"Ghost traffic jams"

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Re: Re:

Postby gettingthere » Fri Mar 30, 2012 9:12 pm

jasonh300 wrote:If this was the case, you'd never get a jam anywhere in a dense downtown type area where the blocks are only 100 m. Or maybe my idea of 100m is distorted.

How big is a city block?


100 meters is about average.

Yep, that's part of the issue with this type of filter. Valid traffic information is filtered out to try to deal with Wazers who are running the application when they are not driving with the flow of traffic.

I don't know if you ever noticed, but nearly everytime I run into a traffic jam on a freeway, the speed that Waze has posted seems to be a bit higher than the speed that the traffic is actually moving. Very difficult to eyeball it though. Could be that the 50 meters of data that is discarded is falsely inflating the traffic speed in every segment.

Think about base mapped segments that are loaded with extra, invalid junctions. Every segment between junctions could be discarding valid speed/traffic data.

Disclaimer - The actual algorithms that Waze is using have not been fully disclosed by Waze and/or may have changed.

http://en.wikipedia.org/wiki/City_block
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Re: Re:

Postby CBenson » Fri Mar 30, 2012 10:34 pm

jasonh300 wrote:
jenncard wrote:I forgot about that. There is an "understanding " that no jams are created at 50 meters around a junction, right


If this was the case, you'd never get a jam anywhere in a dense downtown type area where the blocks are only 100 m. Or maybe my idea of 100m is distorted.

How big is a city block?

Yeah, I suspect what is meant is not 50m within a junction, but rather from the slowest 50m of the segment. Jams are certainly generated in downtown DC. And they are typically shown when the traffic is backed up for the entire block.
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Re: "Ghost traffic jams"

Postby phil_whiteboy » Mon Apr 02, 2012 10:01 am

Sometimes the simplest solution is the best...

How about no automatic computations of traffic jams? There is a report traffic button already on the client so why not let us use it? If someone clicks the report traffic then gladly slap the average speed on that segment of reported road. But if no one has clicked the button then why try to automatically detect traffic? I know the developers want to show off their toys of what is possible, but sometimes you can be too smart for your own good.

Simple fix, no automatic, if im stuck in traffic i will push the button. Done, hours of labor and wages saved from debugging efforts. Put that energy into something else we can benefit from.

BTW: In the wiki is said a pause button would be added in v2.2 however im using v3.1 and still do not see a pause button. However i still think waiting to push the traffic button is better then to always push a pause button every time i stop. It would get to be annoying as i will stop and go more then i hit a traffic jam.
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Re: "Ghost traffic jams"

Postby AlanOfTheBerg » Mon Apr 02, 2012 2:54 pm

They decided against a pause mode and the automated traffic jams, assuming they are working 100% correctly; big assumption I know :), are better for the end user, safer, and legal. Even touching your screen when stopped on the side of the road, not even in traffic, is illegal in some places, and likely more to come.
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Re: "Ghost traffic jams"

Postby gettingthere » Mon Apr 02, 2012 3:16 pm

Yes, Waze needs to focus on the automated jams and get everything fixed. We should not have to press anything to affect traffic reporting. In fact, a good argument is that the manual traffic report function could be removed if the automated jam system is further optimized.

As posted many times in other threads, limitations/problems with the current system:

* Jams are not filtered well enough. One Wazer not travelling with the speed of traffic should not be able to create/clear/affect a jam. Either a Wazer who is stopped on the side of the road, a Wazer on a train, a Wazer attempting to make Waze work as a pedestrian, a Wazer on a motorcycle blowing by traffic, or a Wazer in a car pool lane that is snapped to the freeway clearing jams on the freeway.

* The current filtering system is likely discarding valid traffic. (slowest 50 meters of traffic being disregarded for each segment - if still a filter that is in use)

* As well as the recently reported issues with jams - routing not affected by very slow jams or very slow average segment speeds, ETA not correct, alternative routes ignoring traffic, traffic showing correctly but then you set a new route or look at alternatives and the traffic is ignored.

* The traffic event preview screen when setting a route or looking at alternative routes needs to be fixed. Often it doesn't show the correct data.

Basically Waze needs to consider all traffic but also needs a better way to filter out invalid data.

So since we still have no reply from Waze - we still don't know what they are looking for in regards to this thread.
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Re: "Ghost traffic jams"

Postby dirgela » Mon Apr 02, 2012 6:42 pm

gettingthere wrote:* Jams are not filtered well enough. One Wazer not travelling with the speed of traffic should not be able to create/clear/affect a jam. Either a Wazer who is stopped on the side of the road, a Wazer on a train, a Wazer attempting to make Waze work as a pedestrian, a Wazer on a motorcycle blowing by traffic, or a Wazer in a car pool lane that is snapped to the freeway clearing jams on the freeway.

It would be kind of stupid to have several wazer go through the traffic to show it for the others. When there are enough data to validate the traffic it might be already over :lol: Remember that the purpose should be to avoid the traffic and not to report it, so I'd say better a false positive than a false negative. It is the worst what can happen with the app that claims to let you avoid traffic to see how it happily navigates you through the traffic (I am not even talking about the cases when the road is already marked as having close to zero speed and that is ignored by waze).
The fully automated reports are just a hallucination - for it work there so many "musts" that it will never work (like "enough wazers", "roads with no errors", "routing server working properly" etc.)
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Re: "Ghost traffic jams"

Postby phil_whiteboy » Mon Apr 02, 2012 7:13 pm

Sure in a perfect world that is black and white, you can define it with ridged conditions. However since the world is not black and white and there are soo many what-ifs and variables involved, i do not believe you can create a traffic system based on a single moving device. Cities that offer automated traffic reporting do so with fixed locations monitoring multiple vehicles passing defined points.

True it would be nice, and it would be considered safer for drivers to have it 100% automated. But so would world peace and solving hunger. However just because we wish it doesn't mean there is a simple or practical solution to it.

I am willing to state for the record, it is impossible to automate accurate traffic reporting based on a single device as there is not enough known information. There are too many variables and it would require reporting from multiple sources.

Do they track GPS with a single satellite? See my point? I know you don't want to accept it, but it doesn't change the physics / facts of the matter. Just give it up, let it go... :)
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Re: "Ghost traffic jams"

Postby AlanOfTheBerg » Mon Apr 02, 2012 7:27 pm

phil_whiteboy wrote:I am willing to state for the record, it is impossible to automate accurate traffic reporting based on a single device as there is not enough known information. There are too many variables and it would require reporting from multiple sources.

Do they track GPS with a single satellite? See my point? I know you don't want to accept it, but it doesn't change the physics / facts of the matter. Just give it up, let it go... :)

The physics of triangulation are wildly dissimilar to traffic flow, but your point about accurate traffic reporting with a single device is correct and I agree with it.
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Re: "Ghost traffic jams"

Postby phil_whiteboy » Mon Apr 02, 2012 7:47 pm

AlanOfTheBerg wrote:The physics of triangulation are wildly dissimilar to traffic flow, but your point about accurate traffic reporting with a single device is correct and I agree with it.


Yes, triangulation is dissimilar to traffic flow. I was making the point that you can not predict movement of an object (traffic) based on a single point (one device) without any known variables of that single point in relation to that object.

I just wanted to throw in the GPS example in the hopes that the developers might actually read this some day and realize although well intended the concept is not practical. They should solve the issue by thinking of a new method, and not just trying to tweak their current method.
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Re: "Ghost traffic jams"

Postby gettingthere » Mon Apr 02, 2012 9:27 pm

As we understand it now, ONE Wazer's movements can define, update or remove traffic jams in Waze. Yes, this is highly subject to error and a bad way to measure traffic.

Of course this is why we see false traffic jams all over the map.

If Waze cannot generate enough data via Wazers and wants to have a viable solution, Waze needs to partner with another provider who has enough flow rate data to more accurately reflect the traffic conditions.
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