Segment Lengths

Moderator: Unholy

Re: Segment Lengths

Postby CBenson » Wed Mar 13, 2013 9:36 pm

kpouer wrote:If a segment is 20km long and there is some traffic jam on 3km, I think it will be hard to detect.

I'm not understanding. If you have a stoppage 1km into a 7km segment, waze can detect that and the segment should turn dark red or black. If the jam doesn't significantly affect the average speed because the segment is so long, then why is the information significant for routing decisions?
Regional Coordinator: Mid-Atlantic, US
Verizon, Nexus 6, Android 6.0.1, Waze 4.7.0.902
CBenson
EmeritusChamps
EmeritusChamps
 
Posts: 10330
Joined: Wed Nov 03, 2010 9:13 pm
Location: Crownsville, MD, US
Has thanked: 1055 times
Been thanked: 2353 times

Re: Segment Lengths

Postby kpouer » Wed Mar 13, 2013 9:56 pm

Because if you loose 10 minutes on 1km it is important, if you loose 10 minutes on 7 km it is not so important. If it is under the threshold to detect a traffic jam, waze will use the known average of the segment and ignore that you loose 10 minutes.
Area manager entre Paris et l'Auvergne
Coordinateur France
Country Manager Algérie http://www.facebook.com/WazeAlgerie & twitter: http://twitter.com/WazeAlgerie
Country Manager west Africa
kpouer
Coordinators
Coordinators
 
Posts: 7198
Joined: Sat Mar 13, 2010 9:47 pm
Location: France, Paris
Has thanked: 519 times
Been thanked: 2059 times

Re: Segment Lengths

Postby CBenson » Wed Mar 13, 2013 10:20 pm

When I lose 10 min on a 7 km segment that usually takes me 4 min to travel, waze marks the segment as jammed.

Even on a 20km segment with an average speed of 105 kph, a 10 min delay would almost be halving the average speed.
Regional Coordinator: Mid-Atlantic, US
Verizon, Nexus 6, Android 6.0.1, Waze 4.7.0.902
CBenson
EmeritusChamps
EmeritusChamps
 
Posts: 10330
Joined: Wed Nov 03, 2010 9:13 pm
Location: Crownsville, MD, US
Has thanked: 1055 times
Been thanked: 2353 times

Re: Segment Lengths

Postby kpouer » Wed Mar 13, 2013 10:32 pm

Maybe, and on very long segments, I don't expect a lot of traffic jam as they are not in urban area usually.
There is still my other problem on traffic data on very long segments if the geometry is changed (and also because I don't know what happens with erratic network connections.
Area manager entre Paris et l'Auvergne
Coordinateur France
Country Manager Algérie http://www.facebook.com/WazeAlgerie & twitter: http://twitter.com/WazeAlgerie
Country Manager west Africa
kpouer
Coordinators
Coordinators
 
Posts: 7198
Joined: Sat Mar 13, 2010 9:47 pm
Location: France, Paris
Has thanked: 519 times
Been thanked: 2059 times

Re: Segment Lengths

Postby jasonh300 » Wed Mar 13, 2013 10:56 pm

Actually, on a long segment, if cars are entering the segment, but not leaving the segment in the time it would normally take at average speed, the average would start to drop and approach 0 until the cars that have entered the segment have moved on to the next segment.
jasonh300
EmeritusChamps
EmeritusChamps
 
Posts: 7568
Joined: Fri Oct 28, 2011 4:26 pm
Location: New Orleans, LA, USA
Has thanked: 407 times
Been thanked: 976 times

Re: Segment Lengths

Postby kpouer » Wed Mar 13, 2013 11:11 pm

But if the segment is very long it can take one or two hours (when the segment is 100km long), and I'm not sure how waze will do if the next intersection is at a place where there is no network ? It will never get the speed of the segment ?
Area manager entre Paris et l'Auvergne
Coordinateur France
Country Manager Algérie http://www.facebook.com/WazeAlgerie & twitter: http://twitter.com/WazeAlgerie
Country Manager west Africa
kpouer
Coordinators
Coordinators
 
Posts: 7198
Joined: Sat Mar 13, 2010 9:47 pm
Location: France, Paris
Has thanked: 519 times
Been thanked: 2059 times

Re: Segment Lengths

Postby jasonh300 » Wed Mar 13, 2013 11:18 pm

kpouer wrote:But if the segment is very long it can take one or two hours (when the segment is 100km long), and I'm not sure how waze will do if the next intersection is at a place where there is no network ? It will never get the speed of the segment ?


