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I have a lot of trouble distinguishing the direction of a oneway highway in JOSM. Usually, I select the segment and note the direction in which the big arrowhead is pointing. When the segment is not selected there are small arrows inside the rendered way that do not necessarily point in that same direction. The rendering for tertiary highways is worse than that for primaries or trunks-- deciphering the direction those tiny "arrowheads" are pointing (if indeed they are pointing) is practically impossible. Very confusing.

Adding to that confusion is the fact that I'm mapping in a country where you drive on the opposite side from the U.S. and the situation can be very error prone.

Help me understand the best way to visualize the direction of a oneway segment.

asked 24 Dec '13, 05:52

AlaskaDave's gravatar image

accept rate: 16%


Can you please post a screenshot? Maybe this problem is caused by your resolution etc. as personally I don't have problems to identify oneway roads in the default style :(

(24 Dec '13, 07:35) iii

In addition to Hendrikklaas's answer, some settings you can play with in edit -> preferences -> display (first icon) -> OSM data :

  • Draw direction arrows (of the osm way itself, regardless of oneway setting)
  • Only at the head of a way (I find this clearer)
  • Draw oneway arrows (you definitely want this one)
  • Smooth map graphics (try both; turn it off if you load a lot of data and/or have a slow computer)

If those easy changes aren't enough, you might be able to tweak the oneway arrow style explicitly :

  • Create a mystle.mapcss file somewhere
  • Put :way[oneway=yes]::arrows { z-index: 15; color: #555555; width: 4; dashes: 10,50; }
  • Play with the values to get something you like (I haven't managed to change the arrow itself, it is probably hardcoded)
  • Go to preferences -> map setting -> map paint styles, and add your own style file (by clicking the "+" on the right).
  • Close the preferences and activate the style in the map paint styles dialog (alt+shift+m).
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answered 24 Dec '13, 10:46

Vincent%20de%20Phily's gravatar image

Vincent de P... ♦
accept rate: 19%


That is exactly what I was looking for. Adding the arrow at the head of the way works wonderfully.

I'll try the paint style too, but right now I have some multi-lane intersections to check for correctness.


(24 Dec '13, 16:30) AlaskaDave

@Vincent - I've been playing around with the mapcss file and would like to understand the various parameters. Can you point me to a tutorial or language reference? My Google searches haven't found anything worthwhile ....

(25 Dec '13, 03:53) AlaskaDave

@AlaskaDave See the reference page or this tutorial or just the styles page which links to them. The documentation isn'guaranteed to match the latest implementation.

(27 Dec '13, 00:07) Vincent de P... ♦

Thanks Vincent - I've tried many things but none seem to work exactly as advertised. Plus, the custom styles that do work "get remembered" after I update the mapcss file.

I tried to come up with a style that would better illustrate the oneway direction but have given that up and settled for merely displaying the direction arrow at the head of the ways, as you suggested in bullet 2 above.

(27 Dec '13, 02:16) AlaskaDave

Alaskadave, visualizing a way is part of the rendering, you won’t be able to change that. The direction of a way is managed with the tags in the advanced menus. Look here,

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answered 24 Dec '13, 09:13

Hendrikklaas's gravatar image

accept rate: 5%


"you won’t be able to change that" <- yes you will, you can create your own MapCSS style (as Vincent has correctly explained)

(24 Dec '13, 11:10) Richard ♦

Off course a local map, dont tag for the renderer isnt a frase, is it ?

(24 Dec '13, 12:25) Hendrikklaas

The question is about an editor and likewise Richard/Vincent meant changing the editor's stylesheet.

(24 Dec '13, 12:48) scai ♦

An oldy while I was looking for a render problem solution in Rapino, Via Fiume

Followed all of the above while using JOSM 18583, always latest stable. Changed a oneway direction using the R key. The red arrow while selected changed direction, the pop-up window proposed to change direction value to oneway=-1 value (yes). Before the change and the way not selected, the way shows grey with little black triangles pointing east. After the change the little black triangles still point east, when the oneway that is on the other side of the block points west with oneway=yes, correctly.

Then, I got a QA alert next day to say the -1 value is deprecated and should use the reverse function to set the direction. Checking in ID Editor indeed the -1 value is on the oneway and then using the reverse in ID twice, the value changed is back to yes, it is in fact in ID always yes. The arrows on the way in ID properly change direction with each reverse operation.

So, does JOSM have 1) a render problem for the little black triangles. 2) an issue with using deprecated value for oneway, either yes or -1

(01 Dec '22, 08:28) SekeRob

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question asked: 24 Dec '13, 05:52

question was seen: 6,027 times

last updated: 01 Dec '22, 08:28

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