NOTICE: help.openstreetmap.org is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum

# Best Practice for Super Relations

 1 Dear All, I am in the process of splitting a large relation (previously 523 members and I understand 300 is the maximum recommended) into a super relation made up of two children. The relation describes a ring road which has twin one-way ways throughout its route. I propose to have one child with all members in the role of "forward" (clockwise righthand carriageway) and another as "backward" (anticlockwise lefthand carriageway). I understand the mechanics of how to do this with JOSM but the question is, what is best practice for the order of the "backward" child? As a trivial example, if the first four members of "forward" are A, B, C, D, should "backward" have the same order or should it be reversed i.e. D, C, B, A? Many thanks in advance, Feilipu asked 12 Apr '13, 00:06 Feilipu 90●2●3●9 accept rate: 10% 1 A link to the actual relation might help here, so that people can see the way direction on each carriageway among other things. (12 Apr '13, 00:56) SomeoneElse ♦

 1 It should be forward and forward, otherwise the anticlockwise left-hand carriageway would be going backwards - Cars don't drive backwards! The first four members, or the order of each child, should be according to the customary direction of the ways, and the roles of the children relations should both be "forward", hence: A--->B--->C--->D D--->C--->B--->A Where letters represent junctions they pass through. A backwards relation would only be necessary if the route was entirely two-way. Of course a motorway isn't usually two way in the UK. The only one that was a single carriageway that was (A6144(M)) was downgraded some time ago. answered 12 Apr '13, 00:09 Amaroussi 141●4●5●11 accept rate: 0% Thanks for the quick reponse but traffic is flowing in opposite directions - there is no question of cars driving backwards. D<---C<---B<---A D--->C--->B--->A (12 Apr '13, 00:20) Feilipu Is it a dual carriageway or single? The order for anti clockwise dual carriageways should be DCBA and the role generally forward for the customary direction of the one-way route. Sorry for the hurry but I am nearly going to bed. (12 Apr '13, 00:21) Amaroussi It is a motorway in both directions (12 Apr '13, 00:28) Feilipu The first four members, or the order of each child, should be according to the customary direction of the ways, and the roles of the children relations should both be "forward", hence: A--->B--->C--->D D--->C--->B--->A Where letters represent junctions they pass through. (12 Apr '13, 00:35) Amaroussi OK, seems logical. I thought that a backward relation might be used by route finding apps etc. Is it superfluous in this case? (12 Apr '13, 01:30) Feilipu A backwards relation would only be necessary if the route was entirely two-way. Of course a motorway isn't usually two way in the UK. The only one that was a single carriageway that was (A6144(M)) was downgraded some time ago. (12 Apr '13, 01:51) Amaroussi Thanks Amaroussi, I'm clear now. (12 Apr '13, 02:16) Feilipu @Amaroussi - isn't there still the A601(M)? (12 Apr '13, 11:05) Richard ♦ showing 5 of 8 show 3 more comments

By Email:

Markdown Basics

• *italic* or _italic_
• **bold** or __bold__
• image?![alt text](/path/img.jpg "title")
• numbered list: 1. Foo 2. Bar
• to add a line break simply add two spaces to where you would like the new line to be.
• basic HTML tags are also supported

Question tags:

×236
×7

question asked: 12 Apr '13, 00:06

question was seen: 2,726 times

last updated: 12 Apr '13, 13:26

### Related questions

NOTICE: help.openstreetmap.org is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum