User:Bielawski/Sandbox/Sign proposal

General-purpose signs
Proposal status:	Draft (under way)
Proposed by:	Bielawski
Tagging:	*=*
Applies to:
Definition:	*
Statistics:
Rendered as:	n/a
Draft started:	2009-06-02
RFC start:	FIXME
Vote start:	*
Vote end:	*

Proposal

This proposal is to describe the exact signs used to direct traffic so that routing software can give more accurate instructions and show previews of signs. The idea of describing signs is ripped off from Cohan's proposal

Rationale

When using a routing software as navigational aid, it is very helpful to be shown the signs to follow. E.g. instead of just saying "Make a slight right at exit 1" a routing software also could say "Follow the sign to route 342 east toward Pointe-Fortune (exit 1)" and show an approximation of how the sign will look.

Setup

The basic thing that sets this proposal apart from the previous one by User:Cohan is that it supports more information on the sign than a destination. Each type of sign (by type I mean something specific, e. g. a sign in Texas denoting an exit to a US highway that shows it as the route to two towns and an airport) has a memberless template relation that contains both a textual description of the sign type and a SVG representation, both including fields that will be filled in by the relations representing the actual signs.

The sign relations are similar to the ones proposed previously, except that they have as a member a template relation as described above and have tags corresponding to the fields in the template.

Tagging: template relation

Tags

Key	Value	Example	Comment
type	sign_template	sign_template
svg	URL to an SVG image (preferably hosted by OSM) representing an example of the sign.	http://wiki.openstreetmap.org/images/c/c1/Sign_ca_on_exit_1cr_2sn_dest.svg	In the sign image, fields are marked using $(FIELD_NAME).
text:en	Textual description of the sign, including fields	Road $(ref:road) – $(name:left) to $(city:left) and $(name:right) to $(city:right) (Exit $(ref:exit))	One tag per language

Tagging: sign relation

Tags

The tags for this relation correspond to the fields defined in the template relation. For example:

Key	Value
ref:exit	336
ref:road	1
name:left	Mississauga Road
Et cetera...

Members

Way or Node	Role	Recurrence?	Comment
	sign	exactly one	The point where the sign is. This could be an intersection or a point before it. In the example this is [Node B].
	to	exactly one	[Node C/Way W] A (the first) way/node on the way after the junction
	from	optional	[Node A/Way Q] A (the last) node/way before coming to the junction. Unnecessary when destination signs are the same from both directions. (D-B-C = A-B-C)
	via	optional	[Node B] The node where the roads cross
	template	exactly one	The template that the sign uses.

Example

Lets say I'm approaching the crossing in the photo on the top of this page and the routing software says that I should turn left. It would be an additional aid to know that I want to follow the sign to Österstad. This aid becomes increasingly helpful when following a larger road with many exits or crossing ways.

The relations for the signs in the picture: (Assuming that the signs are not visible from the Åsmestad road.)

<relation id="??">
  <tag k="type" v="destinationSign" />
  <tag k="destination" v="ÖSTERSTAD" />
  <tag k="colour:back" v="blue" />
  <tag k="colour:arrow" v="white" />
  <tag k="colour:text" v="white" />
  <member type="node" ref="B" role="sign" />
  <member type="way" ref="W" role="to" />
  <member type="way" ref="Q" role="from" />
</relation>

<relation id="??">
  <tag k="type" v="destinationSign" />
  <tag k="destination" v="Åsmestad" />
  <tag k="colour:back" v="yellow" />
  <tag k="colour:arrow" v="red" />
  <tag k="colour:text" v="black" />
  <member type="node" ref="B" role="sign" />
  <member type="node" ref="D" role="to" />
  <member type="way" ref="Q" role="from" />
</relation>

Questions to be ironed out

• How to do when more than one sign is pointing in the same direction. One relation for each sign (destination) or can this be managed within one relation? Only entering one (the topmost) sign?
• Should caps be used if used on sign? In Sweden, as the example photo shows, destinations along major roads are written in caps while destinations along minor roads are not.
• Sometimes an icon is used as destination, especially for airports. How to handle this? Special strings like {AP} and let the routing software show a proper icon instead?
• Signs specifying a destination and a road number, e.g. E4 Umeå. The road number might have different colours than the rest of the sign.
• Signs not specifying a destination, only a road number.

See also

• Proposed_features/Guidepost

Discussion

Discussion on the Talk page