Mini_roundabout

General talk
61

That is probably why we don’t bother with mini-roundabouts: people would still not go around each other in this situation. The dot in the middle would simply be ignored. We do have small roundabouts, where traffic barely has to move to pass it straight-on, but the centre island (no truck apron, just kerb) always has signpoles with a roundabout traffic sign facing the approaches, and all allowed traffic has to pass that on the correct side according to the oneway arrows of the sign. So in fact: no oneway arrow sign, no roundabout.
And, we never have automatic priority on the junction. So in fact: no give-way signs, no special priority, just the default priority for the righthand side.

For road designers this means: if you can’t put a roundabout sign in the dot, because some vehicles need the space to pass the junction, you either ban those vehicles from the roads involved, or you simply can 't have a roundabout there.

Which, for OSM, means: it’s junction=roundabout only if there are giveway signs on all approaches AND roundabout signs in the middle, face clearly visible from all approaches.

Announcement signs in NL will graphically show the upcoming roundabout, but do not give it any legal status. So the sign showing the layout of the Swindon Magical Roundabout would not be enough; in NL, each of the mini-roundabouts would have to have its own roundabout sign. Which in fact in Swindon is sort of arranged by the large arrows on the surface. I don’t know if those arrows have any legal status, but they do get the message across. So I think OSM could map these access roundabouts as junction=roundabout.

Then again, probably, our OSM based navigation would announce “go right on the roundabout, third exit” which would make no sense to the driver, who thinks that the whole square is the roundabout and that the navigation should say “first exit”. Which explains the idea to have no roundabout tagging at all at the Magical Roundabout, and just get the connectivity right with correct oneway and priority tagging, while staying as close to the actual geometry as possible.

62

I think this improves the interpretation for the joining roads, but to me the middle ring is incorrect. IMO the existing segments for the CCW ring need to be joined to the roundabouts and the additional links removed as there is no island forcing a separation and as far as I can tell the road markings both mean “give way to roundabout traffic”:

Give way to traffic from the right at a roundabout | 967x420 ,25%
Give way to traffic from the right at a roundabout | 967x420 ,25%967×420 12.1 KB

Give way to traffic from the right at a roundabout

Give way to traffic from the right at a mini-roundabout | 967x420 ,25%
Give way to traffic from the right at a mini-roundabout | 967x420 ,25%967×420 13.7 KB

Give way to traffic from the right at a mini-roundabout

Edit: Doesn’t look too bad with oval-abouts?
image

1 Like
63

This version is not correct I’m afraid. But the problem is not with mini roundabouts, but with the large central island. The are a lot of fictional segments in the middle now, but there are no barriers there! It is a difficult one, but there is no need for the middle part to be a circle, as it’s not a roundabout.

But looking closer at this, I’m wondering if we should the mini roundabouts as roundabouts. There is another Magic Roundabout in the UK (Way: ‪The Plough Roundabout‬ (‪664734455‬) | OpenStreetMap) and mini roundabouts are clearly signed there with “the blue circle sign”, but in Swindon one, I can’t see a single sign?

64

I just realised how strange and confusing it must be for British drivers to see a centre island of what is perceived as a roundabout, with bands of arrows pointing the wrong way! What the fork?

About the oval-abouts version: roundabouts are not necessarily exact circles, I have encountered half-abouts, dog-bone-abouts, icerink-abouts and freeform-abouts…
To map the access-abouts as OSM roundabouts, the approaches and exit should have separate junction nodes on the ‘circle’.

65

On 8 September 2023 23:38:45 CEST, Peter Elderson via OpenStreetMap Community Forum community@noreply.openstreetmap.org wrote:]

A dot in the middle won’t force the drivers to go around. They would simply see that as a nice divider, for safety.

You are totally missing the point, its about giving priority to traffic from the right (in the UK). Crossing a small painted circle is fine, in many places it would not be possible not to do so. At least not without slowing to a snails pace.

Larger mini roundabouts are often raised to discourage cars from driving over them, but allow large vehicles to cross them.

French mini-roundabouts do not have the blue sign https://wiki.openstreetmap.org/wiki/Road_signs_in_the_United_Kingdom#611.1 but do have normal give way signs. Drivers treat them the same as in the UK.

66

I have attempted to address these and uploaded a modified version.

67

I see the point, but I don’t see any need for a painted circle or dot when it’s only about priority and everyone will ignore the dot anyway. OTOH there are mini-roundabouts with separated approach/exit lanes and flares, where in principle you drive around the middle unless your vehicle simply can’t make the turn. Then I see value in the dot: it arranges priority and one-way drive-around regular traffic. Which is exactly what junction=roundabout implies.

68

Earlier in the thread there were other discussions about situations where mini-roundabout as a node causes confusing mapping and what tags to use on ones that might be better as ways. In the case of the Plough roundabout, the “main ring” is made of single carriageways so you don’t get the bowtie/sausage effect shape at the joins and is less confusing. Unfortunately the Swindon one is a ring of dual carriageway so it does have this issue (as I bemoaned in post #19 after I inadvertently derailed the conversation).

