Segment Lengths

Moderator: Unholy

Segment Lengths

Postby kentsmith9 » Tue Mar 12, 2013 3:28 am

In a recent thread I was inspired to collect all the info we have on segment lengths and create a template or whole wiki page on it.

I believe we want to note the following and I would appreciate any other ideas:

* Max length allowed by editor from both initial creation and when connecting segments by removing nodes. (I believe we have seen this in the 10km range; I will do some tests unless someone already has.)
* Max recommended length - Explaining pros and cons of longer or shorter lengths on routing, visual traffic indicators, etc.
* Limit on stretching the length of a short road too far in one edit. Also if it is better to stretch it or draw a new road to preserve the traffic data on a segment.
* Min length
* The affect (if any) from connecting nodes (2 segments) on routing penalties, server load (back-end database management), editor complexity, turn restriction errors, etc. Also cover if it is any different for junctions (3+ segments).
kentsmith9
Waze Global Champs
Waze Global Champs
 
Posts: 5525
Joined: Mon Apr 23, 2012 3:33 pm
Location: SF/SJ Bay Area of Northern California
Has thanked: 1469 times
Been thanked: 1672 times

Re: Segment Lengths

Postby kentsmith9 » Thu Oct 23, 2014 3:07 pm

And I just saw this post from Alan discussing the junctions with RR crossings [underline added by me].
AlanOfTheBerg wrote:Junctions only impact routing until segment speed data is captured, then the junction "penalty" goes away. Waze doesn't need to have a project to identify RR crossings, because with a junction, the Waze speed capture does the rest automatically. Long delays at that junction will be collected and aggregated by the 10min/30min timeslice with all other stop light and stop sign data.
kentsmith9
Waze Global Champs
Waze Global Champs
 
Posts: 5525
Joined: Mon Apr 23, 2012 3:33 pm
Location: SF/SJ Bay Area of Northern California
Has thanked: 1469 times
Been thanked: 1672 times

Re: Segment Lengths

Postby kentsmith9 » Thu Oct 23, 2014 2:49 pm

bgodette wrote:
kentsmith9 wrote:The net result for routing is no different though. The routing engine will still account for the time change over the entire length of the segment the same as it would for ten 5km segments with the stoppage at the same point.
Routes with fewer segments are preferred by routing over a route with more segments even if the route with more segments seems to save some unspecified amount of time. Some percentage of the secondary route being a faster route is caused by this.

I thought we recently discussed this (over the last year and in Vegas) and confirmed that the junction itself only added time when the segments were without traffic data. Then once it had traffic data there was no time added for the junction if data existed.

The logic for adding time because of a junction would be ludicrous if you considered a major roadway through a city like El Camino Real through the SF Peninsula with hundreds of parking lot connections. In the real world, each junction to the parking lot has no affect on the straight through traffic beyond the measured average time to cross that entire segment. Waze repeatedly tells us they want to map everything eventually. They would not have such routing logic if that was the intent.
kentsmith9
Waze Global Champs
Waze Global Champs
 
Posts: 5525
Joined: Mon Apr 23, 2012 3:33 pm
Location: SF/SJ Bay Area of Northern California
Has thanked: 1469 times
Been thanked: 1672 times

Re: Segment Lengths

Postby kpouer » Wed Oct 22, 2014 10:17 pm

@bgodette, that's good news. During Barcelona meetup we were told that they were able to detect traffic on a sub-segment but not highlight a sub-segment yet. If they can now it's a good evolution, maybe we should ask if it is available on all servers.
kpouer
Coordinators
Coordinators
 
Posts: 6233
Joined: Sat Mar 13, 2010 9:47 pm
Location: France, Paris
Has thanked: 379 times
Been thanked: 1264 times

Re: Segment Lengths

Postby bgodette » Wed Oct 22, 2014 3:11 pm

kentsmith9 wrote:The net result for routing is no different though. The routing engine will still account for the time change over the entire length of the segment the same as it would for ten 5km segments with the stoppage at the same point.
Routes with fewer segments are preferred by routing over a route with more segments even if the route with more segments seems to save some unspecified amount of time. Some percentage of the secondary route being a faster route is caused by this.

kentsmith9 wrote:However, the net result for the visual will be different. The 50km segment will possibly never show slow traffic when you plot the route and look at the initial traffic. Only later will you run into the stopped traffic. With short segments, Waze can warn the driver of a slowdown of traffic because the segments are shorter and will be detected as different from their average.
FYI we've seen occasional peeks at traffic highlighting in the app showing sub-segment highlighting. Using highlighting as a thin justification for segment splitting is likely to be eliminated "soon".
bgodette
Waze Global Champs
Waze Global Champs
 
Posts: 3420
Joined: Wed Jul 06, 2011 8:19 pm
Location: Denver, CO
Has thanked: 110 times
Been thanked: 511 times

Re: Segment Lengths

Postby kentsmith9 » Wed Oct 22, 2014 6:37 am

The other reason we proposed shorter segment lengths was to better indicate where traffic slowdowns were on a long segment. If you are 50km long and at the end of that segment there is a stoppage, you won't see it because the average of 500m at 0 kph will not impact the 50km segment with 80kph average.

