From Wazeopedia
Road elevation

Road Elevation is used to indicate the relative height of roads to one another, not the absolute height. The default is ground, but it can be set lower (negative number) or higher. It is usually only needs to be set where one road passes over another, though Waze may support different visuals in the future for various elevations.

When two segments overlap but do not actually connect in the real world, they must have different Elevation values. Otherwise, Waze may generate a Map Problem report. If two roads cross at grade but traffic does not pass from one to the other, set a junction anyway, with all turns disallowed. See the similar discussion on Railroads at the end of this section.

The visual representation of the relative Road Elevation is different when viewed in the Waze Map Editor (WME) and the Client application. Details of the visual representation can be found at the end of this section.

Consistency Issue: There is a known problem with the editor, where the Elevation value may display incorrectly. If you see blank elevations, or the elevation value is inconsistent with what you have set or seen before for a segment, then you must refresh the page. The multiple Waze servers storing road data sometimes are sometimes briefly out of sync for Elevation values.

Crossed segment display and elevation in the App, Livemap, and the editor (WME):

1. The Client App displays segment elevation based on the road type only, meaning Freeways are always on top, Major Highways are next, followed by Minor Highways, Ramps next, Primary Streets below all those, and finally Streets are at the bottom. This is the same order seen when setting the road type in the editor.

2. The WME uses the Road Elevation setting to display the relative elevation of the road. It displays the road with the highest "elevation" number at the top of the visual stack and works its way down as would be expected.

Although the client application does not benefit from the Road Elevation setting, it is recommended to set the Road Elevation relative to the physical mapping in the real world to enable possible future Client application updates to show the same visual representation as the WME.

3. Special handling for non-drivable roads: Elevation -5 (negative 5, the lowest possible elevation value) is used for some non-drivable roads, such as walking trails and boardwalks. This prevents Waze from falsely noting that the roads should be connected. Otherwise, Waze may report "missing junction" errors, and may also incorrectly route drivers onto the non-roads. This is no longer true for railroads. At-grade railroad beds should now be set to Elevation=Ground, and a no-turns junction made at railroad crossings. If you come across railroads using the old -5 setting, you may set them to the correct value, but there is no need to do this en masse.

See Bridges for more information on elevation.

See Locked Segments for information on road ranks.