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I've run into this tag combo on traffic signals on 4th Avenue in Brooklyn, NY:

I only see two other cities where this combo shows up in decent numbers -- Oklahoma City and Rosario, Argentina. Then there are a few pockets in India and scattered around Europe.

Does side=right actually mean anything useful? I can't find any trace of it in the wiki.

Looking at the 4th Avenue example, it seems to be related to the fact that this road is divided and mapped as two parallel ways, each with oneway=yes, but there are plenty of other roads mapped like that (opposite directions mapped as separate ways) that don't have a side tag on their signals.

(side=left is also present in very small numbers around the globe.)

asked 11 Jun '18, 21:47

jmapb's gravatar image

accept rate: 22%


You can always try to contact one of the contributors that added this tag to find out what it means

(12 Jun '18, 04:07) escada

Thanks, yes, I've done that.

(13 Jun '18, 16:11) jmapb

Could it be that the signal is mounted on a pole that's on one side of the road? Of course, if nobody has documented the tag in the wiki, then all we can do is guess what its intended meaning is.

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answered 11 Jun '18, 21:58

alester's gravatar image

accept rate: 28%

Based on the very few occurrences of highway=traffic_signals+side=left that I've been able to investigate, I believe that this is correct: mappers have used this tag to indicate that a traffic light is mounted on a pole on the left side of the intersection. Of course right is much more common than left, at least in drive-on-the-right-side countries.

I'm not sure what the utility of this information is, but who am I to judge? It's also quite possible for the signal to be on the left for some traffic and on the right for traffic in a different direction, not sure how you'd tag that.

According to the mapper, the signals along 4th Ave in Brooklyn were tagged side=right at the suggestion of a JOSM plugin tool, which seemed appropriate because it was being mapped as two opposite-direction ways ("dual carriageway"). Still haven't found any actual documentation on the tag itself, but I'm calling the mystery solved for now. Thanks, J

(13 Jun '18, 17:27) jmapb

Finally found the side tag documented. The JOSM tool in question is "Traffic_signs_US" which can enabled under Map Settings->Tagging Presets. The tags used, including side, are discussed on the wiki at

In this proposal, the side tag will indicate which side of the way signs and signals are on.

(I've added some "related terms" to that page so hopefully it'll be easier to find in the future.)

(19 Jun '18, 15:38) jmapb

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question asked: 11 Jun '18, 21:47

question was seen: 1,598 times

last updated: 19 Jun '18, 15:38

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum