How does the Sat Nav Pro in my E93 know where the traffic jams are?

[wax lyrical]

Little black arrows appear on trunk routes that indicate traffic jams/ slow traffic - but how does the car know??

Thanks in advance!

[BEEMER69]

I assume it's using TMC (Traffic Message Channel) which is received by your radio.

[philmots]

Some get the information from road sensors etc which go to a central point then out to your Nav, various websites etc..

I know TomTom uses a system where it gets data from GPS signals from people's mobiles. So of there's literally millions of data inputs so queue times etc are very accurate.

[technogogo]

More information: http://en.wikipedia.org/wiki/Traffic_message_chann...

[RicksAlfas]

BEEMER69 said:

I assume it's using TMC (Traffic Message Channel) which is received by your radio.

Yes. TMC shows in a little info box on the navigation screen. It can also bring up warning triangles to show traffic lights are out, car accidents and so on. Not foolproof but has helped me a few times.

[Kuroblack350]

wax lyrical said:

Little black arrows appear on trunk routes that indicate traffic jams/ slow traffic - but how does the car know??

Thanks in advance!

If you set up the right hand side of the screen as 'traffic overlay' I think, (on Pro Nav) it gets better, it overlays all roads with a Red/Amber/Green system according to traffic flow - really useful.

Have to admit I'd assumed this functionality was part of the internet access option and that after three years I'd have to renew the subscription - maybe not then? Not surprising if I've got that wrong, only just realised the system will not only display, but read my text messages - cool

[Trigbert]

Spookily enough was asking google the same question this afternoon, looks like depends on age of car. Was TMC now using mobile phone since 2011

http://www.roadandtrack.com/go/news/new-technology...

Mine M3 is 59 plate so must be TMC, but works really well on a journey.

[HoHoHo]

Old TMC uses a second radio antenna in the car and the preferred station which sends information to the car is Classic FM which is a UK wide station.

Roadside sensors relay information to a single source which then transmits through the FM frequency to your car. Simple coordinates of traffic issues are then shown as marks/arrows on your map.

With mobile phone technology this is all changing though.