Proposal:Default layer for bridge and tunnel

default layer value for bridge and tunnel
Proposal status:	Rejected (inactive)
Proposed by:	Canabis
Tagging:	bridge, tunnel, layer=-1, 1
Applies to:	,
Definition:	Set default layer=1 for bridge=yes and layer=-1 for tunnel=yes
Statistics:
Draft started:	2010-12-11
RFC start:	2010-12-15
Vote start:	2011-01-11
Vote end:	2011-01-25

Proposal

This was already discussed with no results. I propose to introduce default layer value for bridge=yes and tunnel=yes. Those will be layer=1 and layer=-1 respectively. All other elements will stay as is, i.e. with layer=0 by default.

Rationale

• Statistics for bridge=yes:

1. Only 72.7% of the objects tagged with bridge=yes have layer=* tag
2. Among these objects 95.5% use layer=1
3. Other 4.3% use layer > 1

Some of the objects which are tagged with bridge=yes contain incorrect tags, for example, later=1, layer=!, layer=01, layer=a, layer=level1, layer=one, layer=q1, layere=1, layers=+1

• Statistics for tunnel=yes:

1. Only 69.3% of the objects tagged with tunnel=yes have layer=* tag
2. Among these objects 94.7% use layer=-1
3. Other 4.1% use layer < -1 and 1.1% use layer > 0

Some of the objects which are tagged with tunnel=yes contain incorrect tags, for example, layer=.1, layer=.-1, layer=/1, layer=1-, layer=-1#, layer=layer

• The mentioned statistics shows that tag layer=* is often omitted for bridges and tunnels. There is a chance that it is not set even for the bridges and tunnels that cross other ways. This leads to uncertainty and with current approach without default layer value often indicates an error in mapping. See #Examples.

• Why should we put efforts in defining facts which are obvious in majority of cases? And when there is an exception it could always be clarified. Bridge with layer=1 is just like water=yes + color=colorless. Of course, water could be white, red, and of many other colors. But the vast majority of water is colorless, and who would care to search some colorless water? If you're searching for a white water, you say: find me some white water. Same rationale makes it redundant to specify that a bridge is above the ground and tunnel is under the ground.

• Specifying layer=1 and layer=-1 respectively for bridge=yes and tunnel=yes increases the amount of data that leads to redundancy.

Examples

Uncertainties with bridges without layer=*:

1. http://osm.org/go/uo83f6g9A--
2. http://osm.org/go/ZVJf3DP7h--
3. http://osm.org/go/ZVJSKTegG--

And many other.

Uncertainties with tunnels without layer=*:

1. http://osm.org/go/0CFKZeNw
2. http://osm.org/go/kagX5R8
3. http://osm.org/go/euro4JUQx--

And many other.

Tagging

For mapping a bridge, use just bridge=yes without layer=1. If the default value of layer=1 is not suitable (there are already layers defined at the same cross), add layer=0/2...4 or even -1...-4.

For mapping a tunnel, use just tunnel=yes without layer=-1. If the default value of layer=-1 is not suitable (there are already layers defined at this spot), add layer=0/-2...-4 or even 1...4.

Applies to

, probably to .

Rendering

Renderers should draw objects with bridge=yes tag but without layer=* tag, as if they had layer=1, and tunnel=yes assumes layer=-1 as default value.

Today many renderers already draw bridges over and tunnels under other objects by default.

Features/Pages affected

1. Layer
2. Key:layer
3. Bridge
4. Tunnel
5. Relations/Proposed/Bridges and Tunnels
6. JOSM/Validator
7. Renderers: Osmarender, Mapnik, etc.
8. Category:Outputs: GPS Maps From OSM Data, OSM Map On Garmin, etc.

Maybe more?

Comments

Please discuss and comment at Talk.

Voting

Wiki tip: Type {{vote|yes/no}} to approve/oppose this proposal, type 4 tildes like: ~~~~ to sign your user name & date. You can add a short comment, but please use the talk page where appropriate.

