible to traffic on the way crossing beneath it, not to traffic on top so people can think oh look how interesting as they pass over it... Obviously sat-nav type applications should be able to cater for point restrictions, however the OSM idea is much more about recording what's there signed than about tagging for specific app's or renderers. I think the idea of tagging the bridge is odd, and failing to tag the way beneath irresponsible. If I see a maxheight on a bridge, I will *know* there is another layer above it. My 2p.. Mark ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Wed, Jul 29, 2009 at 4:42 PM, Mark Williams mark@blueyonder.co.uk wrote: Therefore maxheight is a property of the way going under the bridge, possibly 1 way if the road is fragmented in OSM, and ought to be on the whole road from where the sign is until after the bridge. Yup, that seems to be the consensus. And when there is no sign? I would suggest tagging only the part of the way that is physically restricted, i.e. physically under the bridge. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On 07/28/2009 11:45 AM, Christoph Böhme wrote: According to Wikipedia clearance [1] is the free space between a vehicle and the structure (i.e. bridge) it is passing through. The maximum height (and width) of the vehicle is -- at least for railways -- called loading gauge [2] while the dimensions of the structure are called structure gauge [3]. Thus, what we find on signs is the loading gauge. It may also be worth mentioning that there's another meaning of clearance when referring to vehicles: that of the free space beneath a vehicle (ground clearance). So it would seem that clearance always refers to free space below -- meaning that it's the bridge's clearance that is marked. This does not contradict that it is also the loading gauge of the vehicles passing underneath it... -Alex Mauer hawke signature.asc Description: OpenPGP digital signature ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 3:45 PM, Maarten Deenmd...@xs4all.nl wrote: Having a node shared between a bridge and the way underneath may solve one problem but introduces another (having to make a relation to indicate this physical route is not present). Agreed. maxheight needs to be applied to the road it applies to. Not the structure that is going over it. If you want to do that (which is not that uncommon, water maps do it all the time), introduce another key. Ok. So it seems the question now is, how should maxheight be applied to roads passing under bridges? The only reasonable and maintainable approach, in my opinion, is to apply it to the section of road that is physically under the bridge. Any objections? ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: Um...the way would also be close proximity to the bridge, because it passes under it... I don't see how finding a node near a bridge is a particularly elegant solution. And by random I mean the particular node you choose would be arbitrary and in an arbitrary position. And by arbitrary I mean without specific meaning. The solution depends on what problem you are trying to solve, if you are trying to find attributes of a bridge or restrictions of a way, my suggestion solves the restrictions of a way I'm not trying to solve attributes of a bridge. I was referring to the width of the bridge. And sure, A physical attribute like the bridge's full width, which differs to a restriction of maxwidth is just width=* maxwidth exists but I would say that OSM ways are stored as lines. Mathematically, I'm saying a point cannot be under a line, unless it is on it. OSM doesn't store lines, it stores nodes, it stores ways and which nodes are memebers of that way and it stores relations and which ways are members of that relation. You can easily locate any node within a certain radius of any given path (or line) between 2 nodes and do a database lookup which will spit out any results. This is something keep right already checks for so it's not difficult, just processor intensive on a large scale. If you want to be really picky about this you have to remember that even straight lines aren't straight as we're talking about a curved surface of a sphere so if it's straight on a 2 dimensional plane then it would be curved on a spherical one and vice versa. :) ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: I'm starting to like this idea. But the problem with this is how to define that section of way, so as not to introduce a maintenance You really don't want to pull on that thread, the same can be said for bridges or virtually any other reason a way is split, someone even made a comment about maxspeed splitting ways the other week. It's a much bigger discussion than maxheight and one that probably should be addressed and you would need to attack it as an overall problem, not just for one issue. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Roy Wallace wrote: On Tue, Jul 28, 2009 at 3:45 PM, Maarten Deenmd...