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Routing server

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==Client based When using the Waze application, Waze servers use routing==Calculating an optimal algorithms to determine the best path for a given route at that particular time. The specific details of the routing algorithms used by the Waze server are not publicly disclosed; the following is a difficult taskbased on observation, speculation, and some information revealed by Waze staff. While The operation of the [[client device]] app has routing server is considered to be proprietary and a routing algorithm included, competitive advantage to Waze. The information on this page is not used unless there is no connection subject to the Waze serverchange, and any information that has been revealed may be incomplete or out of date.
==SpeculationClient-based routing ==The Calculating an optimal route is a difficult task. While the client device app has a routing algorithm included, this is not used by unless there is no connection to the Waze server is . Client-based routing only uses cached map tiles. It does not publicly disclosed and the following is based on observationuse real-time traffic data, speculationreports or closures, and some because this information revealed by Waze staff. We can assume that the operation of the routing server is considered to be proprietary and a competitive advantage to Wazenot accessible. We can also assume that Therefore, it is subject to change, and that any information that has been revealed may be incomplete or out of datedoes not provide an ETA.
What has been confirmed is the Waze Map Editor (WME) displays the overall average speed for == Routing requests ==When a segment for each direction of travel through the segment. Also the routing engine uses real-time speeds (from recent Waze app users in front of you when available) and combines the historical speed of the segment broken down into 10-15 minute chunks. Also the time to pass through user requests a segment is tracked separately for each route out of a segment. For example if a segment ends calculation with a left and right turn (no straight let's say)network connection, then the routing engine isolates the time through the segment request is sent to turn left and the time through the segment to turn rightWaze server. This detailed speed information That route is proprietary & is part of then transmitted back to the data Waze sells/plans to sell client device and won't be displayed through the editor.
==Routing The requests==for routing vary according to the settings chosen for the user's account on the client device. Under Navigation one can choose:When you request a route calculation* Whether to allow or avoid [[toll roads]]* Which, if any, [[Carpool, HOV, Transit lanes|toll and HOV]] passes to apply (some segments are permitted only to those who hold the request is sent proper pass)* Whether to the Waze serveravoid {{Ferry|Ferries}}* Whether to avoid {{Freeway|Freeways}}* Whether to allow, never allow, or avoid long unpaved roads* Whether to avoid [[Difficult turn|difficult intersections]] (turns marked "difficult" through nodes or junction boxes).* Vehicle type** {{Passageway}} has a type-specific [[Routing penalty|penalty]]. That route is then transmitted back to your ** [[client devicePartial restrictions|Segment restrictions]] and displayedallow or prevent travel by certain vehicle types.
The requests for routing vary according to the settings you have chosen on your [[client device]]. Under Routing you can choose:* Fastest or shortest == Different route* Whether to allow dirt roads, never allow dirt roads or to avoid long dirt roads* Whether to minimize turns* Whether to [[avoid highways]]lengths ==
The shortest === Pruning ===It is known that the Waze routing engine can't calculate every possible route refers to physical for long-distanceroutes, so it takes shortcuts by removing lower road types from consideration in the middle of longer routes. It This effect is always better to choose commonly called '''route pruning''' and can potentially result in the Fastest route optionchanging dramatically when lengthened slightly. 100km of freeway is better At distances farther than 90km a certain threshold value from the origin or destination of country a route, roadslower than a certain type tend not to be considered. Pruning thresholds with confidential, variable, increasing values exist for {{Street}}, {{Primary Street}} and {{Minor Highway}}, respectively. There is evidence that {{Major Highway}} is never pruned. {{Freeway}} and {{Ramp}} are never pruned. The pruning mechanism uniquely accounts for [[Creating and editing road segments#Special properties|routing road type]], so a Primary Street with routing road type +1 would be pruned at the same threshold as a Minor Highway.
==Missing roads and incorrect junction connections= XL routes ===Generation of routes longer than 1000 miles in Waze tries used to be impossible, but in 2018 a new mechanism for extra-long (XL) routes was put into place. This pieces together multiple long routes to find generate one extra-long route. To save time and avoid routing timeouts, instructions and geometry details are omitted in the middle of the fastest route between you during initial calculation, but they are produced and your destinationlisted later as the user drives along the route. Obviously it Dependent upon multiple factors such as server load and road types, transcontinental routes can only route based on roads be calculated in Waze with this mechanism. It is also evident that it knows about, since XL routes are combinations of shorter routes, the aforementioned pruning behaves differently for them, so your route will not be optimal if a better route does not have all the roads with correct connections that lower road types may appear in the Live Mapmiddle of extra-long routes.
