Talk:Tag:junction=roundabout

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Why not junction=mini_roundabout?

Would not the key 'junction' be more appropriate than 'highway' for mini-roundabouts since this tag is only applied at the intersection of two or more ways? Also it would fit in better with junction=roundabout. --Milliams 18:36, 21 August 2007 (BST)

+1 Gorm 02:06, 20 December 2009 (UTC)

Roundabout Names

Is there any facility to add a name to a roundabout -- the main roundabouts here in Basingstoke, UK are named.

Certainly. Add the 'name' tag to the roundabout with the name in it. Morwen 20:45, 27 October 2007 (BST)

Is there any standard / common practice on naming roundabouts in the middle of a longer road? See here: http://www.openstreetmap.org/?way=30877938
==Knossou Avenue====(o)====Knossou Avenue====(o)====Knossou.. etc.
I believe they should have the same name as the bigger road. Zeptomoon 18:07, 1 September 2010 (BST)

As I understood it, the roundabout is a junction and therefore, does not belong to any of the intersecting roads. Consequently it should not carry the name of any road (bigger or smaller). --ALE! 19:49, 1 September 2010 (BST)
The intersection itself might be named, independently and differently from the roads crossing it. For example Prinsenkrysset in Trondheim, Norway. (Intersection of Prinsens Gate and Kongens Gate. If the roundabout is named in such a manner, than name=* is on its place. --Skippern 21:48, 1 September 2010 (BST)
I get the idea! Makes sense to me. I guess, I was tempted to tag for the renderer again...d'oh! Zeptomoon 12:05, 2 September 2010 (BST)
Strong support for this conclusion!--JeffH 21:19, 17 December 2010 (UTC)

Junction Names

A junction does not necessarily have a roundabout and can still have a specific name independent of the road names. For the moemnt I've just put a 'name' tag on the junction. --Le top 09:42, 29 January 2011 (UTC)

The number of points

The example shows some roundabouts and uses "just" 4 points. In the map a typical roundabout has 8 or more points be drawn. It might make sense to add a good hint on how many points are sensible to use (i have seen rounabouts with 30+ points) Flohoff 12:55, 18 May 2008 (UTC)

In my opinion roundabouts should have as many nodes that it takes to give it a round shape. Compare with how you draw a twisty road section. --Erik Lundin 22:53, 17 September 2008 (UTC)
It would be nice if JOSM could create a circle with 12, 16, 24, 32 or 48 evenly spaced points. Alas, it creates paltry 8 points. I have painstakingly (by following, ungluing and rotating) created a 16-pointer which I keep copying and pasting around. T99 (talk) 19:17, 29 December 2013 (UTC)
iD does circles - and squarifies things.
You can add any number of nodes you need to create correct connections with connected streets, notably when there are traffic islands separating the directions, and get the correct shap. On large roundabouts, this helps navigation by more explicitly saying to drivers when to place themselves on the external lane to exit the roundabout. This may be useful also when there are special service lanes (for cycles, buses, tramways, sometimes subways and railways) crossing the central island, which may have the priority to the other vehicules turning around. Just place additional nodes anywhere, then select the ring and press "O" (in JOSM or iD) and all nodes will be aligned on a circle and equally spaced (except onodes for interconnection which will keep their anggular position on the circle.
So you can just start drawing a roundabout using 4 nodes (or 8 nodes if there are trafic islands for separating oneway access/exit ways: place first these connecting nodes. Press O, and a few nodes may be added (this avoids non realistic sharp angles with more than 45 degrees). Add enouch nodes so that segments will not pass through the central island and will keep the direction within the outer lane. Press O again if you have added a few more nodes. Generally with about 16 nodes you get a much better look in all scales (with angles flattened with less than 15 degrees) and this works for most roundabounts. Very large roundabounts may need mode nodes to fit the outer lane correctly. It may also be useful to draw the central island and tag its landuse=* (such as grass) or surface, or other elements on this island (trees, light poles, statue, fountain, sometimes footways...). 8 nodes is generally suitable only for miniroundabouts. 4 nodes is generally insufficient and not realistic as they produce too sharp angles (more than 90 degrees on at least one node).
Note that a some roundabouts are clearly oval, or are half-circular only on two sides, the two other sides being mostly straight; a few ones may be found that are lightly "8-shaped" (often created by interconnecting two successive roundabouts to create a single one, without needing more land space). These unusual shapes are still useful to represent correctly as they provide hints about the direction to take and where/when to exit the ring. In those cases, the fast "O" keyboard shortcut will not work properly.
For these reasons there's no standard number of nodes, the precision needed largely depends on the ratio between the outer and inner radius and the number of generic lanes on the ring (most roundabouts have two lanes, roundabouts with only one lane are normally only mini-roundabouts, whose central island is still traversable by long vehicles such as buses and trucks).
So just place nodes correctly to fit the outer lane of the ring, and correctly place other features you may want to to locate around the roundabout (signals, crossings, postal boxes, recycling containers, bus stops, trafic calming, sometimes even trafic light within the ring itself...) — Verdy_p (talk) 06:56, 29 July 2016 (UTC)

highway=*-tag of a roundabout

Old text said: "If the larger road ends at this roundabout (so all other connecting roads are smaller), the roundabout should probably get the same highway=* tag as the smaller roads."

No, that was not a very good idea.

If a "larger road" ends at a roundabout then there must still be more traffic on any segment of the roundabout (traffic from the larger road plus traffic from the smaller roads) than on either of the directions on the larger road. So, the roundabout should be of the same class as the larger road.

Not necessarily. E.g. the roundabout at the end of a motorway is usually not part of the motorway itself - and is more likely to be something like trunk or primary. I've changed it to "usually". Richard B 16:22, 4 September 2008 (UTC)
Motorways would certainly be the exception - whatever's at the end of a motorway should generally not be tagged as motorway. Similarly, slip roads should be excluded when thinking of the "larger road" - a roundabout where "trunk" meets "primary" should be "trunk", but if it's grade-separated with slip roads the roundabout should be "primary". Such is my opinion, at least. Chriscf 16:30, 4 September 2008 (UTC)

I think the currently documented rule is overtly simplistic. It does not cover all possibilities. For example, what if there are three tertiary highways terminating at the roundabout and one residential highway going through? Obviously, trying to cover all possibilities could make the rule very complex. Therefore, it has to be taken only as a guideline. The mapper will have to use his/her best judgment to evaluate the significance of not only each of the highways but also that of the roundabout. By the way, I think the guideline for roundabouts should be similar to those for links. T99 (talk) 21:46, 29 December 2013 (UTC)

On a relation

I think we need an example for how to tag a relation (e.g tags needed for the ways and tags needed for the relation)--skyper 13:46, 2 November 2009 (UTC)

I see very little use for adding such relation, maybe someone can enlighten us... Surely it's simple to group together consecutive ways tagged with junction=roundabout, before using them for any purposes needing a single entity for each roundabout? Alv 14:08, 2 November 2009 (UTC)

Ideally a roundabout should be a single closed way: you normally don't need to split the closed way even for creating route=* relations. When driving along the route it may happen that you don't take the right turn or can't take it because you've missed it or another vehicle blocked you by driving in the incorrect lane, or where not sure if this was the correct exit; you should not stop in the middle, all you need to do is to make an additional turn, which just takes a few seconds instead of using dangerous moves or stops; making this turn still does not take you out of the route.

But sometimes a roundabout is split in several segments because it has some parts with more or less lanes (e.g. for bicycles) or because some segments are small bridges or tunnels where you need to tag additional protection barriers. When a roundabout is split you may need a relation to tag its inner island and assigning it a landuse, or just to name it and reference it as a single object. A large roundabout in a relation may even be used as an "associatedStreet" holding its own address for houses around it.

In more rare cases, a roundabout will have a special way passing through it for tramways or uses only: these vehicles, when present have the priority to the other vehicles already on the ring (that must give the way): in these cases, there will be warning traffic lights that will turn on when these vehicle are coming. The rest of the time, the special way is closed and this is a normal roundabout. To place the correct trafic lights and conditional giveways, or connect correctly the tram/bus routes, you may need to split the roundabout into sections and group these sections into a common relation.

