Routing penalties

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The Waze routing servers use a system that associates restricted turns and directions as a penalty amount. When it then compares the different routes, it looks at the cumulative penalty points and the lowest amount of penalty points is the better route.

Background

Waze routing is intended to work in two very different environments at the same time. One uses map information that has been carefully corrected by a group of dedicated editors. The other uses map information that was imported from an external database with no editor corrections. To support both systems the Waze development team decided to use a penalty-based routing system. That means the various segment and junction node properties that restrict certain directions between segments are applied as a routing penalty. For example, a turn restriction indicated by the red turn restriction arrow does not prohibit the turn, rather the turn restriction applies a high penalty to any route through the turn. This penalty-based routing system permits routing to a point on street where all turns onto the street are incorrectly set as restricted. This provides for some routing in areas that have not been edited carefully or correctly.

Segment properties

The following segment properties cause routing penalties:

• Turn restrictions and scheduled turn restrictions during the designated time for the designated vehicle type.
• One-way roads against the designated direction of travel and scheduled segment restrictions for the designated time for the designated vehicle type.
• Non-drivable road types including Walking Trail, Pedestrian Boardwalk, Stairway, Railroad and Runway/Taxiway.
• Toll roads for clients with avoid toll roads selected in the app.
• Dirt road/4x4 Trail for clients with avoid dirt roads selected in the app.
• Parking lot roads and private roads when transitioning to another road type

Road configurations

Other routing penalties are based on road configurations.

• 

  Segment too short to allow two left turns

  Waze will penalize a route with two left turns in less than 52.49 ft (16 m) in right-hand traffic jurisdictions or with two right turns in less than 52.49 ft (16 m) in left-hand traffic jurisdictions.

• 

  Ramps should prevent detour

  Waze penalizes some routes that leave a highway or freeway only to immediately return to the same freeway or highway. This is covered in more detail in Detour Prevention Mechanisms.

Preventing routes with certainty

If a segment should never be used for routing, it should not be connected to the road network. For example, Waze may route over railroad, walking trail or stairway segments connected to the road network if conditions are such that the penalized route is still found to be the best route. This is common where there are no alternate routes, such as when Waze finds that the origin or destination is on the penalized segment.