Fast Traffic Sign Mapping with OpenStreetMap and Mapillary
This post was originally published on the Mapbox blog.
Mapping traffic signs on OpenStreetMap just got a lot faster. The latest version of OpenStreetMap’s iD map editor highlights features detected in Mapillary imagery directly in the map view, vastly speeding up the mapping process. This work is courtesy of my colleague Kushan Joshi and leverages Mapillary’s machine learning based sign detection.
This new functionality particularly aids mapping traffic signs like stop signs, turn restrictions, exit numbers, and destination signs—all data that means more accurate ETAs, better instructions, and ultimately less time waiting in traffic.
To get started, open the Map Data panel and click the checkboxes to show the
Photo Overlay and
Traffic Sign layers in iD.
To add a stop sign, place a point along the road at the stop position, then choose the
Stop Sign feature type. You should also check the direction of the road, as indicated by the small triangles that are drawn along the road. Fill in the
Forward if the sign is for traffic driving in the same direction that the road is drawn, or
Backward if the sign is for traffic driving in the opposite direction.
To map a turn restriction, click on the junction point between the two roads. A turn restriction editor will appear in the sidebar. Select the road entering the intersection and then choose which turns are allowed or restricted.
To map a highway exit, select the junction node where the “link road” splits off from the main highway. Make sure the node is tagged as a
Motorway Junction / Exit and add the exit number to the
Junction Number field.
To map highway destinations, select the “link road” that splits off from the main highway. You will need to open the
All Tags section in the sidebar and add the tags that describe the destinations that this link road leads to. When multiple destinations appear on a sign, you can separate them with a semicolon.
In the example below:
destination=Morristown;Somerville—destinations as they appear on the highway sign.
destination:ref=I 287—route numbers or shields that appear on the highway sign.
destination:ref:to=US 202;US 206—use the
:to suffix for routes where the sign says “To”. These routes are secondary destinations for the highway exit.
Check out the Mapbox mapping guide to learn more about the tags used in highway exit and destination mapping.
Try editing OpenStreetMap in your town and see how many traffic signs you can find. Follow me on Twitter for more tips on using street-level imagery to improve OpenStreetMap.