So there are some valid cases where roundabouts could be relations. And this is already happening. However for most roundabouts (small enough for the central island containing nothing more than a handful trees or a light or some flowers), they should not be split at all and the central island should be traced separately using a concentric way. — Verdy_p (talk) 01:14, 22 March 2017 (UTC)

It seems there is a mixup in your arguments of roundabouts as a member of a relation, and junction as a relation. I have not yet investigated what type the 900 mapped relations are. Sure a roundabout can be a member of a route. Not so sure what purpose a relation would have that combines the highway with the inner green landuse. associatedStreet is used by very few mappers nowadays as we have a functional addr:* scheme. For the traffic functionality, there is no relation needed; routing engines cope well with recognising the closed loop tagged with juntion=roundabout, even when the loop is split for different lane features. My conclusion, on relation = no.--Polarbear w (talk) 10:33, 22 March 2017 (UTC)
You seem to misread, I was only speaking about using junction=roundabout as relations. For cases where a roundabout is split in multiple segments these relations are in fact intended to describe what is within the island, and I think it's just better to draw a separate circle for this inner use. But for creating ROUTE relations, I've never said we need to add roundabout relations as members of these routes; however, adding multiple ways taken as part of the roundabout just complicates route relations: it is not justified for something else than creating bridge or tunnel sections in the roundabout. For all other case, a single closed way can be tagged and we evidently don't need a relation for the roundabout itself, and not even for routes passing through them when we can just include include the single closed way as a single member for the route relation.
There's still another need you forget: roundabouts are more than just highways and are used as "places" with their own name, and their own address: this requires a relation, but NOT for the junction itself, only for a "associatedstreet" relation to associate the closed way (or the list of ways) as members (with role "street") and addresses around it also as members (with role "house"): this type of relation however should not be tagged with junction=roundabout which only concerns the highway part (and not anything that may be present in the central island). There exists also cases where these "associatedstreet" relations will also need to include shortcut ways passing through the roundabout (at level or in tunnels), or on the side of it: these ways do not stritcly belong to the streets they connect, but they may be the effective highways where the address points are located (with possibly junctions with private access alleys); these also concern footways or cycleways which are part of the addresses located there as they are the effective ways to access these addresses (inaccessible directly from the loop of the roundabout junction).
When roundabouts are used as places these shound be delimited as a standard multipolygon area, not delimited by the highways but drawn on the limits between the public area containing highways/cycleways/footways and the central island and everything inside of it) and the bordering private properties or amenities (public buildings, parks, sports centers, theaters...): these polygons could be landuse=residential polygons; they'll have a name and a place=* tag, such as place=square (that polygon does not have to be circular, and most often it won't be, even of the roundabout inside it is circular, but as well it should not be used as an associatedStreet relation for grouping addresses located around it, but still located outside of it) — Verdy_p (talk) 16:34, 23 March 2017 (UTC)

I analysed a couple of examples where junction=roundabout was used on a relation:

  • type=multipolygon used to create an area:highway with the middle green cut out. Multipolygon use is not considered a relation tag.
  • type=multipolygon containing highway segments as members. Tagging mistake (leading to area rendering in Carto). Fixed where found.
  • type=route used to attach a nameless route just over the highways (already tagged junction=roundabout) forming the roundabout. this is completely useless, as routers already recognise the closed loop with one or multiple ways. In some of these route-roundabouts the highways lack the junction=roundabout and are consequently not recognised by popular routers. Some mappers add route=junction
  • type=junction which is only a proposed type (itself used 1100 times); the proposal mentions junction=roundabout as one of its categories. Some of these relations carry just one members, which makes them pointless.

I still conclude there is no current valid reason to keep the OnRelation flag. --Polarbear w (talk) 19:07, 22 March 2017 (UTC)

ref tag

Is it correct to remove ref tags from roundabouts? I personally think that this is ok as a roundabout is a junction and therefore belongs to two or more different roads. But please correct my reasoning if I am wrong. I want to get a second opinion on this. --ALE! 22:24, 3 January 2010 (UTC)

