TMC and streetpilot and automatic re-routing...

[Lester_Burnham]

I've been using my TMC equipped (GTM-21) C5xx series for a good few months, now, and in recent times, most days.

Before now, whenever TMC / the GTM spotted a delay on-route, it would just display the delay time in a red triangle in the bottom right of the screen. If I wanted to use this, for an alternate route, I've always had to click on it, and have it avoid it (ie recalculate an alternative).

This morning, it spotted a reasonble sized delay, initially starting at 7 minutes, then growing to over 30 minutes (I think), then it did something I don't believe I've witnessed - it automatically changed route and recalculated. I think the TTS voice said something about recalculating and "traffic".

Anybody else find this - ie it will on occasion automatically re-route, or you have to actually click the delay and get it to do so? Is it an impending doom thing - ie the nearer you get, or a delay thing (ie over a certain amount of delay and it does so automatically), 'cos I don't think I've experienced it do so of it's own back, previously.

[PaulB2005]

I think i had this happen once before however driving down the M1 last weekend i hoped (in a funny sort of way) it would do it again...... but it didn't....

I have noticed (when playing about with the TMC on my drive) that sometimes when you select Avoid it states the "Optimum Route is already selected. Do you want to re-route" so i suspect when the delay changes the unit calculates an alternative route in the background. If the current route plus the delay would take (significantly)longer than an alternative route (because sometimes sitting through a short delay can be quicker than the alternative route) then it'll automatically re-route, otherwise it'll still take you through the delay.

[Lester_Burnham]

There may have been some oddness or maybe a un-typical start of the route for my journey, today.

Normally when I set off, TMC has not established TMC reception / info before a route is calculated, but today, it had TMC reception for a while before I entered my destination.

Now it can calculate 2 very similar routes, using different motorways to my destination. I hadn't noticed, but today it had calculated the other, non-typical route selection (it doesn't normally do this, although previously, my i3 could flip-flip between the two alternatives). The factors that may have influenced this being it had TMC reception for a while before calculating the route, and my start point was slightly different (I waited until I'd filled up with petrol before having it calculate my route).

When it did dynamically change the route (I'd noticed some minutes previously, that it was directing me on the unusual route) it directed me to the normal route option.

I guess it was the dynamic bit that suprised me - I've never encountered it doing so previously, I've normally had to pursue the alternate option by selecting it - I was just curious as to whether it had been established as to when / how it does it dynamically.

It seems to be shrouded in some mystery ;-)

[inspiredron]

TMC will re-route you if it saves time. I have had it happen many times. You also have the option to manually avoid.

[Lester_Burnham]

[inspiredron]

[Dabri]

Hi,

I have twice recently had a similar automatic rerouting when the displayed delay was approaching 30 minutes whilst travelling south on the M5. The 'problems' were [1] roadworks and [2] a large, slow moving lorry. Initially I was happy to accept the reroute (which was about ten miles in front of me) until I heard on the radio traffic information that the lorry had stopped for the night at a service station. I waited for the 760 to remove its reroute on its own, but it didn't until I stayed on the motorway (it wanted to get off onto A roads) and it recalculated. It got its own back on me later when I hit heavy traffic at the road works, which it did not even mention when it recalculated! My point is that the unit did auto reroute, which is fine, but does ot seem to check when 'problems' disappear and the reroute is inappropriate.

[Lester_Burnham]

Just as a little more feedback to this, it happened a couple of times this morning - and the TTS voice said something like "Severe traffic ahead" or "Severe traffic delay ahead" followed by "Recalculating".

I'm not so sure it was clearly related to the time it was showing as the delay - because it didn't look to be that bad, so it must be related to some degree of severity that the delay is classified as.

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