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The Waze routing servers use a system that penalizes routes if they meet certain conditions or contain certain elements. Penalties are measured in extra time added to the route, on top of the calculated time that driving the route is expected to take. This extra penalty time does not affect the estimated time of arrival, so it is invisible. When multiple routes are compared, however, the penalized route may not be offered, because the invisible extra time makes it look like it takes longer than a non-penalized slower route.
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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 ==
== Background ==
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The following segment properties cause routing penalties:
The following segment properties cause routing penalties:


*[[Map Editing Quick-start Guide#Turn restrictions .28allowed turns.29|Turn restrictions]] and [[Scheduled restrictions#Turns|scheduled turn restrictions]] during the designated time for the designated vehicle type.
*[[Soft and hard turns|Soft restricted turns]] (red arrow with a purple question mark)
*[[Creating and Editing street segments#Set Road Type.2C Direction.2C and Elevation|One-way roads]] against the designated direction of travel and [[Scheduled restrictions#Segments|scheduled segment restrictions]] for the designated time for the designated vehicle type.
*Soft allowed turns (green arrow with a purple question mark)
*[[Road types#Non-drivable|Non-drivable road types]] including Walking Trail, Pedestrian Boardwalk, Stairway, Railroad and Runway/Taxiway.
*[[Best map editing practice#Toll roads|Toll roads]] for clients with avoid toll roads selected in the app
*[[Best map editing practice#Toll roads|Toll roads]] for clients with avoid toll roads selected in the app.
*[[Creating and editing road segments#Special properties|Unpaved roads]] for users with "don't allow unpaved roads" selected in the app, or when segment length exceeds 300m with "avoid long ones" selected
*[[Road types#Dirt|Dirt road/4X4 Trail]] for clients with "don't allow" selected in the app, or when segment length exceeds 300m with "avoid long ones" selected.
*[[Road types#Parking Lot Road|Parking lot roads]] and [[Road types#Private Road|private roads]] when transitioning '''from''' one of these two road types '''to a different road type'''.  Not when entering these two road types. This is discussed in detail in [[Private Installations]].
*[[Road types#Parking Lot Road|Parking lot roads]] and [[Road types#Private Road|private roads]] when transitioning '''from''' one of these two road types '''to a different road type'''.  Not when entering these two road types. This is discussed in detail in [[Private Installations]].
*[[Road types#Passageway|Passageways]] for all vehicle types except motorcycle
*[[Road types#Freeway|Freeways]] for users with "avoid freeways" selected in the app
*[[Partial restrictions#Difficult turn|Difficult turns]] for users with "don't allow difficult turns" or "always reduce difficult intersections" selected in the app


== Road configurations ==
== Road configurations ==
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*[[File:OffOnFreeway.png|border|390px|right|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]].
*[[File:OffOnFreeway.png|border|390px|right|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]].
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* When a new node is created along a current or new segment, the node will default to a 5 second penalty through that node until someone drives across it and the [[map tiles]] are rebuilt with the new data. After that point the 5 second penalty is removed and the measured transit time through that node is used.


== Preventing routes with certainty ==
== 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 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.
The following conditions prevent routing and do not involve penalties:
* Closure
* Hard turn restriction
* Time-based turn restriction (depending on whether conditions are met)
* Time-based segment restriction (depending on whether conditions are met)
* Non-drivable road types
* Wrong way of a one-way road
* Disconnection of one road from another
* Deletion of a road


In the past, many of these conditions created penalties and could not prevent routing with certainty, so disconnection and deletion were necessary. [[Real time closures#Deciding when to use an RTC|This table]] explains the various uses and trade-offs of routing prevention methods.
[[Category:Waze operations]]
[[Category:Waze operations]]

Revision as of 12:44, 30 May 2019

The Waze routing servers use a system that penalizes routes if they meet certain conditions or contain certain elements. Penalties are measured in extra time added to the route, on top of the calculated time that driving the route is expected to take. This extra penalty time does not affect the estimated time of arrival, so it is invisible. When multiple routes are compared, however, the penalized route may not be offered, because the invisible extra time makes it look like it takes longer than a non-penalized slower 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:

  • Soft restricted turns (red arrow with a purple question mark)
  • Soft allowed turns (green arrow with a purple question mark)
  • Toll roads for clients with avoid toll roads selected in the app
  • Unpaved roads for users with "don't allow unpaved roads" selected in the app, or when segment length exceeds 300m with "avoid long ones" selected
  • Parking lot roads and private roads when transitioning from one of these two road types to a different road type. Not when entering these two road types. This is discussed in detail in Private Installations.
  • Passageways for all vehicle types except motorcycle
  • Freeways for users with "avoid freeways" selected in the app
  • Difficult turns for users with "don't allow difficult turns" or "always reduce difficult intersections" selected in the app

Road configurations

Other routing penalties are based on road configurations.

  • Segment too short to allow two left turns
    Segment too short to allow two left turns
    Waze will penalize a route (which forms a U-turn) 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. The specific details on configuration, and criteria for this penalty are documented in the Intersections page of the Junction Style Guide.
  • Ramps should prevent detour
    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

The following conditions prevent routing and do not involve penalties:

  • Closure
  • Hard turn restriction
  • Time-based turn restriction (depending on whether conditions are met)
  • Time-based segment restriction (depending on whether conditions are met)
  • Non-drivable road types
  • Wrong way of a one-way road
  • Disconnection of one road from another
  • Deletion of a road

In the past, many of these conditions created penalties and could not prevent routing with certainty, so disconnection and deletion were necessary. This table explains the various uses and trade-offs of routing prevention methods.