The net result for routing is no different though. The routing engine will still account for the time change over the entire length of the segment the same as it would for ten 5km segments with the stoppage at the same point. Since there are no turns off that road for the 50km, its not like you could get around the slowdown.

However, the net result for the visual will be different. The 50km segment will possibly never show slow traffic when you plot the route and look at the initial traffic. Only later will you run into the stopped traffic. With short segments, Waze can warn the driver of a slowdown of traffic because the segments are shorter and will be detected as different from their average.
kentsmith9
Waze Global Champs
Waze Global Champs
 
Posts: 5525
Joined: Mon Apr 23, 2012 3:33 pm
Location: SF/SJ Bay Area of Northern California
Has thanked: 1469 times
Been thanked: 1672 times

Re: Segment Lengths

Postby doctorkb » Tue Oct 21, 2014 4:16 am

banished wrote:Although I have a good system, it starts to drag if the segment length is over 70km. I don't know if that's my system or the WME, but you may wish to run your own tests in out-of-the way areas so we can arrive at a number that works for everyone.

Segment length was initially a railroad segment discussion. There aren't too many navigable segments that would reach that length (70km), but there may be a few in the Western US/Canada.


I've driven a lot of the highways around Western Canada and can tell you that, at very least, there is a forest service road that should be junctioned into a highway AT LEAST every 50 km.

I don't think 50km is unreasonable to specify as a maximum length.
doctorkb
Coordinators
Coordinators
 
Posts: 4055
Joined: Wed Nov 04, 2009 9:17 am
Location: Edmonton, Alberta, Canada
Has thanked: 621 times
Been thanked: 1605 times

Re: Segment Lengths

Postby doctorkb » Tue Oct 21, 2014 4:14 am

jasonh300 wrote:So refresh my poor memory of the metric system. 100 km is 100,000 meters, right?


Yes. Makes sense, right? Kilo for thousand, + meter equals one thousand meters is one 1 km. :)
doctorkb
Coordinators
Coordinators
 
Posts: 4055
Joined: Wed Nov 04, 2009 9:17 am
Location: Edmonton, Alberta, Canada
Has thanked: 621 times
Been thanked: 1605 times

Re: Segment Lengths

Postby jasonh300 » Tue Oct 21, 2014 3:35 am

banished wrote:Segment length follow up: I received an answer from Waze: It's up to 100km. For our purposes that is not effective until we agree to change it in the wiki.

Although I have a good system, it starts to drag if the segment length is over 70km. I don't know if that's my system or the WME, but you may wish to run your own tests in out-of-the way areas so we can arrive at a number that works for everyone.

Segment length was initially a railroad segment discussion. There aren't too many navigable segments that would reach that length (70km), but there may be a few in the Western US/Canada.

I'll open the bidding at 50km.


So refresh my poor memory of the metric system. 100 km is 100,000 meters, right?
jasonh300
 
Posts: 7568
Joined: Fri Oct 28, 2011 4:26 pm
Location: New Orleans, LA, USA
Has thanked: 408 times
Been thanked: 985 times

Re: Segment Lengths

Postby banished » Tue Oct 21, 2014 1:25 am

Segment length follow up: I received an answer from Waze: It's up to 100km. For our purposes that is not effective until we agree to change it in the wiki.

Although I have a good system, it starts to drag if the segment length is over 70km. I don't know if that's my system or the WME, but you may wish to run your own tests in out-of-the way areas so we can arrive at a number that works for everyone.

Segment length was initially a railroad segment discussion. There aren't too many navigable segments that would reach that length (70km), but there may be a few in the Western US/Canada.

I'll open the bidding at 50km.
banished
Waze Global Champs
Waze Global Champs
 
Posts: 783
Joined: Mon Sep 28, 2009 11:03 am
Has thanked: 229 times
Been thanked: 170 times

Next

Return to Wiki Updates and Discussion

Who is online

Users browsing this forum: No registered users