Welcome to my Waze wiki page
The Road Elevation should be changed where one road passes over another. By default, the Elevation of a segment is Ground (zero). When two segments overlap but do not actually connect in the real world, the value of Elevation for each segment must be different. This ensures that the Waze problem detection system doesn't flag the spot where two segments overlap as a location where a junction might be needed.
The visual representation of the relative Road Elevation is different when viewed in the Waze Map Editor (WME) and the Client application.
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 currently 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. Please refer to your local (State/Country/Provence/Regional/etc.) Wiki page for local guidance since there are some occasional variations. The main guidance is: Lowest Road that sees the sky is "ground" and then raise the elevation for the subsequent road segments up as required. Roads that go under buildings or a body of water would be tunnels and have negative elevation (and marked as tunnel appropriately). This is sometimes called the seagull approach.
4. Bridges - Mark a bridge at the start and the end as tight as possible on the actual start and stop of the bridge. Don't worry about excessive nodes to mark a bridge. If there are two (or more bridges) then mark the start and stop of each one. The road segment(s) in the middle should be one elevation less than the bridge.
5. Tunnels - Mark a tunnel tight but not as tight as a bridge. Leave at least 15 m (49.21 ft) BEFORE and AFTER the tunnel and don't forget to tick the Tunnel checkbox for the segment going through the tunnel. The reason for the 15 m (49.21 ft) is to allow that each tunnel segment has GPS lock before and after the tunnel.
6. Non-drivable roads - Please follow the road segment elevation guidance for non-driveable roads. Previous guidance called for elevations of -5 or +9 on non-drivable roads. This is no longer required. As of the end of 2015 guidance changed to treat elevations on non-drivable segments the same as elevations on any other segment.