Waze map editors use the term basemap to refer to roads imported from external sources that have never been edited and for areas that contain them.
Background
A basemap (or base map) is a collection of reference data intended to provide visual orientation to users of a map, so that further details can be added and displayed on it in a meaningful way. It may include data on imagery, topography, roads, political boundaries or other things, depending on the purpose of the map. In many countries, Waze has licensed and imported data on roads and other features from various sources to serve as its basemap, and this is the foundation upon which users and map editors build to create a usable navigation system.
Depending on the data source used to import roads for each particular country, basemap roads require various updates from map editors in order to provide efficient navigation and useful display. This can involve confirming directions, turns, and names, adjusting geometry and connectivity, removing extraneous nodes and segments and setting road types, locks, elevations and other road attributes. Because they require specifial cleanup from editors, and because they contain unique features relative to roads created and edited by users, map editors often refer to these unedited roads and areas that contain them simply as basemap.
Basemap roads in the United States
Waze imported TIGER data from the US Census Bureau to serve as its basemap in January, 2009. TIGER data provided somewhat accurate names, locations and cities/states for roads, but it did not include road directions, allowed turns, distinctions between road types beyond Street , Private Road or Unpaved , or any navigation history. Because this data was designed for location of people and places and not for navigation, it contained many odd angles and extraneous geometry and junction nodes when added to the Waze map.
Basemap roads in the USA have unknown direction and soft restricted turns by default, but Waze is designed so that users add data to roads as they drive over them. When enough users drive over a road of unknown direction from node A to node B onto another segment, Waze will automatically set the direction to one way (A→B) and will set the turn from node B onto the other segment to soft enabled. If enough users drive from B to A on this same segment, Waze will then set the road to two way, but the turns will still be unconfirmed. These directions and turns remain guesses and are affected by various routing penalties until set by an editor. Once a segment is edited and its turns are confirmed, penalties no longer apply to enabled turns, and any restricted turns and forbidden directions become absolute and will not be routed.
Identifying unedited basemap roads
Basemap areas are usually found where there are few GPS tracks. A lack of GPS tracks over roads could mean that there are not many Wazers driving there, that cellular data coverage is weak or even that the roads on the map are not drivable or do not exist. Whatever the reason, lack of GPS tracks is a good clue that unedited basemap roads are nearby, waiting to be edited.
It's easy to tell when the basemap roads were imported into an area, because most road segments will have the same creation date. If a road segment has that created date but does not have an updated date listed in its information, it is an unedited basemap road that needs to be updated. Additionally, features like unknown direction, unconfirmed turns, odd angles, excess nodes and segments that don't match imagery are clues that a road has not been edited much from its basemap state, even if it has been updated by someone.
Editing basemap roads
The general information on Creating and editing road segments applies to editing basemap roads, but basemap roads have some unique features to look out for. Editors should watch for and fix the following things when editing basemap roads:
- Delete unnecessary road segments. Some basemap roads represent driveways, walking trails, fences, waterways or nothing discernible at all. With few exceptions these should be removed from the map. Deleting these provides a more accurate map, better navigation and less work for editors.
- Adjust the connectivity. Oftentimes basemap roads will not connect where satellite imagery shows they should. They should be connected to provide proper routing. Any one-segment or two-segment loops should be fixed.
- Delete unnecessary junction nodes. This allows Waze to use less resources when calculating routes and to give more accurate arrival times.
- Set the direction. If the direction of a road is unknown or one way, determine what direction the road should be and set it. Remember that once you edit a one-way segment, even if you don't change the direction, Waze will consider its direction confirmed and will not route traffic in the opposite direction.
- Set the turns. Hidden turns are revealed after the direction has been set. Confirm the turns; keyboard shortcuts such as Shift+Z to reveal restricted turns and Q+W on a node to allow all turns can help with this.
- Confirm the name and city. The road names page and approved sources can help determine names.
- Adjust the geometry. Most basemap roads will have excess geometry nodes that should be removed to use less resources during navigation and to make the map easier to maintain. Most basemap roads will also not be aligned very well with satellite imagery. Where the imagery is accurate, they should be adjusted to match it. Geonodes should also be adjusted around intersections to provide proper turn instructions.
- Set the road type. Satellite imagery can often determine whether a road is paved or not; see road types for more information.
- Set the elevation. Usually this is ground, but some basemap imports have unrealistic elevations that should be corrected.
- Set other road attributes. If a road has not been edited by anyone in Waze, it is unlikely that Google has street view to show speed limit signs, but it's good to check. Sometimes default speed limits can be added based on applicable laws. Depending on road type, a lock may also be warranted.