[OSM-talk] Cycleways wiki doc enhanced

[Lester Caine]

Steve Bennett wrote:
> On Mon, Jan 4, 2010 at 3:08 PM, Claus Hindsgaul 
> <claus.hindsgaul at gmail.com <mailto:claus.hindsgaul at gmail.com>> wrote:
> 
>     Just rewind a bit; in the start of this thread, I cited a guideline
>     developed on talk-dk to aid the choice between separate and tagged
>     cycle-tracks/lanes on a street with the aim of getting the best map
>     description in the end. In the following discussions, I have tried
>     to outline why this guideline did not end up saying: "always
>     micromap everything".
> 
> Yes, many of these discussions seem to devolve quickly into battles 
> between the "map everything in minute detail" and "exercise a bit of 
> discretion" camps. Then the two camps look at each other, realise that 
> it doesn't matter what the other camp thinks, and goes back to doing 
> whatever they want. It's one problem with mapping in general - if I'm 
> the only one mapping my town, I can pretty much do whatever I want, 
> because no one else is ever going to bother to look, or comment, or 
> change it.

That probably sums it up nicely ;)

The problem at the end of the day is that the different levels of 'complexity' 
have to co-exist, so there HAVE to be some RULES. Existing 'routes' that are 
already mapped with a single 'complexly tagged' way should have the potential to 
be mapped as areas at some point in time. The problem is striking the correct 
balance between additional tags and an additional way, but with an understanding 
that a group of ways may be viewed as a single way at a higher zoom level. Width 
tags only really work on a single track, since the 'center line' requires 
symmetric structures. Adding tags to provide an 'offset' from a structure ( 
footway on left, cycleway on right and the like ) then require a lot more 
'mapping' work over simply adding a footpath way interwoven with the vehicle 
way. In the case of structures that I would LIKE to map in my local area, 
footway and cycleway tracks form a lot more complex structure that personally I 
do not plan to map as 'offsets' from the existing vehicleway. AND the fact that 
there is no consensus on TAGS for ADDING that data prevents it happening that 
way anyway. :(

As I have said all along. The different levels of complexity must co-exist and 
so a high level view must be able to combine data from the lower level and 
ignore any unnecessary complexity for that view. Arguments about 'routing' and 
the like do need to consider if the fine detail is necessary to accurately 
provide directions. In my one simple local case such directions as 'cross road 
and continue on the other side' are needed for pedestrian routing, but not 
vehicle. On a busy London road, where railings and pedestrian/cycle crossings 
are provided that fine detail DOES result in different ways for foot/cycle 
traffic over the cars. The same 'debate' applies to lanes on the road system, 
with routing direction able to pick up such things as 'get into inside lane and 
take slip road'. Again heavily populated areas will have separate 'ways' for 
pedestrians, cycles and cars, and while a dual carriageway through a town can be 
mapped as a single way with central reservation with fence, cyclelane left and 
right, footpath left and right all indicated with tags, that is just a very low 
zoom view. Moving in closer, and even for simple car routing at the higher 
level, two carriageways make more sense, and then you have to 'offset' which 
side has the other ways ... and start taking account of where cycles and people 
can cross to the other side.

The problem is NOT at which level do you switch between on or other 'tagging 
style', but rather how do you combine the information from a lower view which 
shows the fine detail which is REQUIRED at that level into the higher level views?

Claus - It's not a simple matter of 'aiding the choice between' - the more 
fundamental problem is how do we get both to co exist? If someone is going to 
DICTATE that we will never map some details then I think we have a problem? But 
that is where we are stuck at the moment anyway?

-- 
Lester Caine - G8HFL
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