@xs4all.nl wrote: Having a node shared between a bridge and the way underneath may solve one problem but introduces another (having to make a relation to indicate this physical route is not present). Agreed. maxheight needs to be applied to the road it applies to. Not the structure that is going over it. If you want to do that (which is not that uncommon, water maps do it all the time), introduce another key. Ok. So it seems the question now is, how should maxheight be applied to roads passing under bridges? The only reasonable and maintainable approach, in my opinion, is to apply it to the section of road that is physically under the bridge. Any objections? IMHO it is not that important if the way with the limit is only just beneath the bridge, or is somewhat longer or is applied to nodes on either side of a bridge. I recently came across this example where the way with the maxheight is a lot longer than strictly necessary. For every day uses this does not really pose a problem. http://www.openstreetmap.org/browse/way/25883025 Regards, Maarten ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 3:58 PM, John Smithdelta_foxt...@yahoo.com wrote: --- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: The solution depends on what problem you are trying to solve, if you are trying to find attributes of a bridge or restrictions of a way, my suggestion solves the restrictions of a way I'm not trying to solve attributes of a bridge. Well, if possible we should try and find a solution that solves both problems. However, thus far this doesn't seem possible, and the consensus does seem to be that restrictions of a way is of higher priority. But even for that, putting a node in an arbitrary location on a way still seems inelegant to me. OSM doesn't store lines, it stores nodes, it stores ways and which nodes are memebers of that way and it stores relations and which ways are members of that relation. A segment of a way is clearly a line between two points (nodes), without inherent width (sure, it may be specified with width=*, but it's not an inherent property of a way). Anyway, this is off topic. What do you think of my suggestion? That the restriction should be applied to the section of the way that is indeed physically *under* the bridge? ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 4:17 PM, Maarten Deenmd...@xs4all.nl wrote: IMHO it is not that important if the way with the limit is only just beneath the bridge, or is somewhat longer or is applied to nodes on either side of a bridge. I recently came across this example where the way with the maxheight is a lot longer than strictly necessary. For every day uses this does not really pose a problem. http://www.openstreetmap.org/browse/way/25883025 So the solution is do whatever you want? Hrmm... A couple of potential problems with this: What if someone later adds a way that intersects the way with the restriction? The restriction must then be removed from the part of the way that is beyond the bridge - but this user should not be expected to know that the restriction even exists... Also, for longer sections, it becomes less clear that the maxheight restriction is in regard to the bridge (versus the law, power lines, trees, buildings, or something else). For ways with multiple bridges in close proximity, it may become unclear which bridge the restriction applies to. etc etc... It gets a bit sloppy... ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Roy Wallace wrote: On Tue, Jul 28, 2009 at 4:17 PM, Maarten Deenmd...@xs4all.nl wrote: IMHO it is not that important if the way with the limit is only just beneath the bridge, or is somewhat longer or is applied to nodes on either side of a bridge. I recently came across this example where the way with the maxheight is a lot longer than strictly necessary. For every day uses this does not really pose a problem. http://www.openstreetmap.org/browse/way/25883025 So the solution is do whatever you want? Hrmm... A couple of potential problems with this: What if someone later adds a way that intersects the way with the restriction? The restriction must then be removed from the part of the way that is beyond the bridge - but this user should not be expected to know that the restriction even exists... Also, for longer sections, it becomes less clear that the maxheight restriction is in regard to the bridge (versus the law, power lines, trees, buildings, or something else). For ways with multiple bridges in close proximity, it may become unclear which bridge the restriction applies to. etc etc... It gets a bit sloppy... You are right. It is better to stay close around the limiting object. Regards, Maarten ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Maarten Deenmd...@xs4all.nl wrote: I recently came across this example where the way with the maxheight is a lot longer than strictly necessary. For every day uses this does not really pose a problem. Roy Wallace waldo000...@gmail.com wrote: A couple of potential problems with this: What if someone later adds a way that intersects the way with the restriction? The restriction must then be removed from the part of the way that is beyond the bridge - but this user should not be expected to know that the restriction even exists... This is self evident - we map what is on the ground, and we apply the restriction to the section of the way for which the restriction applies. If a service road for a carpark has a restriction for the entire carpark, even if it is just caused by the danger associated with one or two low-hanging sprinklers, or a pipe, the restriction applies to the entire service road, and not just directly under the sprinklers. If a motorway has a restriction for a motorway section, because of a low bridge, the restriction applies to the section. A higher vehicle is not permitted on that motorway section. If a country lane has a low bridge, the restriction usually only applies to the road section under the bridge, a higher vehicle is usually unrestricted except when it passes the bridge. Applying a restriction to a way where there isn't a restriction, is clearly an error, and should be corrected by the next OSMer to pass that way. Ian. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 08:11:21AM +1000, Roy Wallace wrote: There are two issues here: 1) what should be tagged and 2) what should it be tagged with. For 1), what should be tagged? Definitely the bridge. For two reasons: firstly, clearance under a bridge is an attribute of the bridge. What of bridges that cross multiple ways of different heights? Simon -- A complex system that works is invariably found to have evolved from a simple system that works.—John Gall signature.asc Description: Digital signature ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009 08:11:21 +1000, Roy Wallace waldo000...@gmail.com wrote: On Mon, Jul 27, 2009 at 9:47 PM, John Smithdelta_foxt...@yahoo.com wrote: --- On Mon, 27/7/09, Roy Wallace waldo000...@gmail.com wrote: I think the bridge should be tagged. There was an overwhelming response on the main talk list that this be tagged as maxheight on the way that has the restriction, ie you can't go under the bridge unless you are under x metres. There are two issues here: 1) what should be tagged and 2) what should it be tagged with. For 1), what should be tagged? Definitely the bridge. For two reasons: firstly, clearance under a bridge is an attribute of the bridge. Wrong. It is an attribute of the ways below the bridge. because: 1) Multiple ways below a round bridge have different maxheight-values (happens in my place all the time) 2) Not only bridges have maxheight but also parking-lots, tunnels, ... 3) The way below the bridge does not intersect the bridge at all. There is no reference from the street below to indicate that there is a bridge at all. You would have to analyse the location and vector of all other ways in the map as one of them could be a bridge and you would have to do that for each and any way-segment you want to evaluate for routing. Bad idea. For 2), what should it be tagged with? I concede that a bridge tagged with height could be misinterpreted (as the actual height of the bridge or bridge construction), as could maxheight (as referring to a restriction involved with traveling on top of the bridge). We have tags maxheight, maxwidth, maxspeed, ... ele and height that are in wide use and have a well established meaning, well documented in the wiki. Period. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 08:01:45AM +0100, Simon Ward wrote: What of bridges that cross multiple ways of different heights? Sorry. I see that this has been commented on elsewhere in the thread. Simon -- A complex system that works is invariably found to have evolved from a simple system that works.—John Gall signature.asc Description: Digital signature ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, marcus.wolsc...@googlemail.com marcus.wolsc...@googlemail.com wrote: 2) Not only bridges have maxheight but also parking-lots, tunnels, ... and trees even if they aren't explicitly signed. http://www.mirror.co.uk/news/top-stories/2008/05/20/shocked-witnesses-describe-horror-bus-smash-115875-20423991/ ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: For maxspeed (your example), the restriction should be applied to the Exactly, you may have to break a way up to apply maxspeed tags to several different parts of what was originally a single way. Exactly the same as a bridge, it is part of longer way but needs to be broken up to indicate the start/end of the bridge etc etc etc ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 09:07:56AM +0200, marcus.wolsc...@googlemail.com wrote: The way below the bridge does not intersect the bridge at all. There is no reference from the street below to indicate that there is a bridge at all. You would have to analyse the location and vector of all other ways in the map as one of them could be a bridge and you would have to do that for each and any way-segment you want to evaluate for routing. Bad idea. I think this is the best reason I've read to tag the street below. I wouldn't want my poor Neo Freerunner to perform queries like this just for some routing. Markus sketches a little too grim image, as a good data structure will prevent you from having to iterate all segments, but still his point is valid. Cheers, -- Sybren Stüvel http://stuvel.eu/ http://www.flickr.com/photos/sybrenstuvel signature.asc Description: Digital signature ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Roy Wallace waldo000...@gmail.com writes: On Tue, Jul 28, 2009 at 10:10 AM, Stephen Hopeslh...@gmail.com wrote: No, you're wrong here. Maxheight is an element of the way that goes under the bridge. It is caused by the bridge, but it is not part of the bridge. You're saying that the clearance under a bridge is not an attribute of the bridge? I'm not at all convinced of that. But it is subjective, so we may have to agree to disagree. The clearance under the bridge is, from the point of view of navigating, a property of the road under the bridge. You don't care when driving on the bridge - you can when going under it. That's where the max clearance signs are. I have never seen a sign on a bridge showing the clearance under it. (The point that a bridge could have height obstructions on it is also valid.) In fact the clearance is a joint property of the location of the underside of the bridge and the top of the road. Lowering the road a meter improves clearance, so saying this is just about the bridge makes no sense. pgpHxew0sECwQ.pgp Description: PGP signature ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