69

Still I think the Plough traffic circle would benefit from upgrading the roundabouts. It is really strange to see the approaches/exits join each other at single points on the large two-way ring. And I can see king size trucks going around the “mini”-roundabouts.

71

In the UK it’s illegal to drive over the white circle unless you can demonstrate your vehicle could not turn without doing so.

The white circle is there to make everyone go around it, unless a vehicle is large vehicles that can’t and then MUST go over the least amount possible.

Drivers can ignore the white circle, in the same way they can ignore a Red Light, or a Speed Limit. But if they do so they may be prosecuted. I have personally submitted video to police of a driver ignoring a white circle on a mini-roundabout that led to a the driver having to attend a training course.

In the UK mini-roundabouts also have different rules for signalling. Standard roundabouts have complex to describe signaling, (notable part is having to signal left when leaving the roundabout). But when approaching a mini-roundabout you simply signal as you would a standard junctions.

72

I’m sure this is true - in Nederland we would simply call that a roundabout. Unless it’s so small that, say, a funeral car can’t even make the required turn without touching the circle. If you can’t really circle around, we would not consider it a roundabout. Still, a raised centre circle helps as a traffic calming device.

I was told the signalling is not a legal thing? In Nederland we are advised to signal only when exiting the roundabout, not when entering, but many drivers signal at entry, and then to indicate where you want to go (right is next exit, left is to the -most often- third exit), not the actual movement which is alway a right turn for us. I think that matches “signaling as you would at a standard junction”.

This doesn’t even change at large multi-lane roundabouts: people will signal which lane they are going to take.

73

Once upon a time I was told that you indicate continuing on the roundabout when doing a 180-270 on a 4 way, but then that was abandoned, Till today I do that to let other drivers know what my intentions are, thusly if I drive on the inside, the one who’s planning a 90 can anticipate. As for indicating the exit, I do, others… OFL.

74

I’m sure this is true - in Nederland we would simply call that a roundabout. Unless it’s so small that, say, a funeral car can’t even make the required turn without touching the circle. If you can’t really circle around, we would not consider it a roundabout. Still, a raised centre circle helps as a traffic calming device.

Some are so small a normal car cannot turn right without without touching or crossing the circle.

They are often used at former cross roads or T junctions to equalise priority, where traffic flow on the priority route can effectively block traffic leaving side roads

The roundabout comes from the system of priority. Roundabout being named after the fairground ride, if roundabouts had originated in the US they would be called carrousels.

I was told the signalling is not a legal thing? In Nederland we are advised to signal only when exiting the roundabout, not when entering, but many drivers signal at entry, and then to indicate where you want to go (right is next exit, left is to the -most often- third exit), not the actual movement which is alway a right turn for us. I think that matches “signaling as you would at a standard junction”.
That is how most drivers in the UK do it, same in France although many french drivers take roundabouts much slower the British drivers do, but they aren’t a new idea for us.

Maybe travel and experience driving in different countries?

Usual approach in new countries is to be cautious and observe how the locals do it. The first one for a British driver in France is to take roundabouts slower.

75

I don’t think that geometry should be a deciding factor of chosing one tagging or another. You can always chose not to divide roads on island (and just map the island as traffic island). But honestly, I don’t think that separating roads looks that bad when the mini roundabouts are mapped as nodes.
What we should think is the function of those. Are mini roudabouts closer to normal junctions or to roundabouts? Should the driver get a command “Take 3rd exit” or “Turn left” when arriving to those?
Also, weirdly the topic was “taken over” by magic roundabouts. They are interesting and complicated, but there are not common. Like, how many magic roundabouts are there in the world? 10?

76

Well. if anything, this discussion shows that there are mini_roundabouts which are like disguised regular junctions, then there are mini_roundabouts which are actually two-lane roundabouts without the centerpiece.
So to the question “are they A or are they B” I can only answer: some are more like A and some are more like B. If you decide to map the B’s with a junction=roundabout ring and one way per separated carriageway, and the A’s with highway=junction nodes, you’re only concern is with the edge cases. My answer: let the mappers decide. Maybe by preference, maybe convention, maybe other considerations. Maybe the first mapper simply puts a node, the second just turns it into a ring, and the third has more time to spare and creates a roundabout with flares, turn restrictions and nice fluent bus relations.

My turning point would be when at least one of the roads physically splits into separated approach and exit lane. That would almost certainly mean that there is enough room for a true circular movement, which makes it a roundabout (provided the signs and markings are there).

Peter Elderson

1 Like
77

Picking one with islands which I am familiar with and remember when it was a cross roads.

https://mapillary.com/map/im/413175356874268

Whilst it is big enough for a car to avoid touching the paint. There is no way that the double deckers, which turn there can avoid it.

