OpenStreetMap 開放街圖
Last month, we released the Missing Roads plugin and web tool. This quickly became a popular pastime for quite a few mappers - one month later, more than 20% of all the Missing Road tiles have already been resolved :)
For the darker and colder November days – well, if you are on the Northern hemisphere at least – we thought we would cook up something new to keep us all busy. We ran another analysis on our GPS data to uncover ways that probably do not have the right directionality. Either they should be oneway=yes and they are not, or they are oneway=yes but in the wrong direction.
Here is an example from Karlsruhe, Germany:
The orange arrow points in the direction we think traffic on that street flows based on what we know from our Scout GPS data.
The way we do this is by looking at the directionality of the GPS tracks. If more than, say, 90% of all tracks matched to an OSM way go in a single direction, it is pretty safe to assume that it is a one-way street. We then compare that to how the way is mapped in OSM. If there is no correct oneway tag on the way, you will see the way in this tool.
Let’s open the earlier example up in JOSM:
This looks a bit cluttered because there is so much OSM data, but if we zoom in a bit and make the OSM data layer invisible for a moment, we can see from the direction the cars are parked and the arrows on the road that this is indeed a one-way street:
Aerial imagery in JOSM from Bing
We found more than 140.000 (!) of these cases all over the world waiting for us to fix them. This works almost exactly the same as in our Missing Roads plugin and web tool we released last month. You can look at the Missing Roads manual. (I will write a proper manual for the One-way plugin and tool soon.)
Here is the address for the web tool: http://improve-osm.org/trafficFlowDirection. You can find the JOSM plugin in the JOSM plugin preferences. The source code for the plugin is on Github as always. We started a wiki page for the plugin as well.
Happy mapping and please, as always, let me know what you think :)
討論
由 Sanderd17 於 2015年10月30日 16時22分 發表的評論
Nice tool, though I’m seeing certain issues.
First of all, in my area, most of the issues found seem to be very short road pieces, only a few meters long, part of a big road. They’re split up because of route relations, or changes to tags like speed limits. Is there something that makes detecting these small segments easier? See most issues in this area: http://improve-osm.org/trafficFlowDirection/#11/51.0008/3.0933
Secondly, do you take dates into account? Traffic layouts change often, and streets might change their oneway direction. Perhaps it can be detected by seeing that from a certain date on, 90% of traffic rides in one direction (if the sample is big enough).
由 naoliv 於 2015年10月30日 17時14分 發表的評論
Suggestion: make it possible to mark invalid/false positives using the web interface. Idea: also use OSM’s GPX tracks, if possible (in another layer, like suggest for the Missing Roads)
由 flohoff 於 2015年10月30日 17時27分 發表的評論
Very cool - I am talking about something like this for years. Critics always said that the 100% accuracy would not be possible and it would be to complicated to maintain the data. I was always advocating that one day we’ll have millions of users giving feedback about correctness and completeness of map data.
There we are …
Thanks a lot for proving this valuable feedback from your telemetry data.
由 StephaneP 於 2015年10月31日 09時42分 發表的評論
Nice tool ! But in my area, about 90% of the detected oneway, are invalid.
About the Josm plugin : I’m note sure if different button are useful. Perhaps only one with a checkbox solved/invalid. And I don’t understand why I must write a comment when I close a segment. If it’s invalid, there is nothing to explain, it’s …invalid.
由 k1wi 於 2015年10月31日 09時50分 發表的評論
I am seeing a lot of false positives. It seems that you are not considering that
junction=roundabouts are always oneway, they don’t need aoneway=yestag. Example: http://improve-osm.org/trafficFlowDirection/#16/42.8088/-1.6344由 bielebog 於 2015年10月31日 10時00分 發表的評論
That’s a neat tool. It’s good to see collected GPS data flow back into OSM improvements. It seems that one intrinsic flaw is that traffic that flows into underground parking lots gets properly tracked, but traffic flowing out might not due to GPS receivers getting a proper fix just later on the road. So flow of traffic might indicate a oneway flowing in where in reality traffic flows in both directions. Detecting underground parking entrances in the vicinity of end nodes of marked ways might be a plausibility indicator here.
由 _sev 於 2015年10月31日 11時19分 發表的評論
Also, it would be cool to take into account oneway=reversible tag:
http://improve-osm.org/trafficFlowDirection/#16/52.3294/5.0422
由 sabas88 於 2015年10月31日 21時40分 發表的評論
Nice, I fixed some streets already!
由 Hjart 於 2015年10月31日 22時01分 發表的評論
Very nice tool. Found a few gems already. The vast majority of what I’ve seen so far has been false positives though (long stretches of primarily secondary and primary roads, which actually are bidirectional, but not dual carriageway)
由 mvexel 於 2015年11月 1日 23時08分 發表的評論
Hi everyone - thanks a lot for trying out the tool and sharing your experiences. We will be working on improvements to reduce the false positive cases and your responses will be very helpful in doing that. Here’s what I see so far:
Very short segments
There seem to be more false positives among these. We will look into filtering these out or otherwise dealing with them.
Using OSM GPS tracks
We will be looking into that. I will check in with Grant to see if we can get a fresh dump of GPS traces. (The most recent one is from 2013.)
Changes over time
Local traffic rules / patterns may change over time, we can see if we can detect changes in traffic flow. We currently do not do that yet.
Roundabout and other less common
onewaytaggingRoundabouts are implicitly oneway, we will look into filtering these. Also look at
oneway=reversible.Other improvements
Please try and send a location with any problem you find, so we can reproduce it. That makes it much easier to act on any reported issue. Thanks!
由 literan 於 2015年11月 2日 09時20分 發表的評論
Please do not touch Moscow (Russia) with this instrument. Many streets here have got one-directional this summer and autumn, so there may be two-directional gps-tracks there.
由 mvexel 於 2015年11月 2日 15時04分 發表的評論
literan – I only found one case in Moscow: http://improve-osm.org/trafficFlowDirection/#17/55.76057/37.62802 - should this be marked as an invalid case?
由 RobJN 於 2015年11月 2日 23時59分 發表的評論
How frequently do you update the heat map on the website? I’ll recheck my area when it’s next updated.
由 Glassman 於 2015年11月 3日 00時42分 發表的評論
Nice fixes. I really like the statistics for the way. Still false positives, but not sure software could be improved anymore. I’m finding two types of false positives, ferry terminals and apartment service roads. At the Clinton Ferry in WA State, people don’t drive in the correct lane as they drive onto the ferry. If they did you’d see two way traffic. The apartment service roads just have small amount of traffic. Might be just one person going out/in the same way each time.
One suggestions - please have the orange circle updated as well when the way is either marked as fixed or invalid, similar to Missing Roads.
由 matrioszka 於 2015年11月 3日 11時34分 發表的評論
thanks for this info :) its very helpful and useful for me
由 andrewpmk 於 2015年11月 8日 03時30分 發表的評論
There are a lot of false positives caused by highway offramps leading to and from a two way road (most often, a service road parallel to the highway). Most of the traffic is going one way, but it is possible to go the other way.
由 mvexel 於 2015年11月 8日 04時56分 發表的評論
andrewpmk – acknowledged. those are hard to filter out purely based on trips, because like you said, the majority of folks will be driving in one direction. Is there distinctive tagging that we could use to give those cases lower importance?