[Talk-us] Relations, cycle routes

[stevea]

>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