|Proposal status:||Draft (under way)|
- May have different rules (eg lane priority, driver responsibility in crash)
- Provides a simpler initial alternative to setting up type=connectivity, or drawing separate lines in case of raised turbo-roundabout lane dividers. (not a replacement for turn:lanes=* on approach)
- Potentially ease router navigation around more complicates settings (eg very closed spaced pairs)
- Prevents renderers and editors from circularizing shapes that are not circles
- Renderers may cluster roundabout icons more accurately and reliably (?)
- roundabout=single (default)
- roundabout=double: next to each other, treated as single location
- roundabout=dumbbell: Separated far enough by usually an overpass/underpass, treated as two locations like a diamond interchange
- roundabout=turbo: Center island must have cut-out corners in the turbo block concept. Markings only is lane_markings=spiral (see below). (TBD: Any conflicting case of double turbo-roundabout?) May be used together with separation:lanes=*.
- roundabout=ring: Ring junction / magic roundabout
(TBD: magic roundabout)
For multi-lane roundabouts.
- lane_markings=* (reused)
- lane_markings=concentric (default?)
- lane_markings=partial_concentric https://www.researchgate.net/profile/Ezenwa-Amanamba/publication/303859453/figure/fig2/AS:370912374345730@1465443809880/Concentric-Markings-DfT-1997-B-Partial-concentric-markings-These-also-are-circular.png
- lane_markings=concentric-spiral https://www.researchgate.net/profile/Ezenwa-Amanamba/publication/303859453/figure/fig3/AS:370912374345731@1465443809909/Partially-concentric-markings-DfT-1997-C-Concentric-Spiral-Alberta-markings-This.png
- lane_markings=spiral https://www.researchgate.net/profile/Ezenwa-Amanamba/publication/303859453/figure/fig4/AS:370912374345732@1465443809951/Concentric-Spiral-Alberta-markings-DfT-1997-D-Spiral-markings-This-system-is-best.png
When different markings are mixed, split the sections to tag accordingly.
(TA 78/97) CD 116 Appendix D: https://www.standardsforhighways.co.uk/prod/attachments/2b5901c6-3477-4826-b780-cf99003fb5e0
- roundabout:shape=circle (default)
- roundabout:shape=oval: Common on single roundabout interchanges, or non-standard junctions.
- roundabout:shape=dogbone (aka raindrop). Stretched out to both sides, while having only one loop
- roundabout:shape=square: Only use this if it fits junction=roundabout definition's priority rules
Turning circles and loops
- turning_loop=* : Counterpart for shape of highway=turning_loop or the separately drawn highway=* road (some turning_circle=* are likely inapplicable)
Please comment on the discussion page.