"Ghost traffic jams"

[fvwazing]

Yep, I think shirlig means "false positives" here. Typically caused by a mixture of keeping the car matched to the original route instead of the neighboring parking/gasstation, not recognizing that the car is paused and not just slow, and ignoring the answer to the "Are you in traffic?"-question. The ones that I coined "phantom-jams" (as in this thread or this one) are much rarer and they are definitely not "caused by your driving session".

I am flattered by that we are asked, but also puzzled - these jams are theme of 100s of threads on the forum, they can be provoked anytime, anywhere. Why ask? Just stop at a gasstation on the way to the WazeHQ and you have won a jolly day of debugging.

Sometimes, I think those "phantom-jams" reveal a sinister aspect of the algorithm - starved of data during certain quiet intervals of the day, the artificial Waze-intelligence DREAMS of jams, big jams, long jams, slow jams, dark bloody red jams...

[fvwazing]

Hey, nobody said it would be easy. Add to all that the brownian movement caused by a GPS-inaccuracies and you see a fine mess...

However, if I switch navigation OFF when I am in a gasstation next to the freeway my car-icon - glued to the freeway at first - jumps to the correct location and no jam occurs. So, maybe it is enough to use the improved accuracy that the latest generation of smartphones have, and combine that with a bit of heuristics (as in: "if I am standing still BETWEEN a freeway and a parking, chances are higher that I am standing still ON the parking.")

Good to see things are moving in this field, I may generate 1 or 2 of my favorite jams tonight and send them in.

[fvwazing]

...or throw in the "Are you in a car, experiencing traffic?" in case there is doubt that the trafficreport that is about to get generated is a valid one. Answer can be via voicerecognition ("yes" is yes, silence or "no" or "humhum" is no) and only a positive answer publishes the event. All other cases automatic.

Would beat most of the false alarms and even more important: on experiencing/recognizing a false alarm every wazer could assume there is a human playing the system and not the system playing us humans.

[fvwazing]

I think this was the intent with the 'are you in traffic prompt'. But that is a failure since that does not stop an automated traffic report from being generated. It only allows the Wazer to post a manual report which then makes the automated traffic reporting mechanism 'more sensitive' or 'gives it double weight' to being created.

No - wasn't their intent. Waze is allergic for manual intervention in trafficreportgeneration.

[fvwazing]

Today i was playing pac-man in a residential area. There were aprox 10 streets with dots so i was tracing over them. About half of the streets where auto marked traffic with average speeds of 25km.

With this being the average speed limit in those areas, plus many speed bumps slowing your down, made it seem crazy to see half a neighborhood lit-up with the actual speed limit as congested just from little ole me.

"Playing pac-man" suggests that not enough data was collected in these streets - but Waze felt it could generate trafficreports nevertheless? Maybe this is not what shirlig is looking for, but pls report it in detail.

[fvwazing]

I was driving at 131 km/h, and Waze said that the average speed was 58 km/h.

What about the wazer in front of you? May have caused it as well...

...then the jam would have disappeared after driving 1-2 km into the segment. Did it?

[fvwazing]

On a stretch of road the speedlimit was adjusted from 70kmh to 50kmh, some 6 months ago. Since then every wazer going over that stretch with 50kmh causes trafficjams - of 50kmh (yellow). Even though there has not been a single Wazer going at 70kmh over a period of 6 months - the maximum speed was never adjusted.

[gerben]

I see this a lot lately, often on the same roads, so it might be network related indeed,

[gerben]

This afternoon, I hit some medium traffic. The strange thing was, that two segments in front of me also turned yellow. AFAIK, there were no other wazers arround, and traffic was flowing freely at those segments (selected in the permalink).

https://world.waze.com/editor/?zoom=4&l ... ,161092588

[gettingthere]

I am not understanding the first post. 'Ghost' traffic jam meaning what?

False, traffic jam? Ie, you are not travelling with traffic (stopped at Drive Thru, Gas station, etc), and your Waze session creates a false jam on a nearby segment? Is this the information that is being requested?

Ghost traffic jam would be as AlanOfTheBerg describes, a jam that appears and there is no Wazer (including you) in the vicinity. No Wazer = Ghost.