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= Left- and right-hand traffic =
JOSM has an internal database of areas with left-hand traffic since version r7193.

The database is used e.g. in the following places:
* The default internal mappaint style (for cycleway lanes and tracks on highways and roundabout icons)
* [wiki:Styles/Lane_and_Road_Attributes Lane and Road Attributes] style
* [wiki:Styles/Maxspeed Maxspeed] style (for maxspeed:forward and maxspeed:backward)
* For the create circle action, to use the correct way direction, if you create a roundabout (since r8303).

You can download the data [http://josm.openstreetmap.de/browser/josm/trunk/data/left-right-hand-traffic.osm here] (click on ''Original format'' on the bottom of the page) and load the file in JOSM to investigate the borders. The areas in the file describe the areas with left-hand traffic. All other areas use right-hand traffic.

You can use the pseudo classes `:righthandtraffic` for right-hand traffic and `!:righthandtraffic` for left-hand traffic or the eval expression `is_right_hand_traffic()` in your [[Styles/|mapcss mappaint style]]. See [[Help/Styles/MapCSSImplementation]] for more information. Note that you maybe get wrong results near to borders of countries with different driving directions since the area borders of left-hand traffic are simplified in JOSM. These simplifications are necessary to reduce the size of the database, but it can be refined on request.

If you notice an error in the database you can create a new ticket by clicking in JOSM menu Help → [[Image(source:trunk/images/bug.png,20px,middle)]] [wiki:Help/Action/ReportBug Report bug].

Screenshot of the areas with left-hand traffic:

[[Image(leftrighthandtraffic.png)]]

^(data used for image [osmwww:copyright ©OpenStreetMap contributors] ODbL, tiles: Mapnik CC BY-SA) ^