Route Planning Anomaly

My "home" location is on a north/south road and it's set to my street address. 99% percent of the time, my position indicator is pointing north when I'm stationary and get a signal lock. Most of my planned trips head north so I hadn't noticed a problem until yesterday.

I was at home, stationary, and my indicator happened to be pointing south. I planned a trip that should take me northward on my street. Instead TomTom planned the route as if I wanted to go south. It basically took me in a giant circle about 1 mile out of the way in order to get where I was going.

I though I'd get smart and trick it into heading north immediately. So I told it to avoid that southern part of the route. The new route still took me 1/2 mile south before having me turn around to go north. Again wasting a full mile.

I understand why it's doing this. Since the indicator points south, it thinks I'm either driving south or already parked on the road and facing south. So it then takes the safest route or a route where I can safely turn around.

I don't understand why the indicator is either pointing north or south when it's on/near my road and I'm stationary. Does the TomTom have a "snap to road" built-in so you're always pointing in a direction of travel even when you're really parked?

I'm thinking I could "solve" this problem by setting my "home" location to the actual coordinates of my house which is 130 feet to the west of the road. Then I'm thinking the indicator will never "think" it's on the road already pointing in a particular direction of travel. It should then always take me 130 feet east and have me turn left or right... no matter which way the pointer started out.

Nope. I'm sitting at my desk 130 feet from my road. I set my "home" location to "my current position". I then browse maps and it shows the "home" icon in the proper place... I'm expecting to see my indicator arrow right on top of it (I have not moved an inch) and instead the arrow is sitting on top of the road 130 feet away. How can my home position be any different from my present position when I'm in the exact same location I used to set the home position? I suspect that this would confirm the presence of a "snap to road" function to always keep your indicator on track.

I'm posting this to confirm my suppositions and give others some possible insight into trip planning issues.

Just forget about it. Don't try to readjust the route, just keep driving, TomTom will reroute will split second.
My TomTom behaves like that all the time.

I guess this has something to do with gps lock signal strength. I think it somehow knows in which direction you are facing. I experienced the same thing last Saturday as I dropped-off a couple of friends to their house. I was facing the opposite direction of what I knew would be the fastest way to the autobahn. I did give it a try to follow TT's directions and it led me around the city first and it was around a 5 km trip.

lec510 said:

Just forget about it. Don't try to readjust the route, just keep driving, TomTom will reroute will split second.
My TomTom behaves like that all the time.

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Yes, I understand it will re-adjust the route as I drive. It's just nice to see the correct route/distance/ETA before I leave.

It would also be nice to only understand the device's limitations. Does it snap the arrow to the closest road as I suspect? If so, what is the resolution?

Thank-you.

zerimar said:

I think it somehow knows in which direction you are facing.

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I'm fairly certain this is impossible unless you are moving.

I tried the same thing recently; originally I set my home to the street address, but in reality my house is about 800 feet off the road. So while I was sitting in my driveway I set a new home position to the GPS coordinates.

Then the next time I chose the route to home option it did some calculating and stopped with an error message that it couldn't create a route to my destination. So I reset my home location back to the street address and everything started working fine again.

I haven't done any further testing, but for some reason it appears the software can't generate a route if the final destination isn't actually on a road. Regarding the anomaly you describe, I don't think I've actually seen this. But I agree, just start driving in the direction YOU want to go and the GPS will figure out what's happening very quickly.

I set my "home" location to my garage but instead of using readings off the TomTom, I manually set the coordinates that I obtained from Google Earth. I then walked back into my house which is not connected to the garage.

It took a few minutes but after the next reset or reboot, it correctly showed the home icon 150 feet off the road where my garage should be. It also correctly showed my current position just north of my garage which was inside my house.

But the next time I turned it on while inside the house, the current position automatically snapped 130 feet over to the center of the road.

I'm thinking this is caused by one or a combination of the following...

1. Resolution is too low so the unit just "snaps to road."
2. Unit is not very accurate when you're not actually moving.
3. Perhaps a lower signal strength when inside a building contributes to some inaccuracies.

Boyd said:

I tried the same thing recently; originally I set my home to the street address, but in reality my house is about 800 feet off the road. So while I was sitting in my driveway I set a new home position to the GPS coordinates.

Then the next time I chose the route to home option it did some calculating and stopped with an error message that it couldn't create a route to my destination. So I reset my home location back to the street address and everything started working fine again.

I haven't done any further testing, but for some reason it appears the software can't generate a route if the final destination isn't actually on a road.

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I think there must be some other reason for you getting this error.

I picked a point about 500 yards into a corn field nearby as my destination. It calculated a route right up to the nearest edge of the road as the official destination with checkered flag. It did not take me into the field and up to the point I chose but it did NOT give me any error either.

Also, when I have my official "home" set to the coordinates of my garage that are 150 feet off the road, my routes take me right up to the entrance of my driveway. Even though I'm asking it to take me to my "home" icon, it stops at the edge of the road and makes that the official destination. Again, no errors.

I have no complaint with that but it must be frustrating for people that live on unmapped roads or subdivisions.

Boyd said:

... the next time I chose the route to home option it did some calculating and stopped with an error message that it couldn't create a route to my destination.

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I remember getting this error last weekend... I changed and re-calculated the stored route too many times. I had to clear it out and start over... then it was fine.

Maybe set your home location 800 feet back and try to route again. It should take you right up to the entrance of your driveway.

sparky672 said:

Also, when I have my official "home" set to the coordinates of my garage that are 150 feet off the road, my routes take me right up to the entrance of my driveway. Even though I'm asking it to take me to my "home" icon, it stops at the edge of the road and makes that the official destination. Again, no errors.

I have no complaint with that but it must be frustrating for people that live on unmapped roads or subdivisions.

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It is.

My subdivision is about a year old, still being built, but the roads have been set for a year. The way Alabama works, the roads do not become part of the county/city/government until the last house is sold. Accordingly, I won't even have the streets verified for some time yet.

When I start out in the garge, the TT1 realizes I am in a field, so it shows the pointer there.

When I browse the map, it shows my house in the field.

When I route a trip to my house, it puts the checkered flag on the street at the subsivision entrance.

The corny thing to me is how did the TomTom ever figure out where the subdivision entrance is? My house location, if snapped to the nearest location on the street, would not be the subdivision entrance... so that seems odd to me, as if there is more data in there than I am allowed to use or something.

arrgh.

Something else I noticed that supports my whole "snap to road" theory.

While slowly turning into my driveway, which of course is off-road, the pointer starts to rotate in the new direction of travel, then it suddenly snaps back onto the road but facing 180 degrees from my original route. Then after I travel into my property a little bit, it snaps back off the road and correctly shows my direction of travel.