Is the highways parts of relations? In that case the ref is protected by the various highway relations, and not really needed on each road segment. If not, than maybe all the road refs should be included. But what about roads that starts or ends in a roundabout, should their refs be extended to the roundabout, or is this really only valid for roads crossing a roundabout? I tend to tag only the refs of roads passing the roundabout. --Skippern 08:43, 4 January 2010 (UTC)
I think the situation is analogous to the 'Roundabout names' issue discussed earlier: the roundabout does not belong to any of the roads and should therefore not have road refs on it. To be more concrete: if you're crossing a roundabout from one minor road to another, it just causes confusion to be told that you have to drive some metres on say a primary road with such and such number. And IMHO, adding refs from all classified roads would be just like including all the road names, just leading to even higher levels of confusion! However, as with names, if a country gives numbers to roundabouts themselves, then these can of course be tagged. I strongly agree with ALE, who started this topic, but I see a lot of misleading tagging here so it would be really good to get some clear guidance into the wiki itself. --JeffH 21:19, 17 December 2010 (UTC)
I guess it varies from country to country. F.ex in Norway, an intersection (no matter if its a roundabout or not) is usually funded, named, owned and maintained by the same agency/department as the road 'highest' class of two roads crossing. In those cases, using the same ref=* on a roundabout as the "master road" would be quite correct. --Gorm 19:55, 4 June 2012 (BST)
The ref= should be handled analog to the name. It is not uncommon in the world that roundabouts have a given name and ref. As per definition the roundabout is a junction e.g. interconnects multiple streets. So it is per definition not exclusive part of one of the streets so it should not carry the name or ref of one of the connected streets. Flohoff (talk) 18:03, 7 November 2014 (UTC)

Two editors confused by roundabout instructions

Just a suggestion for improving this article. I was mapping my first roundabout today, and I wasn't sure whether the following applied to the roundabout I was working on:

If a road is split into two separated carriageways (one approaching, one departing), draw those explicitly and tag these carriageways (not the roundabout) with oneway=yes. Pay attention to their correct orientation and use separate nodes of the roundabout for the approaching and departing road.

Does this apply to all roundabouts that connect to two-way streets? What does this look like in practice? I decided to just connect the normal residential roads to the roundabout circle that I'd made, and not split anything, but I don't know if I did the right thing. And then later today, another editor asked a related question on IRC: "If a highway approaches a turnabout junction, do we split the way into two oneways? And if we do it, how to add both the oneways in a relation so that continuity (in the relation) is preserved?"

Since both of us were confused, it sounds like this page could be improved with an example or other additional explanation for that section. Also, the other editor and I were both unfamiliar with the term "carriageway"; we had to look it up while reading this page. Thanks! Brittag (talk) 05:52, 1 September 2013 (UTC)

I believe the intent here is that this applies where there is a significant island, or other protected area, between the two carriageway, i.e. they are physically separated. Although some people like to micromap everything, I think that an ordinary residential road is best mapped as a single way. -- Hadw (talk) 14:22, 17 November 2013 (UTC)

Bypass lanes for nearside turns

I've come across a roundabout where at least some of the exits have a left (nearside) lane that has priority over traffic on the roundabout for traffic that is leaving at the next exit. That breaks the normal UK rule that traffic on the roudabout has priority. I'm not convinced that the right approach is to split that lane off before the roundabout, as lane changes to or from it are possible along its whole length, and tend to be the only safe approach for bicycles. -- Hadw (talk) 14:13, 17 November 2013 (UTC)

On further reading, it turns out the real problem here is that this is actually a traffic circle and not a roundabout! -- Hadw (talk) 15:10, 17 November 2013 (UTC)

Tag:junction=traffic_circle should be explicit

The article currently says that traffic circles should not be tagged at all. However, it seems that people expect satellite navigators to tell them to turn off at the nth exit, but satellite navigators aren't clever enough to infer that a feature is a traffic circle and therefore has exits. This, combined with a general failure to read and understand the section on what is not a roundabout, is almost certainly resulting in mis-tagging of traffic circles as roundabouts. -- Hadw (talk) 11:54, 5 January 2014 (UTC)

this has been sorted with the introduction of junction=circular after discussion on the tagging list. junction=traffic_circle is ambiguous and could easily be confused with regular roundabouts. --Polarbear w (talk) 17:06, 24 November 2016 (UTC)

Circular and widened road features vs Tag:junction=roundabout

There overlapping content, is there option to cleanup pages in less duplicate manner? Xxzme (talk) 18:29, 10 November 2014 (UTC)

The "Circular and widened road features" were written as a template that had been embedded in the pages of the different tags involved.--Polarbear w (talk) 17:06, 24 November 2016 (UTC)

On a node?

