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hucker
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Joined: Oct 30, 2005
Posts: 97
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 Posted: Sun Oct 30, 2005 9:25 pm Post subject: Return route is DIFFERENT??? |
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I took a drive from Clackmannan to Strathyre today. I used the i3 to give me directions, and it got me there quicker than usual (I normally go along what I thought was the quickest route (I had either looked on a map the first time I went 2 years ago or used the AA website, I can't remember which)). Plus it was a more interesting route. I think it must deliberately go for higher speed roads (which makes it avoid built up areas, so I ended up going along nice country roads, and a section of motorway - which I thought would be out of my way by looking at the map, but I did in fact get there quicker!)
ANYWAY! The point I was making was..... I pressed "go home" when I was ready to return, and it told me to go a different way! Why? There are no one way roads here. Surely whatever is quickest one way is also quickest the other way - unless it's being REALLY clever and accounting for traffic levels at different times of day and different directions?!? |
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lbendlin
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Joined: 02/11/2002 22:41:59
Posts: 11878
Location: Massachusetts, USA
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| Posted: Sun Oct 30, 2005 10:25 pm Post subject: Re: Return route is DIFFERENT??? |
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| hucker wrote: | | Surely whatever is quickest one way is also quickest the other way |
Why should that be? Route calculation is based on penalties. A right turn has a much higher penalty than a left turn (assuming you drive in the UK) and this can already be sufficient to let the system decide to go straight instead of turning right etc.
"Return" journeys are an artificial contruct. The system always calculates from A to B, without knowing that it just calculated from B to A.
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Last edited by lbendlin on Sun Oct 30, 2005 10:36 pm; edited 1 time in total |
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hucker
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| Posted: Sun Oct 30, 2005 10:34 pm Post subject: |
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| I hadn't realised it took right turns into account. I guess my journey is almost identical times both routes, so the odd right turn could make all the difference. |
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Trajet
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Joined: Oct 04, 2005
Posts: 160
Location: Highlands of Scotland
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| Posted: Mon Oct 31, 2005 8:09 pm Post subject: |
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| I reckon it also takes traffic light into account. It will always try to put me up Nairn Hight Street which has no traffic lights in preferance to the A96 which has three sets. A96 is quicker as there is less congestion. :x |
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hucker
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| Posted: Mon Oct 31, 2005 9:08 pm Post subject: |
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| Trajet wrote: | | I reckon it also takes traffic light into account. It will always try to put me up Nairn Hight Street which has no traffic lights in preferance to the A96 which has three sets. A96 is quicker as there is less congestion. :x |
What are the speed limits on each? I assume it takes those as the road speed and ignores congestion?
| Trajet wrote: | | i3 in the Highlands of Scotland. If your going to get lost - this is the place to do it. |
Tis why I got a GPS in the first place - for touring the Highlands. I live down in the built up part between Glasgow and Edinburgh :-( |
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lbendlin
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Location: Massachusetts, USA
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| Posted: Mon Oct 31, 2005 10:31 pm Post subject: |
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| Trajet wrote: | | I reckon it also takes traffic light into account |
Neither NavTEQ nor TeleAtlas have that information yet. But I would think that this will be the next level for street navigation - route calculation that takes traffic patterns into account - including the potential of hitting a "red wave" on the lights.
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hucker
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| Posted: Mon Oct 31, 2005 10:40 pm Post subject: |
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| lbendlin wrote: | | Trajet wrote: | | I reckon it also takes traffic light into account |
Neither NavTEQ nor TeleAtlas have that information yet. But I would think that this will be the next level for street navigation - route calculation that takes traffic patterns into account - including the potential of hitting a "red wave" on the lights. |
I've found I don't hit red waves. They only exist if you drive slowly. If you go fast and run the lights when they've just changed, you don't get so stuck!
BTW - can't they time them so waves don't exist? My uncle always told me they made waves on purpose, but I think he was having me on :-) |
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Tim Buxton
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Joined: 14/09/2002 20:56:18
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Location: Surrey, United Kingdom
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| Posted: Mon Oct 31, 2005 10:46 pm Post subject: |
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| hucker wrote: | | BTW - can't they time them so waves don't exist? My uncle always told me they made waves on purpose, but I think he was having me on :-) |
In France they have signs which say that if you obey the speed limit then you will get all green lights after the first one; if you go too fast, you'll hit reds. Most folk appear to obey the speed limits where I've seen it in operation.
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hucker
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| Posted: Tue Nov 01, 2005 12:07 am Post subject: |
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| Tim Buxton wrote: | | In France they have signs which say that if you obey the speed limit then you will get all green lights after the first one; if you go too fast, you'll hit reds. Most folk appear to obey the speed limits where I've seen it in operation. |
I've driven right round France twice and never seen those (although I may have missed them as I don't know much French!). I did notice that most French drivers speed. The UK is far too tame. And there are very few speedtraps. Just don't get nicked with a radar detector - 750 euro fine and confiscated detector! At least if it doubles as a navigator I have an excuse! |
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MaFt
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Joined: Aug 31, 2005
Posts: 15142
Location: Bradford, West Yorkshire
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| Posted: Wed Nov 02, 2005 6:20 pm Post subject: |
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| Tim Buxton wrote: |
In France they have signs which say that if you obey the speed limit then you will get all green lights after the first one; if you go too fast, you'll hit reds. Most folk appear to obey the speed limits where I've seen it in operation. |
there's a road in manchester (can't remember which one but there are lots of curry houses and trafic lights!) that if you stick to the speed limit you will only hit one red light out of the 7 or so sets of lights. pretty funky eh?!
similar to the roundabout at the bottom of the m606 - once you're on it you stick to the speed limit and all the lights are green - it makes me laugh when people shoot by me at 40/50 and keep having to stop but me toddling along at 30 i keep up with them without wearing out my brakes  |
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dougconran
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Joined: Oct 07, 2004
Posts: 175
Location: Bury St Edmunds, Suffolk
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| Posted: Wed Nov 02, 2005 6:58 pm Post subject: |
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| Tim Buxton wrote: | | hucker wrote: | | BTW - can't they time them so waves don't exist? My uncle always told me they made waves on purpose, but I think he was having me on :-) |
In France they have signs which say that if you obey the speed limit then you will get all green lights after the first one; if you go too fast, you'll hit reds. Most folk appear to obey the speed limits where I've seen it in operation. |
Same in Germany. They have big signs on gantries above the roads (or, at least, they did a number of years back, maybe vandels have removed them by now 8O ) |
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hucker
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| Posted: Wed Nov 02, 2005 8:38 pm Post subject: |
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| MaFt wrote: | there's a road in manchester (can't remember which one but there are lots of curry houses and trafic lights!) that if you stick to the speed limit you will only hit one red light out of the 7 or so sets of lights. pretty funky eh?!
similar to the roundabout at the bottom of the m606 - once you're on it you stick to the speed limit and all the lights are green - it makes me laugh when people shoot by me at 40/50 and keep having to stop but me toddling along at 30 i keep up with them without wearing out my brakes |
They're not doing it right, you have to run a red light. You'd probably fool the system then and get the rest green! |
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