Inconsistent routing

[sgoldste01]

OK, so I'm mainly using my TomTom One 3rd Edition, which I received for Christmas, to drive around on roads near where I live and am familiar with. I do this mainly as a way of practicing and getting used to the TT's behavior, so that when I really need to get someplace new, I'll be comfortable with the device.

One thing that I do almost every day is drive from work to home, and almost every day the TT provides the same route. But yesterday it decided to take me on a hair-brained route that added 10 minutes to the trip. Now I know that I could have ignored its directions, and it would have re-routed me. But that's not the point.

Had I been driving someplace that I was unfamiliar with, I would have blindly followed its directions and taken the longer route (in fact, I did take the longer route because I was curious to see what it was up to).

So I have two questions for the forum:

1: Why would any GPS take me on a different route from one day to the next? If the maps don't change and the departure point doesn't change and the destination doesn't change, then why would the route change? I would expect it to plot the exact same route every day. WTF? Is it getting bored or something?

2: Has anyone else experienced this behavior on their TomToms?

 

[Joewee]

I have done the same thing with my TomTom, as far as driving on
familiar roads, to get comfortable with it. I have found that it usually
gives you the fastest route and have even found some new routes
I wasn't even aware of, that got me to familiar destinations faster.
However, no GPS on the market is falliable at this point and sometimes
they do make mistakes. Ultimately, though, they do get you do your
destination. One suggestion would be to make sure you update your
GPS coordinates online regularly. Perhaps you had some slight GPS fade
and it had you at different coordinates.

 

[sgoldste01]

I have done the same thing with my TomTom, as far as driving on
familiar roads, to get comfortable with it. I have found that it usually
gives you the fastest route and have even found some new routes
I wasn't even aware of, that got me to familiar destinations faster.
However, no GPS on the market is falliable at this point and sometimes
they do make mistakes. Ultimately, though, they do get you do your
destination. One suggestion would be to make sure you update your
GPS coordinates online regularly. Perhaps you had some slight GPS fade
and it had you at different coordinates.

I know that no routing engine is perfect; I can live with that. What bothers me is inconsistency. If I'm starting from the same place and ending at the same place, I expect the routing engine to tell me to go the same way every time. I lose confidence when the GPS tells me to go one way one day, and a different way the next day. Why would it plot a different route?

As for GPS fade, I always show solid satellite reception, so I don't think that's the problem.

 

[bwhite]

I know that no routing engine is perfect; I can live with that. What bothers me is inconsistency. If I'm starting from the same place and ending at the same place, I expect the routing engine to tell me to go the same way every time. I lose confidence when the GPS tells me to go one way one day, and a different way the next day. Why would it plot a different route?

As for GPS fade, I always show solid satellite reception, so I don't think that's the problem.

I'm not familiar with your unit, but, if it has the functionality, did you use the traffic feature? If so the thing may have been routing you around some sort of incident. I've been reading about various models where firmware updates have triggered routing oddities, if you had it plugged into the internet for any sort of updates it may have pulled down new firmware.

 

[sgoldste01]

I'm not familiar with your unit, but, if it has the functionality, did you use the traffic feature? If so the thing may have been routing you around some sort of incident. I've been reading about various models where firmware updates have triggered routing oddities, if you had it plugged into the internet for any sort of updates it may have pulled down new firmware.

The One 3rd Edition can receive traffic info via an optional add-on traffic receiver, which I don't have. So that's not the answer.

Thanks for the suggestion, though.

 

[drledger]

Not that I have the definitive answer but a supposition. TT uses a set of algorithms and their famous secret sauce formula to calculate recommendations. In a knowledge test with TT I usually win in local and route specific tests but the gps is engineered to get you from A to B in as reasonable route as possible and it did get me to my destination. The variance from day to day can be the difference in updates for satellites, the hd search engine simply missing a road............ or TT is playing with our minds .
I travel a lot in rural areas. TT's recommendations are not the best and would have me traveling very narrow and undeveloped roads. It will get me where I am going. I know better routes that may be a bit longer but I will make the difference in speed. I imagine we will see in the future a unit that will take into consideration our personal preferences and remember those for routing preferences and apply some of the much heralded "fuzzy logic" Voice recognition is certainly a step in that direction and we could simply tell the unit to take us "VIA THE PARKWAY" and to always use that route unless blocked.
GPS's are getting better but there is room for improvement.

 

[SShadow]

I've noticed this too... In fact, my TT will take me along a 50km/h stretch of road for 1/2 of my trip and then onto a high way to continue - when not far from my house there is an entrance to that same highway, that has a speedlimit of 110km/h (and yes, the TT knows it's a highway). The difference, at least in TTs route calc is 1km (the highway being the "longer" trip) but it is definitely NOT the fastest route to take - safety or no safety - as there are two sets of stop lights and slower speedlimit.
And of course, if I choose to route around the 50km/h road, I can't get home because the entrance to my subdivision is from that road. So I have to ignore it's advice and allow it to re-route after I pass the exit/get on the highway (depending on whether I am going home/back to work.)