The definition allows junction=roundabout on a node, which makes no sense to me, it could always be drawn as a way. The node should be reserved for the mini_roundabout case. Currently it is used 4000 times, however that is less than 1% of the 450000 tags on ways.--Polarbear w (talk) 21 March 2017

Isn't it same logic as allowing a building on a node? If you are in a hurry or you focus on something else while mapping, you can just tag it on node and later you or someone else might return to it and map it properly. Chrabros (talk) 00:01, 22 March 2017 (UTC)
The nodes tagges are possibly mini-roundabouts, but most often, people don't want to take the time to draw a real circle and reconnect the ways (without breaking bus routes at the same time) It's just so simple for them to just mark a node: it is probably OK if it's with a FIXME to allow others making the geometric changes, but in my opinion they should just add a FIXME. A junction=roundabout by itself has no meaning except with lots of default assumptions.
  • Sometimes this is because they know there's a roundabout, but it's still not visible on the imagery and instead of creating an approximative form for ways, they just tag a node, knowing that this will be detected for later review. Notably the position of crossings for footways, the rection of ways by traffic islands, the exact measurement of the central island, the number of ways in the ring, or if cycleways are interrupted, or of bus stops are moved: they don't know how to place these details.
  • Sometimes this also happens only for juctions created temporarily during works nearby. This won't be on aerial photos when the works will be finished, and it's not very easy to draw these from photos taken from the ground.
If the junction is new or has been recently changed, tagging the node only is just an interim solution that is best then nothing, as if it was still a standard crossroads.
More and more roundabouts are being built worldwide to replace standard junctions: they replace standard crossings, by removing trafic lights, reducing accidents because they are also efficient speed limiters, they are still making circulation more fluid, reduce the noise and pollution, they allow planting trees, reduce the bad effects of winds on long boulevards, they are decorative, and don't use any energy for traffic lights. They're a bit e'xpensive at construction time, but then municipalitites save money each year. And driver's life is simpler: they only need to look for vehicles from a single direction, and spend less energy by burning fuel waiting in long lanes of vehicles near traffic lights or in trafic jams that pollute everybody around. Only US still does not have a lot or roundabouts, but now they are spreading worldwide (even if European countries have many more, you can find them including in African cities or in China). US has a few ones but only for very large roundabouts, or for roundabouts with sections passing through bridges above uninterrupted motorways. — Verdy_p (talk) 00:43, 22 March 2017 (UTC)

Thanks Verdy_p for the favourable speech for roundabouts, that is correct, but we are discussing the drawing style. Even for a new roundabout, all you need to do is drive the full circle with your GNSS, and you can map it precisely even without aerial imagery. Thus this is no reason for me to draw a node only.--Polarbear w (talk) 10:21, 22 March 2017 (UTC)

I agree that this tag should not be used on a node - either it's a mini_roundabout node when flat or a junction=roundabout way when it has a non-traversable island. Though as has been mentioned, some mappers might use it as a placeholder - would be good if QA tools like keepright or Osmose highlighted it as requiring fixing. GinaroZ (talk) 16:08, 22 March 2017 (UTC)
Osmose already signals incorrect roundabouts (including those that are traced in the incorrect direction, and it also detects circular oneway highways that should be roundabouts; it also signals names or references given to them to match only one of the roads/streets connecting to them: roundabouts normally have no reference or their own reference, and have no name or use their own name distinct from the public roads/streets connecting to them; The rules about these are country dependant and may be tuned per country). — Verdy_p (talk) 18:57, 22 March 2017 (UTC)
Users should be careful then verifying Osmose flags, since not every circular oneway is a roundabout. --Polarbear w (talk) 17:06, 24 November 2016 (UTC)
Yes but in almost all cases, Osmose detections are correct. If this is not the case we should be able to tag these explicitly with another value for junction=*, probably like juction=crossroad, or with an explicit note=* affirming it. These cases are almost inexistant in France, and Osmose detects the case where the circular way has only one connection for motorvehicles: this is efecetly not a roundabout but an "internal loop": a goosd sign is these cases have parking lots around the end, while stopping or parking is normally forbidden around roundabouts.
Note that a roundabout is still a roundabout if there are multiple connecting cycleways, we can only ignore the footways and service ways for alleys to private properties
But beware that real roundabouts also exist within private areas with public access (e.g. in commercial centers between parkings separated by trafic islands or other barriers or footways).
Roundabouts are also not necessarily purely circular, they exist with square shares, or ovals, or were created by joining two touching toundabouts in an 8-shaped loop and closing traffic on their touching borders. — Verdy_p (talk) 19:39, 22 March 2017 (UTC)