2009/7/28 Liz ed...@billiau.net: To return to the bridge the following attributes of the bridge and the road underneath it all need to be considered a) Height of bridge height tag on bridge way b) Height above sea level of the bridge ele tag on bridge way c) Max height of the arch of the bridge above the roadway - a) d) Max height of a vehicle which can drive under the bridge, which if the bridge maxheight tag on the way under the bridge if you want to distinguish this from e), use a new tag (i.e. illegal but possible, e.g. clearance), but still on the way under the bridge. e) Max height of a vehicle which the engineer said was permitted to drive under the bridge maxheight tag on the way under the bridge If you want to explain explicitly in the data, why there is a height restriction on the way, put all involved ways in a bridge-relation. cheers, Martin ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Roy Wallace waldo000...@gmail.com schrieb: On Tue, Jul 28, 2009 at 11:04 AM, Ross Scanloni...@4x4falcon.com wrote: Does this mean the bridge has a clearance of 2.8 or the road under the bridge has a clearance of 2.8. To me this would suggest the bridge has a limit of 2.8 ie vehicles travelling over the bridge can not be above 2.8 high. I'd suggest that if the bridge has a height limit, ie clearance, then the bridge is tagged with max_height. If the road under the bridge has a height limit, ie clearance, then the road is tagged. Sorry, maybe this is a language issue. In my mind, height limit of a way refers to maximum height *above* the way, whereas clearance of a way infers maximum height *under* the way. Maybe clearance isn't the best word for this - please suggest others. According to Wikipedia clearance [1] is the free space between a vehicle and the structure (i.e. bridge) it is passing through. The maximum height (and width) of the vehicle is -- at least for railways -- called loading gauge [2] while the dimensions of the structure are called structure gauge [3]. Thus, what we find on signs is the loading gauge. Christoph [1] http://en.wikipedia.org/wiki/Clearance [2] http://en.wikipedia.org/wiki/Loading_gauge [3] http://en.wikipedia.org/wiki/Structure_gauge ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Mon, Jul 27, 2009 at 9:47 PM, John Smithdelta_foxt...@yahoo.com wrote: --- On Mon, 27/7/09, Roy Wallace waldo000...@gmail.com wrote: I think the bridge should be tagged. There was an overwhelming response on the main talk list that this be tagged as maxheight on the way that has the restriction, ie you can't go under the bridge unless you are under x metres. There are two issues here: 1) what should be tagged and 2) what should it be tagged with. For 1), what should be tagged? Definitely the bridge. For two reasons: firstly, clearance under a bridge is an attribute of the bridge. Secondly, it is not possible to refer to the section of the way that is under the bridge, because the bridge is a way with zero width. The only alternative is to tag the entire length of any way that goes under the bridge or some arbitrary length of any way that goes under the bridge. I think these alternatives are undesirable at best - misleading and messy at worst. For example, it's kind of like tagging any house that's next to a park as next_to_a_park=yes, rather than tagging the big grassy area as leisure=park (yes, this is an exaggeration, but the analogy is tagging the thing that is affected by something rather than tagging the something itself). For 2), what should it be tagged with? I concede that a bridge tagged with height could be misinterpreted (as the actual height of the bridge or bridge construction), as could maxheight (as referring to a restriction involved with traveling on top of the bridge). Therefore, I suggest a new tag, clearance. A new tag should be created when the current tags do not describe things adequately, which I think is what has happened in this case. Thoughts? ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 10:10 AM, Stephen Hopeslh...@gmail.com wrote: No, you're wrong here. Maxheight is an element of the way that goes under the bridge. It is caused by the bridge, but it is not part of the bridge. You're saying that the clearance under a bridge is not an attribute of the bridge? I'm not at all convinced of that. But it is subjective, so we may have to agree to disagree. It is the road under the bridge that has the limitation, not the bridge. Divided roads often have different max heights on each side, but it is one level bridge over the top. Good point, though I would suspect this is relatively rare (i.e. I've never seen this). Max-height can be caused by overhanging trees, low wires, odd road signs that stick out over the road, even buildings or roadside rocks that bulge out over the road. Whatever the cause, it is the road itself that is affected, and should be tagged. I disagree. We should be tagging things, not tagging the effect of things. On a motorway, the max height section can be several km long - the distance between exits, and it is all covered by the same limitation, legally. On other roads it may be only a few meters, and could be covered by a node tag. Sounds like a maintenance nightmare. I'm also not sure that a clearance under a bridge is equivalent to a legal limitation for the section of motorway between the exits before and after the bridge, as you say. And what if a motorway and bridge are tagged, but exits are missing, etc. Just sounds a lot harder to maintain than tagging the bridge itself. Can you explain what you mean by may be only a few meters, and could be covered by a node tag? If you can specify an exact preferred way of tagging this (and document it on the wiki), I may well be convinced. Cheers, Roy ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 10:15 AM, Cameronosm-mailing-li...