Route recalculation, an imperfect science

Use your nav to take you to any destination in the UK...

it gives you the fastest route

When you get to your destination, use the nav to take you home... again using the fastest route.

There never the same!!!


Logic should say, its the route there in reverse, after all that was the quickest route to get you there :)


Mart ;)
 
That's a pretty good guess. Quite why it wouldn't re-route me to the next known shaping point which was about a mile away in the town and from there to the rest of the route, I am not sure. I have a nagging feeling that the modern devices - like the Nav V and its Garmin equivalent - like to have a few waypoints built into custom routes, as opposed to just lots of shaping points. With my A to B route there was only two waypoints, the departure hotel and the arrival hotel, separated only by my custom made route consisting entirely of shaping points.

The odd thing then is thst my two friends also made recalculations; sometimes their devices made them perfectly, sometimes they didn't.

It appears from what i can glean from the web that if a point (waypoint,via,shaping) is missed (not ridden through,bypassed, ignored) as you ride your route, and you then come to a point where you need to or are asked if you want to recalculate, say at a road closure or you stray off route, the sat nav will then take you back to the last missed point, and then re route you from there using its pre set preferences, you may have missed several points, what occurs then i do not know, it may go back to each one, until it has routed through them all, and then begin to take you to your destination, if you have not missed any points on your route, or you have actually told the satnav to skip the point or points, it should in theory take you to the next available point going forwards. as i say i dont know and can not test it due to not having the latest device.
With reference to to the detour functions,
If you are on a route and come across a road closure blockage or whatever. you can use the detour function tap 3 bars in the lower RH corner select Change route - Detour then select preferred option, this is for the 590 but may apply to other units.
Skipping a point in your route
If you pass a waypoint and the device did not announce it (no route directions given until you either go back to it or skip it), you can skip it by (in the map view) tap 3 bars in the lower RH corner select skip, it will then direct you to the next waypoint/shaping point. This prevents the device attempting to route you back to the missed point.

The txt below could be very helpfull for some as it will show changes to a route and also alow you to see what has altered and where, this is from another source.

Tracks (tracks are a representation of intended route that never alters)
Before you set off on your route It's worth laying a track for reference.
Track settings go to Apps - Tracks select track (that's been sent from Basecamp). (To Convert a route to a track in Basecamp on your PC right click on the route's name in the left hand listing and select "Create Track from (Selected) Route) tap wrench icon tap "Show on Map" tap "select colour" I use black.
What you'll see on the Map page when the route is activated is the magenta route path of your Trip with a black line in the middle that is the track (if your GPS is capable) so whenever the device re-calculates (auto or you click yes if prompted) you will see how and where it changes your route.
You will notice if the device re-calculates off the track, If you ignore this and stay on the track (black line), not on the Magenta route, there will be no route directions given until you re-enter the magenta route. Actually route directions are only given on the magenta regardless.

In Tracks - Wrench Icon You can alsouse the "Convert to Trip" option if all you have is a track. This is an excellent feature for those of us that travel on roads or trails that may not be on the map. Converting the Track will create a new Trip (route) of the same name in the Trip Planner that is usually a complete representation of the original Track. Now when I want to navigate the Track I go to the Trip Planner and select my "converted-track" and press GO.

I used the theme editor at the following address to modify the theme on the unit and double the width of the track. Makes it much easier to see. http://www.javawa.nl/zumocolors.html

As i have said this information is only what i have picked up, i can not prove any of it, and it may be all rubbish but those of you who have the newer devices could at least try and see if it is correct, and pass on your opinions.

This may go some way to explain why you are getting the weird route after recalculation,
 
I was interested to see that others have now commented on strange or unexpected routing when using the motorcycling profile. I have been experimenting with this. My car settings only avoid unpaved roads, my bike settings also avoid motorways. In all other respects all settings on the device are the same. I do not use Basecamp for route planning so all my routes are produced using Mapsource.

Using the car setting on my device routes appears to work as expected. Routes transferred to the device are displayed as planned. If I go off route the auto recalculate directs me back on the route to the next via point and the route remains otherwise unchanged. If I simply select a destination the device plots a route that does seem to be logical.