• I approve this proposal. --Canabis 10:47, 11 January 2011 (UTC)
• I like this proposal. --Ilis 11:27, 11 January 2011 (UTC)
• I oppose this proposal. --Hind 11:50, 11 January 2011 (UTC)
• I oppose this proposal. --Komяpa 12:08, 11 January 2011 (UTC)
• I don't like this proposal. -- Miroff 12:17, 11 January 2011 (UTC)
• I approve this proposal. --Teddych 14:17, 11 January 2011 (UTC)
• I am indifferent to this proposal. --Zverik 15:01, 11 January 2011 (UTC)
• I oppose this proposal. --AMDmi3 15:47, 11 January 2011 (UTC)
• I don't like this proposal. --Kudrdima 15:49, 11 January 2011 (UTC)
• I oppose this proposal. --Wowik 18:19, 11 January 2011 (UTC)
• I oppose this proposal. --dedNikifor 19:36, 11 January 2011 (UTC)
• I oppose this proposal. --Sev 20:43, 11 January 2011 (UTC)
• I don't like this proposal. --Lyx 21:12, 11 January 2011 (UTC)
• I don't like this proposal. --Renaud 22:09, 11 January 2010 (UTC)
• I don't like this proposal. Loir 22:33, 11 January 2011 (UTC)
• I like this proposal. but would prefer a default of 1/2 and -1/2. --NE2 23:16, 11 January 2011 (UTC)
• I oppose this proposal. -- rickmastfan67 03:19, 12 January 2011 (UTC)
• I oppose this proposal. --Lulu-Ann 09:19, 12 January 2011 (UTC) Not sensible. Assumptions can be made by the renderer, not in the data.
• I oppose this proposal. Ikz 11:30, 12 January 2011 (UTC)
• I oppose this proposal. VikDD 10:23, 13 January 2011 (UTC)
• I like this proposal. Gps-Max 11:02, 14 January 2011 (UTC)
• I approve this proposal. /al 10:45, 17 January 2011 (UTC)
• I oppose this proposal. "Invisible" layer tags can cause hard-to-understand bugs. --Tordanik 11:08, 17 January 2011 (UTC)
• I oppose this proposal. This discussion is very old already and it was already decided at the time that a default layer value is a bad idea. --Eimai 11:36, 17 January 2011 (UTC)
• I oppose this proposal. reasons are given above. Less defaults we use, better data we get IMHO. Don't be lazy -- Dieterdreist 12:12, 17 January 2011 (UTC)
• I oppose this proposal. You're 'aving a larf, surely? SomeoneElse 13:16, 17 January 2011 (UTC)
• I approve this proposal. --Pobice 19:29, 17 January 2011 (UTC)
• I oppose this proposal. --Bk 01:03, 18 January 2011 (UTC)
• I oppose this proposal. Pnorman 02:05, 18 January 2011 (UTC)
• I like this proposal. We already have default tags (who is tagging oneway=no ?), so why not on bridges/tunnels ? --Pieren 13:39, 18 January 2011 (UTC)
• I don't like this proposal. --Fabi2 22:30, 18 January 2011 (UTC)
• I approve this proposal. -- There is an important rule for API builders: if some value is used in majority of cases, it should be set as default value. This proporsal follows it --Osmisto 11:21, 19 January 2011 (UTC)
• I oppose this proposal. For more than 2 years, the documentation of key layer says that objects without a layer tag is assumed to be on layer 0. I also believe that this change will make the tagging standards more complex. -- Nic 16:45, 19 January 2011 (UTC)
• I approve this proposal. Renderers already assume this (or maybe ±½) for good reason. Let's adjust rules to usage. And honestly, I like to be lazy. --Fkv 08:32, 20 January 2011 (UTC)
• I approve this proposal. --luch86 13:30, 20 January 2011 (UTC)
• I oppose this proposal. --polderrunner 20:10, 20 January 2011 (UTC)
• I oppose this proposal. chris66 19:04, 21 January 2011 (UTC)
• I approve this proposal. RainerU 19:36, 21 January 2011 (UTC)
• I oppose this proposal. --Lebsanbe 19:38, 21 January 2011 (UTC)
• I approve this proposal. User 5359 06:35, 22 January 2011 (UTC)
• I oppose this proposal. --EvanE 08:27, 22 January 2011 (UTC)
• I oppose this proposal. --Frawe 09:54, 22 January 2011 (UTC)
• I oppose this proposal. Believing one could change defaults only by "voting" on the wiki is totally backwards to the way the whole project has been evelving and only leads to broken data/assumptions. Just look at what happened with highway=path. Alv 11:13, 22 January 2011 (UTC)
• I oppose this proposal. --ABRob 12:40, 22 January 2011 (UTC)
• I approve this proposal. -- AndiPersti 15:55, 22 January 2011 (UTC)
• I oppose this proposal. --Computerfreaked 16:13, 22 January 2011 (UTC)
• I approve this proposal. Layer tags are fiddly and make life more difficult for mappers. A renderer that supports easy mapping is a reasonable renderer. --Andrew 16:57, 22 January 2011 (UTC)
• I oppose this proposal. --Aighes 12:24, 23 January 2011 (UTC)
• I oppose this proposal. -- The API should not modify the users data at all, renderers should be free to render bridges as they like, and editors should add a feature to make tagging of this easy if they like to. Basically – fix JOSM, rather than breaking the API to cancel problems out. Beelsebob 12:26, 23 January 2011 (UTC)
• I approve this proposal. --Hobby Navigator 12:39, 23 January 2011 (UTC)
• I approve this proposal. --surveyor54 14:15, 23 January 2011 (UTC)
• I have comments but abstain from voting on this proposal. -- I am unsure what this proposal is about. If it is about defining that "whenever a renderer encounters a bridge without a layer attribute, it should assume layer=1" then this is for the renderer to decide and not for us (or, if you like, for the editor to set an extra layer=* if none is given). This Wiki has no authority to define what renderers or editors should do. If this proposal is about an automated edit in which all bridges/tunnels would receive a layer tag where there is none yet (or about an automated edit where bridges with layer=1 would lose that tag because it is now considered default), then I would certainly revert that edit. --Frederik Ramm 16:54, 23 January 2011 (UTC)
• I approve this proposal. --Foxxi59 18:15, 23 January 2011 (UTC)
• I oppose this proposal. -- Copy Fredrik Ramm. --Gorm 18:21, 23 January 2011 (UTC)
• I oppose this proposal. -- That should be left to be offered as default values in editors --Bielebog 13:09, 24 January 2011 (UTC)
• I oppose this proposal. --Oli-Wan 15:28, 24 January 2011 (UTC)

Voting has ended 2011-01-25. The votes are 37 opposed, 18 approval and 2 indifferent. The result is rejected.