I think in this case the “overtaking lane” can be determined by the forward lane count, if it’s >1 then you can overtake (without crossing into incoming traffic).
I’m not aware of any way to mark these as designated overtaking places beyond that, and I didn’t have the sign included in Australian Tagging Guidelines/Road Signage - OpenStreetMap Wiki but checking Traffic Signs | Transport for NSW there are a few standard sign there, so you could use traffic_sign tagging to map the signage, which can be linked to locations the sign appears along the road.
The overtaking key is about overtaking by crossing into incoming traffic, a bit different that your scenario.
It is correctly mapped for that section as 2 lanes forward, 1 back. I certainly would have added divider=double_solid_line which over here indicates no crossing i.e. no overtaking on the 1 lane directions. Maybe overtaking:backward=no. which has 2423 uses per tag info but I know zip about Australian traffic rules and signage.
In general (Continental 2+1 lanes road, UK WS2+1 wide single carriageway with alternating overtaking sections), you could infer this by having turn:lanes:forward=none|merge_to_left at the end of the overtaking section, in the absence of intersections and turn:lanes:forward=through|right (thus not a right-turn lane)
However, the example is a less desirable conforming layout by newer standards worldwide. The original main lane on the left merges after “gaining” an “auxilitary” overtaking lane, for the convenience of land uptake and roadway layout. Therefore, you can only use the lack of intersections as the criteria, as otherwise you can’t guess whether there’s a parallel merging lane for the minor road left turn into the major road, without the rare type=connectivity relating them.
There are climbing-overtaking lanes (to be contrasted from crawler lanes) for cars to overtake trucks uphill. They aren’t explicitly indicated either.
Often those are accompanied by the sign forbidding overtaking by trucks… else on these long uphills you sit behind the 2km faster overtaking hgv for the stretch of the uphill, negating the value of such an extra lane.
This is a really interesting question. I wonder if the tagging scheme is solid enough for a navigation app to announce the distance to the next passing/overtaking zone or lane? Or highlight passing allowed zones for the current travel direction as well as overtaking/passing lanes…
You’re thinkin about this from the same angle I am.
If I was to calc a route (with say Graph Hopper) it would be incredibly difficult to work out where the overtaking lanes are along that route. Yes, in theory I could detect where it is likely to be an overtaking lane, but (I believe) approprate tagging is the only way to achiveve certainty.
Having said that, I see no such tagging convention.
I’m trying to see why checking for lanes:forward > 1 would not work? When you change from lanes:forward = 1 to lanes:forward > 1 then an overtaking lane has opened up, when you change from lanes:forward > 1 to lanes:forward = 1 then an overtaking lane has closed.
Perhaps with an additional check that the section where the lane count is > 2 is long enough to be used to overtake.
This won’t tell you if it’s a “designated” overtaking lane, but if you’re just looking to overtake does that matter?
If we want to mark the road section itself as being a designated overtaking section, where there is signage labelling the additional lane(s) as overtaking, perhaps something like overtaking_lanes=designated / overtaking_lanes:forward=designated` could be used.
I would avoid using the overtaking=* key directly since that’s about crossing into incoming traffic.
I think it would be difficult to accurately detemine that it is a dedeicated lane because you would have to be aware that you have not made a “manouvre” from one “road to another etc”
It would also be problematic with these little dual lane sections…
Those, are not dedicated overtaking lanes. I’m not sure of the formal defination, but they are at intersections to give extra “room” for passing when one vehicle is turning and another is going straight on. Thus, not really for the purpose of overtaking.
Yeah, that scenario is what I had in mind when I mentioned
Perhaps with an additional check that the section where the lane count is > 2 is long enough to be used to overtake.
So then overtaking_lanes=designated tag would be the only way to know they are designated/signposted overtaking lanes, and would be the best tag to rely on for navigation guidance.
I saw a scenario where there is an “Overtaking lane in X meters” sign, then a “Keep left unless overtaking” sign, but no end signs and the lanes don’t merge again - https://www.mapillary.com/app/?pKey=1128623290984135&focus=photo. In this case I just did it for the section until the intersection. So I have overtaking=no (can’t cross the double line to into opposing traffic) + overtaking_lanes=designated (it’s signposted as having an overtaking lane available, so you can overtake vehicles without crossing into opposing traffic).
If we can map a bunch of these this way, to get the usage numbers up, and to battle test the tagging in real world tagging, then if we find it works well we can document it on the wiki as in use.
In Tassie we also have these “Slow vehicle turnouts’ where slow cars are meant to move left for others to overtake. Not sure if they would also be considered overtaking lanes and how they should be tagged.