==Real-time current road speeds==We can be confident that Waze The routing server uses real-time reports of current road speeds by preference over (from recent Waze app users if available) and combines the average, historical average road speedsspeed of the segment broken down into 10-15 minute chunks. We know that Waze uses traffic congestion reports The time to reroute around slow trafficpass through a segment is tracked separately for each route out of a segment. Early versions of For example if a segment ends with only a left and right turn, then the routing engine isolates the time through the client would also report when traffic speeds were good - this was removed due segment to map clutter. But Waze will still be receiving this information. We can assume that turn left and the speed of any wazer ahead of you on a stretch of road will be time through the segment to turn right. This detailed speed used when your route information is proprietary and is calculatednot displayed in the Waze Map Editor.
As the number and density of wazers grows this It is known that Waze prefers to use real-time data takes on a greater importancereports of current road speeds over historical average road speeds. Waze also uses traffic congestion reports to reroute around slow traffic. This emphasis is partly a reflection <!-- Early versions of Waze's original goal the client would also report when traffic speeds were good - this was removed due to optimise commutesmap clutter. As But Waze has grown to will still be used as receiving this information. -->The speeds of recent Wazers traveling on a more general purpose GPS navigation device over roads less travelled, road will be factored into the route given to subsequent Wazers traveling on the historical average same road speeds becomes more important.
Since Waze uses As the time you expect to be at a road segment to calculate the expected speed on that segmentnumber and density of Wazers grows, it cannot use this real -time data when you trip time moves into takes on a future time slotgreater importance. So trips of more than 30 minutes (and on average more than 15 minutes) will include future time slots where current traffic data This emphasis is not available. When you enter partly a new time slot, real-time traffic data may be available which may cause your client reflection of Waze's original goal to recalculate your ETA and reroute youcreate optimal commutes.==Fastest routing==As Waze knows has grown to be used as a more general-purpose GPS navigation device over roads less traveled, the historical average speed of every confirmed road between you and your destination. The Waze server can calculate which list of roads to take to minimize the total travel timespeeds becomes more important.
While every request is processed in real-time, by observation it appears that Since Waze [[glossary|caches]] some requested routes or major points. This means if it already knows uses the best route from B to C, and you ask for future expected time of arrival onto a route from A road segment in order to C, it may just calculate the best route from A to Bexpected speed on that segment, once it checks that there isn't a better route bypassing B altogethercannot use real-time data too far in the future. So longer trips (on the order of 30 minutes or more) will include future time slots where current traffic data is not available when initially calculated. This does mean As the trip progresses, any real-time traffic data that when there is a [[Timeline of updating process|Live map update]] some routes may be less than optimal for up available causes the client to a day as routes are cached recalculate the route and recalculatedthe ETA.
While a complex calculation== Average road speeds ==If the average or historical road speed is not correct, calculating then the route may not be optimal route . However, deletion of segments to reset average road speed is possiblenot recommended. The complexity arises over Waze uses the data from Wazers traveling through the segments to update the "average speed" , and oftentimes an anomalous historical road speed is automatically corrected with further data collection. If Waze appears to disfavor the use of the roadscertain segments along a route, a number of other reasons can cause such a situation.
==Changes in route due to different [[glossary|origin]]= Time-of-day variations ===Consider calculating a route from A to Zroad that most Wazers drive at 5 PM when the average speed is 12 MPH. The suggested route may be A At 10 AM when the road is clear and the average speed is 60 MPH, it is the best road to B to C to D to Ztake. Then calculate If Waze only has historical speed data from 5 PM, it will assume that the route from B to Z. You speed of the road is 12 MPH all day, and it may get a suggested route of B to C to E to Znot recommend this road. At first glance, As more people drive this suggests one road closer to the time of day when a given route is not optimalrequested, Waze will get a better guess for the average speed at that time.
We can guess === Shrinking window ===If there are enough recorded speeds on a road, then Waze uses a shrinking window of speeds to better estimate the average speed at what might be happeningthe current time. There may be a problem associated with Waze uses the possible caching speed of routeseach road segment (in both directions) in intervals as small as 30 minutes. Or So a two-way road might have up to 96 average road speeds in a day. It can be assumed that when there may be are insufficient records for an individual time slot, a "timing window" effect. The different arrival wider time at C may change the best route range is used (up to Za full day). Or there may be a fine tuning effect in As the routeroad is driven more at different times, perhaps to avoid too many turnsthe time slot shrinks. So by dropping Additional information is used based on the segment A to B, day of the segments C to E to Z week. There is no longer exceed some thresholdevidence that Waze records speeds for larger date ranges such as months or seasons; however, it will update its average speeds relatively quickly when seasonal traffic patterns change.