In the real world, how many segment are 100 km long without any kind of exit or junction or change in city name? What good is traffic jam reporting going to do if you break it up into short segments if the jam is at the very end of that 100 km segment--you'd have to scroll all the way across the map to see it. On those roads that actually are 100 km without a junction, are there really going to be any traffic jams? In a situation like that, even if you could see the jam, would there even be an alternate route? I'm thinking the remote Australian outback or something where a highway sees a dozen cars a day, and there's no other route.

I just don't see this sort of thing coming into play in very many places.
jasonh300
EmeritusChamps
EmeritusChamps
 
Posts: 7568
Joined: Fri Oct 28, 2011 4:26 pm
Location: New Orleans, LA, USA
Has thanked: 407 times
Been thanked: 976 times

Re: Segment Lengths

Postby ncc1701v » Thu Mar 14, 2013 3:25 am

kpouer wrote:One problem with long segments is traffic jam detection.
If a segment is 20km long and there is some traffic jam on 3km, I think it will be hard to detect, and if not detected waze will use the known average speed of the segment and not the current speed due to the traffic, don't you think?

We've been here before :-). The goal is getting to your destination quickly. For a given segment, you cannot get on or off, so what matters is the average speed for the whole thing -- the speeds on different parts of the segment don't make any difference in navigation. Personally I prefer to have clean roads and few junctions.

kpouer wrote:The other problem is to know what happens to the average speeds that waze knows if the segment geometry is changed, the segment splitted ...

It's better to retain existing segments if you can, no?
... and the "v" is for Volvo.
ncc1701v
 
Posts: 547
Joined: Thu Jun 07, 2012 6:08 pm
Location: Ithaca, NY USA
Has thanked: 49 times
Been thanked: 45 times

Re: Segment Lengths

Postby bgodette » Thu Mar 14, 2013 4:17 am

kpouer wrote:Maybe, and on very long segments, I don't expect a lot of traffic jam as they are not in urban area usually.
There is still my other problem on traffic data on very long segments if the geometry is changed (and also because I don't know what happens with erratic network connections.
WME's backend takes care of recomputing time-slot transit times for any modified or split segments. This is likely why saves involving node removal can take a while.

Incidentally this is something that Cartouche did NOT do. Changes to segment length did not modify transit time, so if you lengthened you'd make routing think that segment was faster, shorten and it looks slower.
bgodette
Waze Global Champs
Waze Global Champs
 
Posts: 3441
Joined: Wed Jul 06, 2011 8:19 pm
Location: Denver, CO
Has thanked: 122 times
Been thanked: 542 times

Re: Segment Lengths

Postby kpouer » Fri Mar 15, 2013 11:32 pm

ncc1701v wrote:
kpouer wrote:The other problem is to know what happens to the average speeds that waze knows if the segment geometry is changed, the segment splitted ...

It's better to retain existing segments if you can, no?


Right but I'm also mapping in Africa, there is no basemap. So I'm drawing major roads first. For example I created the beginning of Trans-sahara highway, already 2400km. Usually it's very straight lines in the desert. Then I may add some crossing roads if necessary so I have to split sometimes, or move the road because in some places I had to assume it's position without GPS dot and without satellite view.


@bgodette, thanks for your answer, so I can split or merge segments without problems. But do you have an option on very long segments ? If the segment is too long like 50km, I'm affraid that waze may not be able to get any valid time as too many problems can occur (like having no network at the beginning of the road or the end, or things like that).
Area manager entre Paris et l'Auvergne
Coordinateur France
Country Manager Algérie http://www.facebook.com/WazeAlgerie & twitter: http://twitter.com/WazeAlgerie
Country Manager west Africa
kpouer
Coordinators
Coordinators
 
Posts: 7198
Joined: Sat Mar 13, 2010 9:47 pm
Location: France, Paris
Has thanked: 519 times
Been thanked: 2059 times

PreviousNext

Return to Wiki Updates and Discussion

Who is online

Users browsing this forum: No registered users