Yeah, there are a few related concepts here. Many jurisdictions have a rule that slower traffic keeps right (or keeps left down under). Some jurisdictions (such as several U.S. states) have a stronger rule reserving the left lane for passing only. This passing-only lane could be hundreds of miles long. Either way, because it’s a uniform rule within the jurisdiction, it could be inferred from the lane count if necessary.
On the other hand, sometimes there’s a lane clearly designed for going to the side and letting faster traffic pass. It’s essentially what highway=passing_place is for, but in the form of a lane lengthwise. I don’t think we have a tag for these yet, and the example from Tasmania shows we could benefit from one, at least because of the signs.
Some steep inclines and declines come with an exceptional lane for slow traffic. In the U.S., this is most commonly signposted as a truck lane restriction, which we can tag as hgv:lanes=*. It also subtly implies that other slow vehicles should use the same lanes as the trucks, but this implication isn’t as clear as for trucks.
Australia seems to have at least some of these concepts. If you can align on a consistent tagging approach with similar situations in other countries, data consumers will be more likely to do something with the data.
Another sign in circulation which oddly gets placed on the central double sides guardrail of a motorway. (You have to know your rules as a wiseguy will make the argument that his truck can’t overtake cars, but can overtake trucks.) Placement is also prior entering the many tunnels in the motorway.
Yes we have that, there are rules about when it applies (something like roads 80km/h or more where there is more than one lane) so in those cases we don’t tag it since it’s based on the legislation.
The “overtaking lane” concept from Andrew (OP) applies where you have high speed and lengthy roads with only one lane in each direction, every so often the road will open up a second lane for a short section, to give drivers a chance to overtake. These a signposted and announced as such.
The approach you’ve laid out seems consistent with how we handle these situations in the U.S. At the federal level, passing lanes, truck lanes, and turnouts are indicated by advance guide signs. Then, at the point of a turnout, there can be a regulatory sign requiring slow vehicles to use it depending on current traffic:
But if there’s a full passing lane, then at most there would be the truck lane restriction, or more commonly no signposted restriction at all. So it goes back to the idea that we’d just tag the lane count and traffic signs. We’re currently recommending destination:lanes=* tagging on the traffic sign nodes, because these aren’t quite destinations at the same level of prominence as at junctions.
Seems confusing against overtaking:lanes= , and singular overtaking_lane= doesn’t look much better either. There are likely still two-way shared suicide lanes around the world.
It could be eg overtaking:same=designated / overtaking:same:forward=designated / overtaking:same:lanes:forward=*|designated (by imagining overtaking= as overtaking:opposite= side/direction )
On the other hand, using the physical aspect might be better in some sense. Eg =dedicated instead of =designated ; and =alternating , when a user don’t or can’t split it per section yet. Having this difference from overtaking= for the legality would favor overtaking_lane= more, however it’s still on its own. Eg lane_use:overtaking= can allow lane_use:crawler= , and other lane_use:*= if any.
Next question is whether the low (original lane merge into new lane) vs high (new lane merges back into original) standard design needs to be explicit. Inferring from turn:lanes:forward==merge_to_right|none vs =none|merge_to_left seems more complicated, and there could be auxiliary turning lanes messing up this detection. Can’t think of a good naming yet.
But worse, there’s the more complicated aspect of overtaking between different vehicles to consider. Although, the physical method does avoid this debate. Overtaking:be_overtaken:*=yes/no
That being said for all above, can motor_vehicle:lanes:forward:conditional=yes|designated @ (overtaking) be used first, before or instead of either new method? That would fit along eg hgv:lanes:forward= uphill nicely.
I think that works too, meaning this section of the road is designated for overtaking in the same direction by the “overtaking lane ahead” sign. This is for signposted overtaking sections, commonly where the road was built as a one lane (in your direction) road but opens up to 2 lanes (in your direction) occasionally to give a chance to overtake.
These overtaking sections may be a “keep left/right unless overtaking” but not necessary.
placement also provides some hints because it aligns the lanes.
This would work for “keep left/right unless overtaking”, (but that’s not necessarily the same as the “overtaking lane” concept) although I would reserve it explicitly signposted sections, anything that can be derived from legistration eg. (lanes>1 && maxspeed >= 80) could just be derived by the local driving rules rather than tagging this on every road that it applies?
For “keep left unless overtaking” it would just be access:lanes:forward:conditional=yes|designated @ (overtaking) because there’s no limits to the vehicle type that can use that lane for overtaking.
but I’m not sure if it’s always present.
