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From Wazeopedia

Detour Prevention Mechanisms

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Notes: some minor changes
* Be careful of "false positives!" For example, where route number concurrencies concurrences begin and end, the big detour prevention mechanism may be unexpectedly triggered as follows (see diagram):
** In a concurrency, two highways share the same road, and both names will appear on the concurrent segments, using [[alternate names]]. Where the concurrency ends, the two highways split into separate roadways again.
** Often, there are ramp segments connecting the last concurrent segment to one or both of the non-concurrent continuations. If the concurrency was of I-1234 and I-4567, for example, there might be a ramp named "to I-1234 / Sometown" - a name which contains "I-1234" but is not identical to the highway name.
** To prevent this, just assign I-1234 as an alternate name to all ramps between the two sections (concurrency and continuation). Note that if there is only a single ramp segment connecting the highways, there will not be a "false positive." Nevertheless, it is a good practice to do this even for a single ramp segment, in case the ramp is cut into two segments later, either by accident or because later construction or map improvements connect another feeder ramp in the middle.
* Another example of a false positive could occur where a highway has multiple wayfinders connected , one to another , (for example, if there are several multi-lane exits in a row).
[[File:AltNameDetour.jpg|border|center]]
== {{Anchor|Small Detours}}{{@|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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