Each direction of travel on a road can have a speed set on it. Waze uses the speed limit to (optionally) warn the driver when they're exceeding the limit. Editors should map the speed limits on roads with the following considerations:
- Map the legal speed limit, not the opinion of the editor e.g. speed limits in car parks.
- Avoid mapping speed limits on roundabouts, as they have no use.
- Do not map advisory speeds, only speed limits.
- Where variable speed limits are in use (such as digital signs or alternate speed when raining), editors should always map at the higher speed limit.
The standard elevation for all roads not intersecting is 0 (Ground).
Otherwise, we apply The Seagull Rule:
- If a seagull can fly right under it, it’s a bridge (Level 1+).
- Seagulls don't fly underground, these are tunnels (Level -1 and lower)
- For every other case the road is ground level (Level 0), even if it’s artificially elevated or dug under street level.
- We mark bridges with level = +1.
- We only mark a road as level +2 if there’s another bridge (+1) running underneath it.
- Same logic applies for tunnels (in opposite direction), and further (+3,4 & -3,-4).