OpenStreetMap
More and more people want to tag complicated access restriction, but the current scheme often isn't sufficient enough for that. That is why I put my thoughts for a refactored access scheme in a proposal:
osm.wiki/Proposed_features/access_restrictions_1.5
Of course you will never be able to handle all the access restrictions in the world. The goal should be to bring some structure and naming conventions to the current access tags and values and handle special cases a bit better than right now.
Discussion
Comment from z-dude on 8 May 2011 at 01:22
stuff like
access:lgv!school_zone#time=Mo,We 08:00-18:00
and
access!ZTL#time=Mo-Th 06:30-18:00; Fr 06:30-18:00,23:00-24:00; Sa 00:00-03:00,14:00-18:00,23:00-24:00; Su 00:00-03:00
end up looking more like computer code rather than a human readable description.
Comment from flaimo on 8 May 2011 at 09:50
that is not a new kind of notation for proposal. that is the normal opening_hours syntax already in use: osm.wiki/Opening_hours
Comment from Zartbitter on 9 May 2011 at 09:49
Stuff like noted above will only be used by a few users and fucked up by mistake by most other users.
BTW the opening_hours syntax is quite new, too
Comment from davespod on 9 May 2011 at 23:06
The notation used in the value is already in use for opening hours. The notation used in the key ("!" to define a condition, "#" to prefix a modifier) most definitely is not. As alexz says, this is moving away from being human readable. Tags work best when you can get a pretty good idea of what they mean without reading reams of documentation. If you want a tag to catch on (and that surely is the point?), you need to be a little kinder to the mapper.
OK, the opening hours may be slightly difficult to read in that format, but there are no odd punctuation characters carrying unexpected meanings (separating items in a list is a pretty common use for a semi-colon).
Comment from z-dude on 10 May 2011 at 04:33
on a positive note
I like the length, axle weight, height, and trailer restrictions, as truckers are more interested in that.
some suggestions
dawn and dusk times - to add to the list.. (playgrounds speed limits are slow from dawn to dusk - defined as a certain number of minutes before and after sunset)
replace the ? with : that way you get
access:bicycle=yes
access:bicycle:wet=no for slippery wooden bridges.
I thought the ! symbol was a mathematical 'not' operator.
I've seen 'hgv' used... is this an offshoot of lgv?
some streets in the UK can't fit the North American intermodal sized trailers (these are boxcar sized trailers which fit onto trains in North America, and go onto container ships)
I'd suggest keeping the majority of the tagging ideas in this proposal.
When I first posted the 'non human readable' comment, I was going with my gut feeling, and someone else pointed out it was the mathematical/conditional operators.. I think I agree with them.
There's a lot of good stuff in your proposal, I hope most of it stays.
Comment from flaimo on 10 May 2011 at 07:44
1) there need to be different separators than just the ":" otherwise parsers would never be able to differentiate between the different parts, without always keeping up to date lists of the access tree, conditions and modifiers.
2) every day there are questions popping up like "how do i tag access restriction xyz IF its wet/winter/dark/…". you can't keep simple tags and at the same time cover conditions. at some point you have to define some sort of "if" in either the key or value field. i decided to go with the key field. if you got a better solution that is easier to read without loosing functionality, than please post them to the comments of the proposal. also don't forget that access restrictions are probably the most complicated thing to tag in OSM, because they are complicated by themselves already.
3) i will add dusk/dawn
4) heavy goods vehicle (hgv) isn't used anymore. according to http://en.wikipedia.org/wiki/Large_goods_vehicle. it is called large good vehicle (lgv)
5) only if you come from a programming background you might confuse the "!" with a NOT operator. most people are not programmers. please post suggestions for a better symbol to the wiki comments. one symbol that might be possible is the "#" symbol, since i replaced that one with the "." symbol for modifiers.
Comment from davespod on 10 May 2011 at 12:56
Sorry to be so negative. I am not trying to do down your efforts to record complex information in OSM. I am just concerned that undue complexity is the best way to ensure such tags are never used. I would not be too worried if the tagging complexity only affected the complex situations, but if I understand your proposal correctly, it would affect quite simple scenarios, too.
So we currently tag one way streets as oneway=yes. Pretty obvious and easy to remember. Under the proposal we would tag them as access:direction=forward. Where that restriction does not apply to bikes, people variously tag bicycle:oneway=no or oneway:bicycle=no. Under the proposal, we would have to tag access:bicycle.direction=both.
But you are right. This is not the place for comments. I will add them to the wiki talk page.
Comment from flaimo on 10 May 2011 at 14:26
since i use the access namespace in the proposal, i don't have to worry about backward compatibility. i used this change to phrase some keys (or in this case called modifiers) to be more neutral, since they can also be used for defining conditions. that is also why "opening_hours" isn't called "opening_hours" but rather "time" because used in combination with a condition it could also be interpreted as "closed_hours".