In the bike mode the device also copes well with the transferred route as long as there sufficient via points inserted. In this mode it appears more sensitive to this in that it will sometimes pick very minor roads for no obvious reason. It is as if it "sees" these roads, many of which are national speed limit roads, as being a better option than the B road which may well be blighted by 50 mph restrictions. In the same way if I select a destination in bike mode the device will often send me down narrow lanes and ignore the obvious main road option. As I said the only difference in the settings I have selected between the two modes is that in bike mode I had selected avoid motorways.

On my latest test runs using bike mode the device worked as expected on the way to my destination using a route made with multiple via points. The return journey was plotted (in Mapsource) by selecting the two waypoints-my starting point and home-and allowing Mapsource to create a route. I then dragged and dropped to create just enough via points to get the route I required but not as many as on the outward route. This route also transferred as intended. However, soon after setting off there was a short diversion which caused the device to recalculate. It did indeed recalculate a route to the next via point but that route ignored the B roads I had used on the outward journey and took me on a succession of lanes that meandered in the general direction of that via point. The result was my speeds were much lower and I had around 20 minutes added to my journey

Obviously there will be those who enjoy riding on narrow bumpy roads with gravel up the middle, I'm not one of them! Last time my device did this I ended up on something that most farmers would have been ashamed of, not only narrow but covered in gravel and potholes. The, thankfully, short route actually took more than three times as long to ride as a more direct route would have done despite being slightly shorter.

I should add that all these test runs were made using routes created using the latest Garmin maps and with my device switched to those maps rather than my preferred OSM ones.

It would appear, as I suggested in an earlier post, that something else is going on. Is there something in that bike mode setting that we can't see? Why does the device when set in bike mode have this tendency to pick tiny roads in preference to those that are faster in the real world? I would have said that it is ignoring the "fastest" setting and using "shortest" instead but it also throws in completely random and illogical additions to my route. The current situation means that the very useful facility of have two sets of settings which we can switch between is simply not viable. I would like to be able to use the bike setting to use fun routes and then, if required, switch to the car mode to just get me to my destination a quickly as possible. I can't do that because of the nonsense that the bike mode creates.

John
 
John just as a matter of interest what cradle are you using for the car and bike.
 
Re the post #24.
I was in Yorkshire last weekend in the car. My Zumo 390 does double duty.
Asked it to take me to an RSPB reserve about 20 miles away. Forgot it was in bike mode and got taken a very circuitous route via all sorts of single track scenic roads.
Changed it to car mode for the return and got taken straight back on A roads and dual carriageways. Much more direct and faster.
No other settings were changed.
There are elves involved, I tell you. Elves and sprites.
 
Maybe it depends what voice your using a mans voice or a womans voice and remember 2 women dont think the same so all sat navs will route different unless using the same voices :nenau
 
John just as a matter of interest what cradle are you using for the car and bike.

The ones that came with the 390. The bike mount is wired through an ignition live using the supplied lead. In my car I have hard wired the lead in from the back of cigarette lighter socket but keeping the lighter socket plug in the circuit. I opened up the plug, unsoldered the connections so I could feed the cable through the dash, re soldered the connections and then soldered supply cables to the power in parts of the plug. I now have a mount permanently fitted to an easily replaceable part of the centre console with the USB connection sprouting up out of the panel. No more trailing wires and the device is mounted where I can see it without being an obstruction in the windscreen. Occasionally I have used the 390 in my wife's car but we have a dedicated car device that is normally used in that car.

John
 
This has happened to me on my 660, taking me over roads where average speed was down to about 20mph on my fully laden 1150.

After a bit of faffing about I found that changing the 'vehicle' from bike to car improved things no end, it would seem that whoever programmed the thing assumed that bikes always want to travel via (very) tiny back lanes, this was in France.

I now always have my 660 set to 'Car'... though I nearly always use custom routes, but it is handy when encountering road closures.

Thanks for the tip have just spent about 10 min working out how you change the 590 from bike to car looking in the menus when you actually tap the bike icon at the top of the screen Hhhmm:confused:

Will try in car mode for a few trips see if this works better. Will also set basecamp for car too!!
 
I find it incredulous any GPS user, is surprised by the outcomes described in the original post.
Surely this is the experience we all have. Whats new?
 
Sat Nav can be the work of the devil

I use them, but mainly on scrolling mode (not doing a route)

I still much prefer a map in my Baglux map case to follow and a pair of eyes to read the road signs

+1 thumb
 
The txt below could be very helpfull for some as it will show changes to a route and also alow you to see what has altered and where, this is from another source.