@justcameron.com wrote: I think tag the part of the way that is signed. Generally before bridges there is a sign informing road users of the bridge's restrictions. Sometimes they will offer an alternate route for larger vehicles. So tag from the nearest junction if available or the sign. Funnily enough, where I have been mapping the sign is always on the bridge itself. Anyway, I think we should be tagging what the sign is referring to, independent of the sign itself. A clearance tag could just as easily be misinterpreted as the maxheight tag. I don't see how. bridge=yes; clearance=2.8... Roy ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009, Roy Wallace wrote: On Tue, Jul 28, 2009 at 10:10 AM, Stephen Hopeslh...@gmail.com wrote: No, you're wrong here. Maxheight is an element of the way that goes under the bridge. It is caused by the bridge, but it is not part of the bridge. You're saying that the clearance under a bridge is not an attribute of the bridge? I'm not at all convinced of that. But it is subjective, so we may have to agree to disagree. It is the road under the bridge that has the limitation, not the bridge. Divided roads often have different max heights on each side, but it is one level bridge over the top. snip we're arguing about matters regarding the logic of choices (as usual) then the logic of the name applied to the choice, which gets into philosophical arguments which remind me of Plato. http://en.wikipedia.org/wiki/Plato The problem is that at a time in the past a decision was made (Principle A) whose logic is now questioned. A lot has been uploaded onto the server using Principle A, which will have to be reworked if Principle B succeeds Principle A. So regardless of the logic, people will support Principle A because of the work involved in change. Just look at the work involved by the API change from 0.5 to 0.6 To return to the bridge the following attributes of the bridge and the road underneath it all need to be considered Height of bridge Height above sea level of the bridge Max height of the arch of the bridge above the roadway Max height of a vehicle which can drive under the bridge, which if the bridge is an arch must be less than the max height of the arch Max height of a vehicle which the engineer said was permitted to drive under the bridge so now I have 5 height measures some of which belong to the road and some to the bridge, and some to both. then we need unambiguous tags to refer to these 5 concepts and translations of them all. :-) ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Liz schrieb: To return to the bridge the following attributes of the bridge and the road underneath it all need to be considered Height of bridge Height above sea level of the bridge Max height of the arch of the bridge above the roadway Max height of a vehicle which can drive under the bridge, which if the bridge is an arch must be less than the max height of the arch Max height of a vehicle which the engineer said was permitted to drive under the bridge so now I have 5 height measures some of which belong to the road and some to the bridge, and some to both. then we need unambiguous tags to refer to these 5 concepts and translations of them all. :-) What about a max height of vehicles passing *over* the bridge? there are quite a lot of bridges which have support structures limiting he height of vehicles passing over it. how do you distinguish this, and how do you make it clear to every mapper what is what? -- Dirk-Lüder Deelkar Kreie Bremen - 53.0901°N 8.7868°E signature.asc Description: OpenPGP digital signature ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009 10:34:00 +1000, Roy Wallace waldo000...@gmail.com wrote: On Tue, Jul 28, 2009 at 10:15 AM, Cameronosm-mailing-li...@justcameron.com wrote: I think tag the part of the way that is signed. Generally before bridges there is a sign informing road users of the bridge's restrictions. Sometimes they will offer an alternate route for larger vehicles. So tag from the nearest junction if available or the sign. Funnily enough, where I have been mapping the sign is always on the bridge itself. Anyway, I think we should be tagging what the sign is referring to, independent of the sign itself. A clearance tag could just as easily be misinterpreted as the maxheight tag. I don't see how. bridge=yes; clearance=2.8... Roy ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk I am writing a proposal for a clearance-tag, I will send it out tomorrow. Link is posted from the tag-height discussion if you want to have a look at the draft -- Brgds Aun Johnsen via Webmail ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009, Dirk-Lüder