TomTom Weirdness on the approach to the Severn Bridge (M4)

[jweaver]

Indeed.. It is very strange.

What I have found is that if I am in the inside (slow) lane, it seems fine (although I have still seen my position shown on the wrong carrageway)..

However, if I am in the outside lane, or change lanes as I am going around the left hand bend (as if I was effectivly going straight on), then I end up in the field.

I know that there is little wrong with my GPS as comparing the position against my Garmin GPS 3, it shows the same position within .000001 of a degree.

It is very odd and I wish I could work out EXACTLY why its doing this.

Next time I go over, I am going to keep an eye on the amount of sats that I am seeing...

Jon

[MrT]

Mine does this on the A11 between Snetterton and Norwich, every time. However if I log the GPS and import it into Memory Map, it shows me following the A11 perfectly. Play back the GPS log in TomTom and it goes off road again. Must be in the map or interpretation of the GPS by TomTom.

[icsys]

Have you considered the possibility of a map locking error?
Not sure what TomTom call this feature which snaps your position to the road you are travelling on to avoid you wandering off due to GPS accuracy (5m<).
If you have ever tried using topo maps whilst driving that doesn't have such a feature you will know what mean.

If this snap-to-road feature has an error at any given point you will see your position veer off the map or in severe cases jump to a nearby or parallel road and always at the same location.
_________________
Ian.
iPAQ 2210 | Navman 4100 BT Receiver
Navman iCN 635
TomTom GO
Anquet OS mapping

[mpewsey]

Out of interest I've had the same kind of problem on the A370 (near Cleeve I think!) and the A38 near Bristol Airport.

As these roads are at either end of the runway I've always just assumed it was something at the airport interfering with the GPS signal.

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