Tracks (tracks are a representation of intended route that never alters)
Before you set off on your route It's worth laying a track for reference.
Track settings go to Apps - Tracks select track (that's been sent from Basecamp). (To Convert a route to a track in Basecamp on your PC right click on the route's name in the left hand listing and select "Create Track from (Selected) Route) tap wrench icon tap "Show on Map" tap "select colour" I use black.
What you'll see on the Map page when the route is activated is the magenta route path of your Trip with a black line in the middle that is the track (if your GPS is capable) so whenever the device re-calculates (auto or you click yes if prompted) you will see how and where it changes your route.
You will notice if the device re-calculates off the track, If you ignore this and stay on the track (black line), not on the Magenta route, there will be no route directions given until you re-enter the magenta route. Actually route directions are only given on the magenta regardless.

In Tracks - Wrench Icon You can alsouse the "Convert to Trip" option if all you have is a track. This is an excellent feature for those of us that travel on roads or trails that may not be on the map. Converting the Track will create a new Trip (route) of the same name in the Trip Planner that is usually a complete representation of the original Track. Now when I want to navigate the Track I go to the Trip Planner and select my "converted-track" and press GO.

I used the theme editor at the following address to modify the theme on the unit and double the width of the track. Makes it much easier to see. http://www.javawa.nl/zumocolors.html

I always create a track in basecamp as I build a route this gets sent together with the route when I completed it in basecamp.

So before I activate the route on the 590 I will go into Apps - Tracks - select track I want to display on the map - tap wrench icon tap "Show on Map" tap "select colour" black.
What this does is displays your intended route as a black line clearly visible down the centre of the route/road.

Then go to Apps - trip planner - activate the same route.
If the route is not recalculated by the transfer to the GPS the magenta route and track should stay together on the same route. If the GPS recalculates en-route it becomes easier/clearer to tell if you are no longer on your desired route.

If you are like me keen to stay on exactly the route created in Basecamp then this is a great tool and very quick to implement and display, when you zoom in and out of the map it shows up clearly.
Once I have completed the route I simply untick the show on map or delete it. It really only takes a few seconds to set up or remove.

I was caught out recently on our last trip in France started the route but as we were leaving Rennes one of our group needed petrol detoured to a station, as I hadn't added the fuel station to the trip once fuelled up I reset the route but as we weren't close to the start or on the route the 590 recalculated the route a different way (as it does). I picked this up straight away as we entered a dual carriageway looking at the GPS no track on the Magenta line. Easily resolved just zoomed out on the map and started heading in the direction to get me back to the track.
 
I know all about tracks, routes, plotting my own routes, transferring them to a GPS device, transferring them back again, routing preferences, the difference between car and motorbike modes, 'windy roads', using BaseCamp / Mapsource.

All that really interests me - and was the purpose of this thread - is why, when running a route A to B (lovingly and carefully created by me with simple shaping points between the two fixed way points A and B) the device - when requested - offered up a recalculated route to avoid a simple diversion in a town, that made no logical sense. A recalculated route which, had I been a numpty and blindly followed it, would have taken me miles out of my way, backwards onto and then off a motorway and then back into the same town; all before rejoining my route.

The only reason I requested the recalculation was just to see what happened when the device was confronted with an easy to navigate mile or so of easy diversion in a medium sized town. What I was offered up with by way of recalcution was so bizarre that it defied even my fervent imagination.

As nobody seems to know (though I suspect Leedude may well be the closest with his guess) I'll ask Garmin. I've saved the route I created and have the track I rode of the quickest way through the diversion in the town.

I'll ask Garmin why the device's recalculation of how to navigate the short diversion - and from there take me to my next shaping point (a relatively short distance away) - was so bizarre, involving leaving the town, riding away, joining and leaving a motorway, coming back into the town and, for all I know, repeating the process until the end of the world itself.

When and if I hear from Garmin, I'll let everyone know.

PS Other than this one oddity, the Nav V device and all the 2,500 or miles miles of created routes (all made on a Mac in BaseCamp *) around Germany and back into France has performed admirably.

* Which, if nothing else, puts a lie to the oft spouted belief that such a thing is impossible to do.
 