Kreie wrote: Liz schrieb: To return to the bridge the following attributes of the bridge and the road underneath it all need to be considered Height of bridge Height above sea level of the bridge Max height of the arch of the bridge above the roadway Max height of a vehicle which can drive under the bridge, which if the bridge is an arch must be less than the max height of the arch Max height of a vehicle which the engineer said was permitted to drive under the bridge so now I have 5 height measures some of which belong to the road and some to the bridge, and some to both. then we need unambiguous tags to refer to these 5 concepts and translations of them all. :-) What about a max height of vehicles passing over the bridge? there are quite a lot of bridges which have support structures limiting he height of vehicles passing over it. how do you distinguish this, and how do you make it clear to every mapper what is what? I'm happy to admit I've missed a 6th height measure - missing possible scenarios is one of our problems in tagging. This just came up on the talk_au where this discussion is running in parallel ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Funnily enough, where I have been mapping the sign is always on the bridge itself. Anyway, I think we should be tagging what the sign is referring to, independent of the sign itself. even if the sign is on the bridge structure it is a limitation valid for the road passing under the bridge. the maxheight must be on the road where it is valid one bridge can cross multiple roads with different maxheight limtations. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 11:04 AM, Ross Scanloni...@4x4falcon.com wrote: Does this mean the bridge has a clearance of 2.8 or the road under the bridge has a clearance of 2.8. To me this would suggest the bridge has a limit of 2.8 ie vehicles travelling over the bridge can not be above 2.8 high. I'd suggest that if the bridge has a height limit, ie clearance, then the bridge is tagged with max_height. If the road under the bridge has a height limit, ie clearance, then the road is tagged. Sorry, maybe this is a language issue. In my mind, height limit of a way refers to maximum height *above* the way, whereas clearance of a way infers maximum height *under* the way. Maybe clearance isn't the best word for this - please suggest others. My main point is that when there is a maximum height under a way, this should be tagged as an attribute of that way, not of the ways that pass under it. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 11:14 AM, Apollinaris Schoellascho...@gmail.com wrote: one bridge can cross multiple roads with different maxheight limtations. This is a good argument in favour of tagging the ways that pass under a bridge instead of the bridge. But I think it should be weighed against the arguments for the other method. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009, Roy Wallace wrote: My main point is that when there is a maximum height under a way, this should be tagged as an attribute of that way, not of the ways that pass under it. Here I cannot agree When I travel over the bridge I am not interested in the maximum height of the way which travels under the bridge. When I travel under the bridge I am interested in the height limitation. Going back to my multipart specification, trying to really comprehend the logic the height of the arch is a property of the bridge. the max height which can go under the bridge is a property of the way / node beneath it note that counter-intuitively, height max height clearance ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 11:33 AM, Lized...@billiau.net wrote: When I travel over the bridge I am not interested in the maximum height of the way which travels under the bridge. When I travel under the bridge I am interested in the height limitation. Ah, perhaps our difference in opinion stems from our different perspectives - your emphasis on when I travel vs my emphasis on, perhaps, when I look at a map, or when I conceptualise the world. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 12:26 PM, John Smithdelta_foxt...@yahoo.com wrote: I think everyone is thinking of this in one of 2 ways, it's either an attribute of the bridge, or a restriction of the way under the bridge. Agreed. And it's clear that both ways of thinking are probably valid. As for using a node to indicate maxheight, this seems to me to be a very clean way of dealing with it, since any routing software would only need one obstacle to reject that section of way and find another path. Can you please explain exactly what you mean by using a node to indicate maxheight? This seems to be different from the posts which seemed to suggest tagging, e.g. sections of motorway between exits, etc. Like I said, my main argument for tagging the bridge is that it's unambiguous and easy to implement and maintain. If you have a consistent scheme for tagging the ways which pass under bridges, which is unambiguous and easy to implement and maintain, please share and document on the wiki :) Cheers, Roy ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: Agreed. And it's clear that both ways of thinking are probably valid. As of time of writing maxheight is the only valid one and I don't think we need or should have 2 tags to indicate the same thing in 2 different ways. Can you please explain exactly what you