This effect can be observed while driving. If you recalculate Waze uses the average road segment speed for the time slot that applies at the time when a route user is expected to a destination while driving arrive at that road segment. Because of this time window, Waze suggests different routes at different times of day. This is dependent on how many times are recorded on the roads along an already calculated the route to that . If they're all recorded at about the same destinationtime of day, then the route may changetime window does not help. If 1,000 times are recorded at about 5 PM and 2 times are recorded at 10 AM, then the 10 AM average speed still is based mostly on times from around 5 PM.
This are old reports where wazers have not offered === Turn delays ===On a route to bypass heavy trafficsegment of a road, but do receive a new route when manually asking for it. It may user's average speed can be they would have been offered that alternative route very different depending on what is done at that point anyway, whether or not there was bad traffic ahead. It does raise the question as to when and how Waze considers rerouting, but these may have been addressed in end of the current versionsegment. Certainly Waze does offer new routes sometimesTraffic going straight through a traffic light might go very fast while traffic turning left might wait a very long time. A freeway exit lane might go fast while traffic continuing hits congestion.
==Changes in routes due [[Image:SegmentTraffic1.png|right|350px]]Waze has the ability to separately track the average speed of traffic that passes through a segment, but exits to different route lengths==segments. The routing engine takes this into account. In the diagram, multiple times are tracked for traffic flowing through Seg4 based on the segments to which it exits. There are then two average drive times for:
In addition, it is known that the Waze routing engine can't calculate every possible route for long distance routes, so takes shortcuts for longer routes, potentially resulting in the route changing dramatically when lengthened slightly. According * Seg4 to Waze support (as of July 2011), the section of a route more than 10 km from each endpoint is heavily weighted towards non-streets (i.e. "Primary Streets" or the various Highway types). My personal guess is that it simply ignores streets outside of the 10 km radius from the endpoints when doing its calculations Jnct2 to speed up the calculation. The specific quote from support was: "Above some distance (currently 10KM) from both end points (start and destination) the server prefers to go through non streets. Now as it happens here - this small distance was the difference between being less than or over 10KM. Now the penalty of going through a street in this case is high - so the server prefers the highway." In this particular case, the observed behavior was that extending the route by a short distance caused Waze to suggest a very different (and much longer, both in distance and estimated time) route.Seg5
==Problems with average road speeds==If the average road speed is not correct, then the route will not be optimal. The following are reasons why using the average road speed can be the wrong value * Seg4 to use.Jnct2 to Seg6
===Time of day variations===Consider a road Traffic building up on Seg4 that most wazers drive at 5pm when turns right to Seg6 does not affect the average speed is 12 mph. You choose your route at 10am when timing for the road is clear and the average speed is 60mphtraffic also using Seg4, but instead turning left to Seg5. It For this reason it is the best road important to take, but Waze chooses a different route because it has no information about the speed keep long segment lengths before junctions as traffic congestion at 10am and assumes the speeds is 12mph all dayjunction might affect exits differently.
You canTo understand this problem better, consider if we add a short Seg8 between Seg7 and Jnct4. Let's say the traffic exiting Seg10 backs up all the way to Seg7 (easy enough, of coursesince Seg8 is short). Because Seg7 only has a single exiting segment (Seg8), drive the road yourself, and Waze will eventually learnrouting server is only able to collect a single average speed &mdash; it can no longer distinguish traffic by where it is going ''after'' Seg8. We do not know how many times Now the through traffic going to Seg9 appears to Waze uses to slow down through Seg7, even though it doesn't in its calculationreality. However if Waze does discard old time informationAt a minimum this causes an incorrect ETA for routing, you may not accumulate new time faster than and it is discardedmight actually cause traffic to be rerouted unnecessarily, and less optimally, through another route. It Hence, if there is also possible a chance that your times are being ignored as being abnormaltraffic can go in different directions at a junction and that junction can experience different amounts of congestion, the segment before the junction should be kept long, or a [[junction box]] may be used.
More === Outdated and abnormal road speeds ===Average speeds can change over time, and recorded times can be abnormal or wrong—and can stay wrong for a very long time. This may be due to users recording inaccurate speed data by doing things like walking, biking or sitting in their driveways with Waze users would help fix thisopen. Also, if [[Segment length|segments are less than {{:Segment length/Minimum}}]] they may not be long enough to record accurate transition times. There is some evidence that abnormal road speeds and old road speeds are discarded, or at least not used in calculating the average speeds of roads.
