User talk:Bicycle tourer/Junctions

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Overall summary

Todays OSM-wiki page about junctions jumps directly into intersections, while missing to give an overview about different types of junctions (like T-junctions, Y-junctions, 3-way junctions, same grade intersections, multigrade intersections, triangular junctions, roundabouts etc. etc). Furthermore only some of those types are explained in more details in separate pages (like roundabouts).

Background

Why a new page in parralel to the existing one

It would be extremly difficult to change the existing junctions page step by step while many readers are still using it the best way it is currently usable. It is esp. difficult because the different special pages for subcases (like confluences, 3-way junctions) have to be built and approved before they can go into production, but they are difficult to be understood for approvers if they have no idea how it fits into the overall picture, given by the (changed) junctions page. Therefore a new version of the junctions page has to be built in parallel to the existing one.

Why is this proposal located in user pages

It's similar to the proposed confluences page: The official way for a feature-proposal would be to generate a new wiki page under "proposed". But several things are different:

• This is not a proposal for a new feature (tag) in just one single page.
• The proposal has impact on existing pages, it suggests to change existing pages. So if this impact should be made visible earlier, the existing pages have to be copied somewhere else (my user pages) and adapted here

So to avoid changes in existing Wiki pages I created everything in my user pages as sub pages. Of course if the proposal is agreed and chosen, everything has to be moved into the official parts of OSM wiki.

But to give advise how to map a junction it must be known which type it is. for giving rules about how to classify parts of junctions it is important to clarify first which of type a certain junctions is, has to be mapped and then explain the different types in separate pages to avoid a monsterpage for junctions. To accomplish this content of todays junctions page has to be moved to a special page about intersections, while more information about the different types has to be provided (including links and examples).

This page was generated There are many different ways how roads/streets can cross, merge, split or connect. This OSM-Wiki page gives an overview of the different junction types, rules to decide which type of junction should be applied, links to pages with more precise descriptions and examples for types of junctions.

a certain junction might be The rules how to classify highway links (primary, secondary etc.) do not lead to useful results if one road merges into another (confluence). The existing comprehensive list for different classifications of involved roads misses a distinction of different types of junctions and therefore produces wrong results for certain types of junctions (like a confluence). Inserting such a distinction (including criteria) into the wiki page for highway links would create a monster page (the confluence case alone leads to reference pages of certain size, which are separated from the confluence page). To solve the problem of bad rules and defining the right rules for confluences, several things have to be done in parallel, which is the content of this proposal, including suggestions for appropriate wiki pages:

• Introduction of classification of different types of junctions like intersections, confluences, roundabouts etc. (tbd in a new page for junctions, no suggestion yet available)
• Introduction of confluences (German "Einmündung") for places, where one road merges into another one (Main page to this talk page)
• Types of confluences (here is the proposed reference page)
• Rules how to classify links in case of confluences (see this proposed reference table)
• Rules how to classify links in other cases (as an extension to the existing page about highway links, tbd after acceptance of the above)

Expected result after acceptance

After deploying this, esp. after making the classification rules more specific to the different cases (this proposal focuses on confluences), there is a good chance that a real consensus is achieved about these rules (hopefully visible by vanishment of heated discussions/islands of private rules/resignation of mappers) and people know how to map and classify highway links in different cases (at least they know where to look at).

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Open issues

• Explanation of history of links (first motorway/trunk only, then extension to any junction, not looking enough at the rules)
• Types of junctions: motorway exit, trunkexit, confluence wiht road

What to achieve

Was wir brauchen sind Regeln bzw. Empfehlungen (written by forum member Mammi71): - wann nehme ich _link oder kein link - bei unterschiedlichen highway=* die höhere oder niedrigere Kategorie - wohin kommt welches ref bzw. destination:ref