mean by using a node to indicate maxheight? This seems to be different from the Someone posted about this earlier, have a node on the way effected, near or under the bridge, rather than splitting the way and then tagging that node as maxheight or clearence might be the better option that making a new section of way. However maxheight is currently only applicable to ways not nodes. posts which seemed to suggest tagging, e.g. sections of motorway between exits, etc. Like I said, my main argument for tagging the bridge is that it's unambiguous and easy to implement and maintain. It's not hard or ambiguous, it just means splitting a way under the bridge similar to splitting a bridge. If you have a consistent scheme for tagging the ways which pass under bridges, which is unambiguous and easy to implement and maintain, please share and document on the wiki :) It's a little more complicated then that, at present there was agreement on maxheight as a restriction tag and that is perfectly valid as far as I'm concerned. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009, Roy Wallace wrote: On Tue, Jul 28, 2009 at 12:26 PM, John Smithdelta_foxt...@yahoo.com wrote: I think everyone is thinking of this in one of 2 ways, it's either an attribute of the bridge, or a restriction of the way under the bridge. Agreed. And it's clear that both ways of thinking are probably valid. As for using a node to indicate maxheight, this seems to me to be a very clean way of dealing with it, since any routing software would only need one obstacle to reject that section of way and find another path. Can you please explain exactly what you mean by using a node to indicate maxheight? This seems to be different from the posts which seemed to suggest tagging, e.g. sections of motorway between exits, etc. Like I said, my main argument for tagging the bridge is that it's unambiguous and easy to implement and maintain. If you have a consistent scheme for tagging the ways which pass under bridges, which is unambiguous and easy to implement and maintain, please share and document on the wiki :) Cheers, Roy I don't think that we have a consistent clear unambiguous easily_maintained and implemented system yet. It certainly isn't up to document on the wiki standard. But a few more posts from all comers and we could be close to 'clear' and 'unambiguous'. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: Ah, perhaps our difference in opinion stems from our different perspectives - your emphasis on when I travel vs my emphasis on, perhaps, when I look at a map, or when I conceptualise the world. That was the basis of the 2 sets of logic, one is a restriction, the other is a physical attribute. maxheight is a restriction so belongs attached to the way that would be restricted. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 2:57 PM, John Smithdelta_foxt...@yahoo.com wrote: As of time of writing maxheight is the only valid one and I don't think we need or should have 2 tags to indicate the same thing in 2 different ways. I meant there's two ways of conceptualising the distance below a bridge (as an attribute or a restriction). I'm not suggesting we need 2 different tags. I'm quite happy to tag it as a restriction, if we can agree on how it should be implemented. have a node on the way effected, near or under the bridge, rather than splitting the way and then tagging that node as maxheight or clearence might be the better option that making a new section of way. However maxheight is currently only applicable to ways not nodes. ... It's not hard or ambiguous, it just means splitting a way under the bridge similar to splitting a bridge. I would at least suggest that - if maxheight is applied to a node, as you suggest - the node should be *shared* by the bridge (way) and the way passing under. This makes it clearer that maxheight is specifically referring to the bridge clearance. Also, if someone is checking, for example, whether maxheight is specified for a particular bridge/way, they don't have to go searching for some random node near the bridge. By the way, you can't place a node under the bridge, unless it is indeed shared by the bridge, as all ways have zero width (right?). ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
--- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: I would at least suggest that - if maxheight is applied to a node, as you suggest - the node should be *shared* by the bridge (way) and the way passing under. This makes it clearer that maxheight is The problem with this is that 2 ways sharing a node are physically connected and this wouldn't be the case as one passes over the other. specifically referring to the bridge clearance. Also, if someone is checking, for example, whether maxheight is specified for a particular bridge/way, they don't have to go searching for some random node near the bridge. Searching for a node near the bridge would be easier than searching for a way since the node would be in close proximity to the bridge and you search by lat/lon rather than random nodes. By the way, you can't place a node under the bridge, unless it is indeed shared by the bridge, as all ways have zero width (right?). You can use the maxwidth tag to indicate the maximum width and object must be to pass a restriction on the way, like an underpass of a bridge :) ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, 28 Jul 2009, Roy Wallace wrote: By the way, you can't place a node under the bridge, unless it is indeed shared by the bridge, as all ways have zero width (right?). Logically you can as they are on different layers. