Navman F20 + T1 re-routing algorithm Versus TomTom Traffic

[oolaa]

Having abandoned a TomTom Navigator 6 + GPRS traffic subscription due to (in my opinion) excessive data charges for a Navman F20 with Traffic module I have to say I'm disappointed with the Navman's method of automatic rerouting.

I can't speak for the TomTom TMC addon but the GPRS TomTom traffic appeared to behave as follows.

1) Traffic reported on planned route.
2) Alternatives calculated in the background
3) If alternative is quicker than Original route + delays then new route taken, If alternative is slower than original route + delays don't re-route.

I know that no system is magic but this seemed to work very well. The only downside to the TomTom approach is that once auto rerouted you are given no option to ignore the advice.

Now the Navman F20 seems to follow a less "hand's free" approach.

When in "warn only" mode it is in some ways more flexible in what it displays than Tom Tom ,as you can view both incidents on route & near your current location.

However every delay you wish to avoid requires 2 or more screen taps to avoid. If there are more incidents on the alternative route found then process needs to be repeated. Not safe while driving in my opinion.

The Navman when in "Auto-Reroute" mode seems to follow a "Robot mouse in a maze" technique.

1) Incident reported on route
2) Route clears while alternative is planned.
3) Alternative route is taken even if alternative is slower than current route + delay
3) Reroute displayed
4) There may already be traffic on this alternative so back to point 2

There are several problems with the above :

a) With much traffic on route the unit spends more time with the route cleared recalculating.
b) All incidents are avoided at all costs even if the alternative route will obviously be slower eg. Average speed of 25mph on the M25 is going to beat alternative local A roads most of the time.

For the above reasons the auto-route crumbles pretty quickly & you have to resort to warn only / manual avoid.

Do any rival TMC units handle things more like the Tom Tom? Has anyone had experience with the Sony Nav-U units with traffic? I'd heard they did a more "inteligent" comparison of alternate routes.

I wouldn't consider any units without an external FM connector.
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Navman 510

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