On 02/03/2011 02:25 PM, PJ Houser wrote:
Hi all,
I have some basic questions:
> 1) Why are relations preferred for bike routes?
Take a look at Santa Cruz County, California with
OSM Cycle Map layer (see the text in the last
paragraph at
http://wiki.openstreetmap.org/wiki/Santa_Cruz_County,_California#Work_to_be_done_in_the_County).
We tag highways (AGAIN: additionally tag the WAY
containing highway=*) that the County (Regional
Transportation Commission) displays on its
annually-published paper Bike Map thusly:
Class I: "highway=cycleway"
Class II: "cycleway=lane"
Class III: "bicycle=yes"
With these tags as/added to a highway=* way,
OSM's Cycle Map layer renders, respectively, dark
blue stitches (I), dark blue casings (II), and
brown casings (III). This seems 100% unambiguous
to everybody so far I have spoken with:
renderings "match" except in color, but
logically, yes, 100% matching with how the County
publishes its annual paper map for these three
Classes of bike ways / cycle ways / what we as
cyclists ride on. Call this "Part One." No
numbered routes, just bike INFRASTRUCTURE as it
exists today.
ADDITIONALLY, there is a "local cycleway network"
route numbering system being simultaneously
proposed. The local jurisdictions are in the
process of literally seeing proposals in OSM, as
we speak, using a two-digit (initially, to
include a third digit on spur and belt routes)
numbering space, but only on "major" (0, 5)
routes first, 8 and 80 being the local examples
of the first two "spine" routes created. Because
there is a tag "state=proposed" which is exactly
right for these, AND it causes "dashing" to imply
"proposed," we use it.
So, starting from scratch as a routing network is
developed (it is truly helpful to have the Part
One, as above, describing the EXISTING cycleway
infrastructure already tagged in OSM...TAG the
HIGHWAYS), a new relation is created with these
tags:
network=lcn
ref=8
route=bicycle
state=proposed
type=route
Then, each segment of highway which is actually a
member of the route is added as a member to the
relation (in order of connectivity). Voilá.
Looks good. It sounds harder than it is. Call
this "Part Two A."
When a route is "approved" by the local
jurisdiction (city, town, county) just remove the
"state=proposed" tag and the "dashing" goes to
solid. Call this "Part Two B."
Get it? There are two independent (but related)
things going on: the highway tags describe the
actual infrastructure (Class I, II and III
bikeways) and the relations describe the route
numbering system that "lies on top of" this.
Then there's rendering.
Yes, there is! Use the above to potentially use
OSM as a public planning tool to discuss bicycle
routes. It's what we are doing, and it is very
handy (a laptop with wireless and a video cable
feeding a monitor for a viewing audience works
well). Note: Cycle Map layer renders about once
a week, usually around Wednesday/Thursday.
May OSM bloom with (properly constructed, public
consensus or de facto approved) bicycle (route)
networks!
stevea
California
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