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 3:30 PM, John Smithdelta_foxt...@yahoo.com wrote: --- On Tue, 28/7/09, Roy Wallace waldo000...@gmail.com wrote: I would at least suggest that - if maxheight is applied to a node, as you suggest - the node should be *shared* by the bridge (way) and the way passing under. This makes it clearer that maxheight is The problem with this is that 2 ways sharing a node are physically connected and this wouldn't be the case as one passes over the other. Ah, of course. Problem. Searching for a node near the bridge would be easier than searching for a way since the node would be in close proximity to the bridge and you search by lat/lon rather than random nodes. Um...the way would also be close proximity to the bridge, because it passes under it... I don't see how finding a node near a bridge is a particularly elegant solution. And by random I mean the particular node you choose would be arbitrary and in an arbitrary position. And by arbitrary I mean without specific meaning. By the way, you can't place a node under the bridge, unless it is indeed shared by the bridge, as all ways have zero width (right?). You can use the maxwidth tag to indicate the maximum width and object must be to pass a restriction on the way, like an underpass of a bridge :) I was referring to the width of the bridge. And sure, maxwidth exists but I would say that OSM ways are stored as lines. Mathematically, I'm saying a point cannot be under a line, unless it is on it. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
Roy Wallace wrote: On Tue, Jul 28, 2009 at 2:57 PM, John Smithdelta_foxt...@yahoo.com wrote: As of time of writing maxheight is the only valid one and I don't think we need or should have 2 tags to indicate the same thing in 2 different ways. I meant there's two ways of conceptualising the distance below a bridge (as an attribute or a restriction). I'm not suggesting we need 2 different tags. I'm quite happy to tag it as a restriction, if we can agree on how it should be implemented. have a node on the way effected, near or under the bridge, rather than splitting the way and then tagging that node as maxheight or clearence might be the better option that making a new section of way. However maxheight is currently only applicable to ways not nodes. ... It's not hard or ambiguous, it just means splitting a way under the bridge similar to splitting a bridge. I would at least suggest that - if maxheight is applied to a node, as you suggest - the node should be *shared* by the bridge (way) and the way passing under. This makes it clearer that maxheight is That seems a very bad idea. Nodes are generally used to indicate a physical path between two ways. Having a node shared between a bridge and the way underneath may solve one problem but introduces another (having to make a relation to indicate this physical route is not present). specifically referring to the bridge clearance. Also, if someone is checking, for example, whether maxheight is specified for a particular bridge/way, they don't have to go searching for some random node near the bridge. But why am I interested in a bridge clearance? I am interested in the maximum height my vehicle can have while traveling down a road. I can argue exactly like you that I don't want to go searching for some random node near the road I'm travelling on to see if it is possible to do so. If you are on the bridge, you are not really interested if the bridge poses a limit to the way underneath it. IMHO there are people here trying too hard to model things. maxheight does not necessarily need to be applied to bridges only. It could also be powercables or tramlines or low streetlighting or branches or whatever. maxheight needs to be applied to the road it applies to. Not the structure that is going over it. If you want to do that (which is not that uncommon, water maps do it all the time), introduce another key. Regards, Maarten ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
Re: [OSM-talk] [talk-au] maxheight/height
On Tue, Jul 28, 2009 at 3:31 PM, Lized...@billiau.net wrote: On Tue, 28 Jul 2009, Roy Wallace wrote: By the way, you can't place a node under the bridge, unless it is indeed shared by the bridge, as all ways have zero width (right?). Logically you can as they are on different layers. Yes, that is under as in closer to the centre of the earth, but not under as in if you look up you see the bottom of the bridge. ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
[OSM-talk] [talk-au] maxheight/height
Liz edodd at billiau.net wrote: On Tue, 28 Jul 2009, Roy Wallace wrote: By the way, you can't place a node under the bridge, unless it is indeed shared by the bridge, as all ways have zero width (right?). Logically you can as they are on different layers. That is not going to work. There is always a way with no layer connected to a way with a layer tag. How would you distinguish between the two? Making an agreement crossing ways with different layer tag is not good enough. When is it crossing? When the ways continue on all four sides of the node? In right angles only? What when two ways are in an acute angle? Regards, Maarten ___ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
