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Detour Prevention Mechanisms

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Removed the double decleration of the word "that" in the first sentence of Small Detours subsection.
== <!--if the section parameter is defined, do not place the visible banner, only as the code block for the top of a section-->{{@|Big DetoursGlobalMark/visible}} ==Waze routing includes a big detour prevention (BDP) mechanism to prevent routing off a highway/freeway only <!-- #####-----#####-----#####-----#####-----#####-----#####-----#####-----#####----- #### This page has been curated #### #### to be routed right back on included in the same highway/freewaynew #### #### Wazeopedia - GLOBAL Wiki. The assumption is that drivers will prefer to remain #### #### Please do not make any #### #### edits on this page without #### #### PRIOR CONSENSUS in the highwayWiki #### #### Updates and Discussions #### #### forum thread for this page. #### #### If a specific forum thread #### #### for this page doesn't exist #### #### please start one. #### #### www.waze.com/freeway even if Waze calculates that taking a series of ramps or other collectorforum/distributor roads is slightly faster or shorter #### #### viewforum.php?f=276 #### #####-----#####-----#####-----#####-----#####-----#####-----#####-----#####-->
=== {{@|Criteria}} =Big Detours==Waze routing includes a mechanism to prevent routing off a highway/freeway only to be routed right back on the same highway/freeway. The assumption is that drivers will prefer to remain on the highway/freeway even if waze calculates that taking a series of ramps or other collector/distributor roads is slightly faster or shorter.
:A {{u|"possible detour"}} is a series of segments in Waze routing will reduce the middle chances of a route which meet the minimum criteria to trigger an evaluation.:A {{u|"detour"}} is defined as a portion of off a route which meets highway/freeway and back on that same highway/freeway when '''all''' of the criteria listed following conditions are met:# All highway/freeway segments including the last one before and the first one after the detour need to have the same (alternative) name. (Don't mix those.); unnamed segments are not considered as having the same name# the detour is more than one segment long, and# the detour is under the threshold length as defined below.
Possible detours are evaluated to determine if they meet '''ALL''' the following criteria, and are penalized if they do.
'''NOTE:''' If the continuation path we wish Waze to use also meets the below criteria it will be equally penalized, cancelling the BDP effect.
 
#'''Road Name Discontinuity''' - The freeway/highway segments immediately before and immediately after the possible detour must share at least one street name (either segment may have the shared name as either a primary or an alternate name). {{u|The possible detour must include at least one segment (including the last segment of the possible detour) that is missing this shared street name (as both a primary name and alternate names).}}
##No Other Continuous Name - {{u|The possible detour segments must ''not'' all share any other street name with the both the freeway/highway segments immediately before and immediately after the possible detour.}}
#'''Road Type Discontinuity''' - The freeway/highway segments immediately before and immediately after the possible detour must be from the same 'Road Type Group' as defined in the chart below. {{u|The possible detour must include at least one segment not in that same 'Road Type Group.'}}
#'''Existence Of Direct Route''' - The BDP mechanism is intended to penalize detours away and back to a direct route. The following two criteria are used to determine if there may be a possible direct route.
##Existence Of Alternate Route - {{u|There must be an alternate route connecting the freeway/highway segments immediately before and immediately after the possible detour which bypasses the segments of the possible detour.}}
##Alternate Road Type Continuity - {{u|The freeway/highway segment immediately after the possible detour must be accessible from another segment of the same road type group.}}
#*''The BDP mechanism does not determine that there is actually a direct route with name and type continuity, but rather only uses the above two criteria.
#*''Thus, the alternate route may be a detour itself. The alternate route need only use different segments than the possible detour being evaluated.
#*''If the first segment after the possible detour is the beginning of a freeway or highway and, thus, can only be accessed from ramps, or segments of a different road type group, it is assumed that there is no direct route.''
#'''Minimum Length''' - {{u|The possible detour must be more than one segment long.}}
#'''Maximum Length''' - {{u|The possible detour must be shorter than the threshold length as defined in the chart below.}}
 
 
<center>
{| class="wikitable"
|-
! Road Type Group!! Threshold
|-
| {{Freeway}}<br />|| 5km|-| {{Major Highway}} || 5km
|-
| {{Minor Highway}} || 500m
|}</center> 
It is important to understand that Waze uses a [[Routing penalties|penalty-based]] routing system. It computes the total penalties for a route and selects the one with the least cumulative penalty. Therefore it is possible for big detour routes to occur when the primary route is extremely slow.
=== {{@|Notes}} ===* For divided roadways that have the same name on both carriageways, the big detour prevention mechanism will prevent U-turns that traverse more than one segment. Thus in the intersection below, the configuration on the left will be used to route a U-turn because it uses a single segment between the two parallel roadways with the same name. In contrast, the configuration on the right will '''not''' use the U-Turn road because it branches from another segment causing multiple segments between the two parallel roads with the same name, and the U-turn is not in the same Road Type Group.
[[File:UDetour.png|border|center]]
[[File:AltNameDetour.jpg|border|center]]
== {{@|Small Detours}} ==Waze has a small detour prevention mechanism to deal with instances where Waze calculates that that a left turn can be "optimized" by using U-turns and right turns (either continue straight, U-turn, right turn; or alternatively, immediate right turn, U-turn, continue straight). While this may save a few seconds over waiting for a long average left turn, it is undesirable. Waze will prevent such detours if there is not a measurable difference in the route times. The exact difference in time required to trigger this prevention is proprietary, and subject to change as needed.
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