===Turn delays=Recalculation ==Consider a road When Waze receives notification of length 1 mile where you drive straight ahead and go through traffic conditions, it uses the intersection all at 100mph taking 36 seconds. Or at the end actual speed of roads on your route, rather than the road you can sit and wait 5 minutes to make a turn. In the first case your average speed . This is 100mphbased on [[Real time closures|real-time closures]] and automatic traffic condition reports - light, moderate, heavy traffic or complete standstill. In the second case your average speed is just under 11mphManual reports of traffic jams and accidents are for display only and do not change routing.
Now if 9/10 wazers go straight through, the average road speed ETA is 91 mph. Waze will recommend this route, even if if involves updated in response to a turn user's progress on your the routeand in response to these real-time traffic conditions. If real-time traffic conditions make the given route significantly worse than alternatives, and Waze may provide an automatic recalculation. The benefits of this are balanced against the perceived hassle of changing one's route is not optimal.
Contrariwise, if 9/10 wazers make that 5 minute turn, the average road speed is 20mph, and even though your optimal route would take you straight through at 100mph, Waze will not suggest it because it sees the average speed as 20 mph.  We can assume Waze is aware of this issue. You can choose the Minimize Turns option in your Routing settings. Or you can use your own discretion. The good news is that by collecting your route information Waze is collecting enough information to give correct routing advice when it implements it. It knows the average speed of people going straight through and it knows the average speed of people making the turn. And it can apply the correct average speed when calculating your best route. It make the calculation more complex, but it can be done. At the moment it is not being done. ===Waze Map Editor changes===The average speed of a road can be dramatically altered by editing in Waze Map Editor (WME). Consider a 50m length of road driven in 36 seconds. An editor extends this length of road the full 10km length. WME now records this road as 10km long, but also driven in 36 seconds for an average road speed of 1000km/hour. Therefore be cautious of significantly changing the length of roads. Instead consider drawing new roads and linking them. ==Traffic lights and stop signs==
Waze does not record the location of traffic lights. While some GPS navigation offers guidance like "turn right at the next traffic light" the information is frequently incomplete, incorrect or outdated. The consensus view is that Waze should not record the location of traffic lights.
Waze does take traffic lights and stop signs into account by noting the effect they have on traffic speed. Consider a traffic light with long waiting times. The road segment leading to that traffic light will have a low average speed. If the average speed (based on the average waiting time) becomes low enough, a longer route that avoids the light will become becomes the preferred route. This has been observed in practice and is an example of ''emergent behaviourbehavior''. Waze isn't programmed to avoid traffic lights but it will does avoid slow roads; if the traffic lights make the road slow then Waze will avoid avoids them. Some drivers will regularly take longer routes—even winding through side streets—to avoid any stops or traffic lights. Waze has been known to suggest this, and also known to revert back to waiting at lights when better average speed information is collected from the side streets. But note that this can be less than optimal due to the turn delays discussed above. ==Outdated and abnormal road speeds==Road conditions change, construction work comes and goes, and average road speeds can change dramatically. One day you may be stuck behind a truck, and another day you may be crawling along the roads at 2 a.m. transporting your pet goldfish. Or your GPS might have a glitch and show you travelling at 1,000 mph. In short, average speeds can change over time, and recorded times can be abnormal or just plain wrong—and can stay wrong for a very long time. We can assume Waze is aware of this. There is some evidence that abnormal road speeds and old road speeds are discarded, or at least not used in calculating the average speeds of roads. ==Average road speed "shrinking window"==If there are enough recorded speeds on a road, then Waze uses a shrinking window of speeds to better estimate the average speed at the time you are travelling on it. Waze uses the speed of each road segment (in both directions) in intervals as small as 30 minutes. So a two-way road may have up to 48 average road speeds. We can assume that when there are insufficient records for an individual time slot, a wider time range is taken—up to a full day. As the road is driven more, the time slot would shrink down to 30 minutes. We can speculate that there may be additional information used that is based upon the day of the week. There is some observational evidence that a road that is busy on weekdays and not used for routing will be chosen as the optimal route on weekends. At some point, Waze would also need to consider the months of the year as seasonal variations can affect the speed of the roads. Waze uses the average road segment speed for the time slot that applies at the time you are expected to arrive at that road segment. Because of this "time window", Waze will suggest different routes at different times of day. This is dependent on how many times are recorded on the roads along the route. If they're all recorded at about the same time of day, then the time window will not help. If 1,000 times are recorded at about 5 p.m. and 2 times are recorded at 10 a.m., then your 10 a.m. average speed will still mostly be based on times from around 5 p.m. ==Routing algorithm refinements=====Routing options===It's easy to see how routing options can be implemented. For example, to minimise turns we can add a time penalty for fastest routing or a distance penalty for shortest routing, when calculating the fastest or shortest route.  ===Junction penalties===Currently Waze applies a five-second time penalty when calculating a route that passes through a junction. While not an unreasonable approach to dealing with intersections, it has generated some flawed routing and is being reviewed.  One major issue arises in long highways which may be made up of hundreds of segments connected together, as this may add a penalty of as much as five minutes to a trip, even though the intersections are not real. This supports the arguments of those who aim to have a clean edit of maps where junctions are only used when necessary. In practice, we need to deal with the map as it stands. An automated tool to remove the junctions is needed as the manual work that is required is enormous. The routing problem can be fixed in a variety of ways. One could:* Not apply the penalty when there are no other existing roads meeting at the junction;* Not apply the penalty when you cross a junction onto a road with the same name;* Not apply the penalty when the road you are travelling on is a higher class (e.g. highway versus street, primary street versus street), where we can assume the higher class road has the right of way; or* Not apply the penalty at all when travelling on freeways, motorways and highways. Even if a road is correctly connected with no unnecessary segments, the junction penalty can still give incorrect results. For example a busy highway may be correctly connected to the ramps along its length. A quiet country road running in parallel may not have all the minor connecting roads recorded; it looks like a straight section of road with no junctions. Waze may choose the country road as the preferred route because of the lack of junctions. ==What to do if you think the generated route is wrong==Firstly, use the option to generate alternative routes. This may give you some clues as to why Waze is offering that route. Secondly, if you think there is a better route, check in Cartouche that the roads are all connected along the route.
ThirdlySome drivers regularly take longer routes — even winding through side streets — to avoid any stops or traffic lights. Waze has been known to suggest this, post a message detailing the problem route - origin, destination and a Cartouche permalink also known to revert to waiting at lights when better average speed information is collected from the [http://wwwside streets.waze.com/forum/viewforum.php?f=6&sid=2872533f5796ac39dc6747511398e907 Navigation forum]. Other eyes will check it, and you may indeed find a flaw in But note that this can be less than optimal due to the Waze routing algorithm. Fixing it may make it better for everyoneturn delays discussed above.
==Change of RoutingWhat to do if you think the generated route is wrong ==When # Use the option to generate alternative routes. This might give you some clues as to why Waze receives notification of traffic conditions it uses is offering that route.# If you think there is a better route, check in the actual speed [[Waze Map Editor]] that all of its roads on your routeare connected, rather than and all legal turns are allowed.# Communicate the average speedproblem. This is based only Possible means of communication include:#* Report a [[map issue]] in the app and respond to comments on it.#* Post a message detailing the automatic traffic condition reports - lightproblem route (origin, moderate, heavy traffic destination and a WME permalink) to the [http://www.waze.com/forum/viewforum.php?f=6&sid=2872533f5796ac39dc6747511398e907 Navigation forum] or complete standstillyour state's local forum. Manual reports of traffic jams and accidents are for #* Join your local community's Waze Discord server (accessible from your information only and do not change routingstate wiki page). This will usually produce the fastest response from local editors.
It may be == You are the driver ==Waze can never see that even with the traffic reports, there light is green going straight or know that today is a public holiday. It can offer you guidance as to what is no better the best route under average conditions. But you are the driver and Waze will not offer you oneare in the best position to make the decision for today under today's conditions.
==You are the driver==If everyone followed Waze directions and never drove on a new route, Waze can might never see learn that the traffic light route is better. When Waze is green going straightrecording your travels, or every trip helps make Waze better for everyone. That includes when you think you know that today is a public holidaybetter. Sometimes you will be right. It can offer And sometimes you guidance as to what is the best route under average conditionswill be wrong. But it is better to find out you are wrong so you can choose the driver and better route. And when you are in right, all Waze users benefit by the best position to make the decision for today under today's conditionssharing of your knowledge.
If everyone followed [[Category:Waze directions and never drove on a new route, Waze may never learn that route is better. When Waze is recording your travels, every trip helps make Waze better for everyone. That includes when you think you know better. Sometimes you will be right. And sometimes you will be wrong. But it is better to find out you are wrong so you can choose the better route. And when you are right, all Waze users benefits by sharing in your knowledge.operations]]
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