Interesting to hear of the differences and I'm keen to learn more. The more I use mine (590 LM) the easier it gets and the more impressive it is. We were away last week with no pre-planned routes and both of us using a 590 and a Nav 4. With the settings matched there were occasional differences but as we both had paired comms we could talk through the differences and it was never a problem. The use of comms also helped with overtakes and warning for gravel or diesel on the road. Tracking the coast and orientation to rivers etc helped with general routing and the occasional look at a Michelin route planner map certainly helped.
I do need to swap between track up or track north depending on whether I am checking the route when stationary or actually navigating.
 
I know all about tracks, routes, plotting my own routes, transferring them to a GPS device, transferring them back again, routing preferences, the difference between car and motorbike modes, ', using BaseCamp / Mapsource.

..............................

The only reason I requested the recalculation was just to see what happened when the device was confronted with an easy to navigate mile or so of easy diversion in a medium sized town. What I was offered up with by way of recalcution was so bizarre that it defied even my fervent imagination.


Given the second statement I think you might need to re consider the bit I have highlighted in bold!

The problem you describe sounds very much like the strange routing I and, it would appear, others have reported when using the motorcycle mode. There appears to be other factors used by the device in addition to any settings made by the user. The results remind me of the sort of nonsense that early versions of Basecamp produced until the user re set all the preferences and avoidances, I'm sure folk will remember the mess that Basecamp made of imported routes before we found the solution.

The thing is I don't use Basecamp so my device is not picking up settings from there. Given that fact we are pointed towards the device software. There must, I think, be hidden software settings telling the device to seek out funny little roads preferably with gravel down the middle because some nerd in Garmin HQ has decreed that that is what us bikers want. I wonder if Garmin will tell us if we ask? At the moment I think we are some way off knowing the difference between these modes.

John
 
Thanks for the replies everyone. Did you, John, ever contact Garmin / get a reply from them as to what you saw on the screen?

The roads the device proffered up in the recalculation were not small gravel tracks. They were large German roads including a motorway. I'll now leave it to Garmin to explain, if they will, what and hopefully why it happened; which is all that I want to know. Given that I rarely if ever use recalculation (preferring to get myself out of any trouble, I - or German roadworks - have created) and am otherwise perfectly happy with BaseCamp, the maps it offers, the device's interface with my Mac, the reading of the SD card (others may well be less so) and all the routes I create and as I don't play music, use the phone or have any voice prompts st all (which seem to trouble so many) I'll leave it at that. If Garmin ever tell me, I'll let everyone know.

For what it's worth, I asked the device to generate a route to take me to home in central London from the Chunnel; which it did perfectly. I purposely went off-route about 3/4 of a mile from hone, turning off the automated route's magenta line on the major A road, The Highway towards Tower Bridge and took instead the smaller Glamis Road, Wapping High Street alternative, running closer to the Thames. As I turned off into Glamis Road I pushed the 'deviation' button, which worked very well. There again, as it was running a device generated route, as opposed to one I had created with shaping points between two fixed waypoints A and B and was near enough on my doorstep, it maybe found it easier?
 
No, I have not contacted Garmin. My experience of them is that sending an Email is a waste of time, Calling them, which I have done on several occasions, has brought mixed results, I guess it depends on who answers. Some staff know what they are talking about others simply don't. One day I might try on this question but I think I would have to have a few examples to throw at them. Meanwhile I will avoid the motorcycle mode as it just brings grief. In car mode I am, like Wapping, happy with my device. For the same reasons I will continue with Mapsource and the use of OSM maps in preference to the Garmin ones.

John
 
I always create a track in basecamp as I build a route this gets sent together with the route when I completed it in basecamp.

So before I activate the route on the 590 I will go into Apps - Tracks - select track I want to display on the map - tap wrench icon tap "Show on Map" tap "select colour" black.
What this does is displays your intended route as a black line clearly visible down the centre of the route/road.

Then go to Apps - trip planner - activate the same route.
If the route is not recalculated by the transfer to the GPS the magenta route and track should stay together on the same route. If the GPS recalculates en-route it becomes easier/clearer to tell if you are no longer on your desired route.

If you are like me keen to stay on exactly the route created in Basecamp then this is a great tool and very quick to implement and display, when you zoom in and out of the map it shows up clearly.
Once I have completed the route I simply untick the show on map or delete it. It really only takes a few seconds to set up or remove.

Great tip, thanks.
 


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