[Tagging] Roles of route members (was: Merging tagging scheme on wiki pages of Hiking, ...)

Volker Schmidt voschix at gmail.com
Sat Aug 17 12:40:15 UTC 2019


The sequence of the component ways in a walking/hiking route relation is
irrelevant for a hiker who use a navigation device to walk along the route.
Why?
How do you walk a walking route with a navigation device?
Basically you have two options:
A) you have prepared beforehand a GPX track, typically by using a
routing/planning tool on a web site. That site does off-line routing for
you. During the walk you follow the GPX track on the display of your GPS
device (you keep you position on the track on that you see on the screen)
B) you use an equivalent navigation process as in (A) but you execute it in
real time on the map that you have loaded on your navigation device.

In both cases you use some kind of algorithm that finds for you a (nearly)
optimal route from waypoint to waypoint. What does the routing algorithm
do? It assigns, from a table that defines your means of transportation,
"cost" (or "penalty") per meter to each way on the map and basically finds
the "cheapest" connection between consecutive waypoints (in the simplest
case there are two waypoints: start and destination for the off-line
navigation, and actual position and final destination for the on-line
version).
The cost for each way type is dependent on your means of transport.
In the case of walking the cost for a motorway will be near infinity, with
the effect that a hiker will not be routed via a motorway. A perfectly
smooth footway will have a very low cost, a bumpy footway will have a
bumpiness penalty (you are forced to walk slower) and so on.
How are hiking route relations handled? The fact that a specific way is
part of a hiking route relation means that it gets a cost benefit with
respect to an equivalent way that is not part of it. In this way the
algorithm gives preference to those ways that are part of a walking route
relation. I's up to designer of the routing cost table, how much advantage
she will give to a given type of route; she may want to give a national
hiking route a bigger cost advantage in comparison to a local hiking route.

This is the basics why the routing  algorithm does not "care" at all about
the sequence of the ways in the hiking route relation.


On Sat, 17 Aug 2019 at 13:08, Peter Elderson <pelderson at gmail.com> wrote:

>
>
> Op za 17 aug. 2019 om 12:31 schreef Andy Townsend <ajt1047 at gmail.com>:
>
>> > but I would like to see one make a plausible navigation route out of
>> the E2 Yorkshire relation as it is now.
>>
>> Where are you going from and where are you going to?  Without that
>> information "make a plausible navigation route out of the E2 Yorkshire
>> relation" makes no sense.
>>
>> That's exactly the point why you can't use a walking route relation as a
> navigational route, unless it has been carefully prepared to be an ordered,
> uninterrupted single-chained A2B route.
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