78

Danke @trigpoint und sorry, dass ich heute auf Deutsch antworte. Ich hoffe der translate-button macht einen guten Job.
Danke nochmals - das sind die mini-roundabouts über die wir hier diskutieren sollten. Nicht über magic-roundabouts, dass sind ganz besondere Spezialfälle. Dieser ovale mini-roundabout hat einen Außendurchmesser zwischen 20 und 25 Meter - das ist groß genug, dass man ihn als roundabout zeichnen könnte. Aber zu klein, dass ein großer LKW mit Anhänger den Kreis zu 3/4 durchfahren kann, ohne die Mittelinsel zu überfahren - deshalb ist die Mittelinsel baulich so gestaltet, dass sie im Ausnahmefall auch überfahren werden kann.

Dieser Kreisverkehr ist ein mini-roundabout, weil der Verkehr im Kreis Vorfahrt hat, die Mittelinsel überfahrbar ist und speziell in GB als mini-roundabout beschildert ist. Derzeit gibt es in OSM faktisch nur eine Möglichkeit, diese Kriterien abzubilden: als Punkt mit highway=mini_roundabout.
Wenn man diese Kreisverkehr detaillierter mappen möchte, insbesondere die Ein- und Ausfahrten der Dominion Road, bekommt man geometrisch seltsame Gebilde. Wenn man den mini-roundabout dagegen als Kreis (oder Oval) zeichnet und mit junction=roundabout taggt, kann man auch die Ein- und Ausfahrten exakt abbilden, verliert aber die Information, dass die Mittelinsel überfahrbar ist, denn dies kann durch einen kreisförmigen way nicht abgebildet werden.

Offensichtlich werden auch in GB, wo der mini_roundabout erfunden wurde, die mini_roundabouts immer größer (ich habe gelesen: bis zu einem Außendurchmesser von 28 m). Es besteht auch in GB zunehmend Bedarf, die größeren mini-roundabouts nicht mehr nur als Punkt, sondern als kreisförmigen way abzubilden - aber auch die Information darüber in der Datenbank zu haben, dass die Mittelinsel überfahrbar ist (und speziell in GB, dass der Kreisverkehr ein mini-roundabout ist, weil er so beschildert ist).

Wir haben daher im deutschen Forum nach der dritten oder vierten ewig langen Diskussion den key central_island:traversable entwickelt, um diese Problem zu lösen.

translated:
Thanks @trigpoint and sorry for replying in German today. I hope the translate-button does a good job.
Thanks again - these are the mini-roundabouts we should be discussing here. Not about magic-roundabouts, those are very special cases. This oval mini-roundabout has an outer diameter of between 20 and 25 metres - that’s big enough that you could draw it as a roundabout. But it is too small for a large lorry with a trailer to drive 3/4 of the way through the roundabout without driving over the central island - which is why the central island is structurally designed in such a way that it can also be driven over in exceptional cases.

This roundabout is a mini-roundabout because traffic has the right of way in the circle, the central island can be driven over and is specifically signposted in GB as a mini-roundabout. Currently, there is effectively only one way to map these criteria in OSM: as a point with highway=mini_roundabout.
If you want to map these roundabouts in more detail, especially the entrances and exits of Dominion Road, you get geometrically strange shapes. If, on the other hand, you draw the mini-roundabout as a circle (or oval) and tag it with junction=roundabout, you can also map the entrances and exits exactly, but you lose the information that the central island can be driven over, because this cannot be mapped by a circular way.

Obviously, also in GB, where the mini_roundabout was invented, the mini_roundabouts are getting bigger and bigger (I read: up to an outer diameter of 28 m).

There is also an increasing need in GB to map the larger mini-roundabouts not only as a point but as a circular way - but also to have the information in the database that the central island can be crossed (and especially in GB that the roundabout is a mini-roundabout because it is signposted that way).

We have therefore developed the key central_island:traversable in the German forum after the third or fourth eternally long discussion to solve this problem.

1 Like
79

That solves the issue for me. We would still need a “non-node” version of mini roundabout, and mappers would chose which version match in a specific case. We only need to make sure to clearly put in a description of the tag, that the difference is a FUNCTION not GEOMETRY.

2 Likes
80

Where are the other rules? In highway code rule 188 I only find half a sentence:

Remember, there is … less time to signal.

In my opinion, this is not a different rule, but only a reference to the fact that the left-hand signal is often not given and that you should therefore be careful.

Or in other words:

You will find that when driving around mini-roundabouts there is less room to manoeuvre and less time to signal, so take extra care.

81

@Peter_Elderson I was recently on holiday in the Netherlands for a week. I think your country is just great!
Of course I had to drive a lot to visit this and that. I saw many roundabouts in North Holland, bigger and smaller ones and lots of turbo roundabouts. But I didn’t see any mini-roundabouts! I don’t know if there are any mini-roundabouts in the Netherlands.

But I have often seen such circles, not coloured but paved differently, sometimes slightly elevated.
https://www.mapillary.com/app/?pKey=974340876710211
These are indeed not mini-roundabouts. They are, as you wrote, rather traffic calming measures or simply indications of junctions with the same priority (right-hand-priority) or simple decoration.