 

[bwhite]

DR,
I think (and hope) you are right about building in User Pref fuzzy logic.
The factory Alpine in our Honda has a Best Route setting and it actually does that, I haven't spent much time trying to figure out it's criteria, I think maximizing the use of decent roads and minimizing smaller roads except for immediately surrounding the departure and end points.

 

[SoCalWizard]

I know, there must some logic behind it all, but how does it choose the fastest route? I used my new TT920 to come home the other day, and the route that it calculated was to pass my normal exit on the freeway and go to the next one down, whereby it then backtracked to my house. If I did get off at my normal exit, it would then re-calculate and indeed direct me home, also calculating a savings of 5 minutes on my trip. So how is it faster going the longer route?

I asked this before on another thread, it should have been in this thread. I just wanted to post my two cents also. TT's have a mind of their own, but at least it will get me home.

 

[F22]

I asked this before on another thread, it should have been in this thread. I just wanted to post my two cents also. TT's have a mind of their own, but at least it will get me home.

(well, besides making SoCal happy that someone replied!)

I am hoping that when I visit my sister in LA in the summer that the 920 does not take too many ODD routes. One of the reasons I purchased this item was a trip to LA after hiking around the Sierra later in the summer (and Costco's discount when I purchased it). So, I'm really hoping the Tomtom does not "drive" me crazy trying to negotiate around LA when I'm on my own.

 

[SoCalWizard]

Thanks, now I feel appreciated.
You know, I got to thinking about why maybe it's showing a longer route as the fastest. Is it possible that it has the wrong posted speed limit for the streets? How do you check?

 

[wbwjr]

Just think of all the new places you can discover by taking a new route!

(just kidding of course, I know it's frustrating)

 

[martinp13]

The One 3rd Edition can receive traffic info via an optional add-on traffic receiver, which I don't have. So that's not the answer.

Thanks for the suggestion, though.

As others have said, TomTom uses speed limits and probably time of day in brewing their secret routing sauce. Who knows what they use? I don't think 10 minutes is that big of a deal. If you had caught lights differently, it might have been closer. "Fastest" is very subjective when you're predicting.

 

[mrjig]

Who cares?

This issue seems to be of marginal merit.
I'm sure that if you are actually concerned you can figure it out.
dick

 

[sgoldste01]

This issue seems to be of marginal merit.
I'm sure that if you are actually concerned you can figure it out.
dick

Thanks for your informative response.

The next time, save yourself some calories and don't bother typing anything at all.

 

[dhn]

Thanks for your informative response.

The next time, save yourself some calories and don't bother typing anything at all.

Fortunately, there aren't too many like him hanging around here.

 

[SShadow]

Darn good thing too...

Another thing I have noticed is that sometimes it doesn't change the route at all, between fastest and shortest. *shrug*
I do wish, however, that the prompt when chosing the shortest would go away and never come back - you know the "We've done testing and you'll waste gas and be less safe if you take the shortest route" message. I understand - I don't need to see it every time I choose the shortest route.

 

[jzerocsk]

I haven't seen it give me different routes to and from the same locations at different times, but I have noticed that if I start at my parents house and set a route to go home it takes me along highway A and tells me to exit onto highway B. If I stop for gas along A, it will redirect me to exit onto highway C from highway A. Why would it suddenly appear faster to take one exit over the other?

In any case, I have come to the conclusion that GPS simply isn't that great if you sort of know where you're going. I don't think it will ever be possible for a GPS system to figure out the true fastest route all of the time.

As I tell prospective purchasers, the arrow always points to your destination. If you think you know a better way, feel free to try it feeling secure in the knowledge that even if you are dead wrong, you can always just follow the arrow to your destination. It might not be the best way to go, but you will get there.

Corollary to that - always reality-check your destination on Google Maps or something similar before you set out

 

[SoCalWizard]

...If I stop for gas along A, it will redirect me to exit onto highway C from highway A. Why would it suddenly appear faster to take one exit over the other?
...

That's what it does for me also. If I clear route or stop for gas along the freeway a few exits before my "normal" exit, then it would use the shorter/faster route. Any other time it would take me out further and then backtrack back to my house, adding about ten miles and 5 minutes to the trip.

 

[sgoldste01]

More info about inconsistent routing

OK, so here's what happened this morning:

I was at home and I told the TT to navigate me to work. I could tell by looking at the line drawn on the Route Preview screen that it was about to take me on a bad route to work. This **is not** the route the TT normally plots for me. So I cleared the route and again told it to navigate me to work. Again, it selected the bad route.

So I did a reset on the TT by pushing the paperclip button on the bottom of the unit. After it rebooted, I told it to navigate me to work. This time, it plotted the correct route.

Hmmm....