How does my car navigation thing know about traffic jams?

[Ari]

My car navigation has TMS service (I think its called). Basically it knows about traffic jams. Where they start, where they finish, even how fast they are travelling (and updates me constantly, so if one I'm approaching was crawling at 20mph and slows to 10mph it tells me). It even works out whether it would be quicker to detour round and reroutes me if so.

My question is, how the hell does it know?

[Fittster]

I thought it was by collecting mobile phone data.

Lots of mobile phones on a bit of motorway not moving = jam.

[marshalla]

Data received from various agencies is collated and broadcast over FM. Not all routes are covered as it uses a mix of live vehicle data (i.e. vehicles with trackers in them) and cameras (those blue ones). Your nav. system knows where you are and where it's going to tell you to go, so it can pick out those bits of data which are relevant to your route.

Wikipedia explanation : http://en.wikipedia.org/wiki/Traffic_message_chann...

Edited by marshalla on Thursday 20th March 09:35

[Dodsy]

marshalla said:

Data received from various agencies is collated and broadcast over FM. Not all routes are covered as it uses a mix of live vehicle data (i.e. vehicles with trackers in them) and cameras (those blue ones). Your nav. system knows where you are and where it's going to tell you to go, so it can pick out those bits of data which are relevant to your route.

Wikipedia explanation : http://en.wikipedia.org/wiki/Traffic_message_chann...

IME its also quite slow to update , you can be in the jam before it tells you about it.

The TomTom HD traffic system is much faster and more accurate. It monitors mobile phones as they move about the road network then uses that data to work out where there is a traffic jam and how long it is. Its not perfect but because of the way it collects and analyses data it certainly lets you know about jams much quicker than any other system I have used.

[Ari]

I find it's either astonishingly accurate (to the point where once, in traffic that would stop, then suddenly get back up to speed it was virtually updating in real time), or it's hopelessly wrong (it was showing a massive traffic jam near home for nearly a week once, nothing at all there!)

[Ullevi]

Ari said:

I find it's either astonishingly accurate (to the point where once, in traffic that would stop, then suddenly get back up to speed it was virtually updating in real time), or it's hopelessly wrong (it was showing a massive traffic jam near home for nearly a week once, nothing at all there!)

That's strange, I always have a really difficult time trusting this technology and tend to ignore it. Probably stems from a time when it warned to jams ahead only to be proven wrong.

I'm probably missing out on some decent redirection then.

OT Ari, a question I've been meaning to ask you for some time, I too have a late 2008 facelift SLK, probably similar to yours- black, 280 sports package with command: What capacity SD card can you use to play MP3s? I have stuck to the manual's 2GB recommendation, but do you know if you can use a bigger GB SD ?

[Ari]

Ah. Clearly I haven't read the manual properly clearly... Think it is a 32GB card in mine!

It works fine. The only thing to be aware of is that there is a maximum file number, I think it is 4,000. So you can't go sticking 1,000 CDs on it and expect it to work. Once it gets to 4,000 tracks in total the rest disappear.

You might already to this, but you can use folders with it too. I group mine into "Female", "Male", "Groups", "Various", "Playlists" (my own compilations) which makes it easier to access stuff. Also, within "Groups" for instance I can have a "Dire Straits" file with all my Dire Straits albums in (got to listen to Dire Straits if you're a middle aged man with a Mercedes! )

[Ari]

By the way - brilliant car isn't it?

[Ullevi]

Yes it is brilliant- love it! Had it coming up to 4 yrs myself and it has barely been run in- still on 14,500 miles. I have decided to drive it more, as all I'm doing it keeping it low mileage for the next owner.

I'm the one who probably misread the manual, although I will go and check ;-).

If a 32GB works, that's great. I reckon 4,000 tracks are about 18-20GB worth of data, depending on MP3 quality. I'll give it a go.

Thanks, Ari.

[Ari]

I've done 20,000 miles in mine in 2 years. I work from home so it goes no where for a few days and then a long trip. Did 600 miles in two days at the weekend and it was superb.

You're probably right about data, not sure how full mine is but I'll have a look in a bit. I have my tracks on max quality too.

Sod the mileage, just go drive it! The new model is depressing values anyway, I reckon mine's lost £7,000 since I bought it. Not selling it though so it's irrelevant.

[liner33]

Mine is linked to the car in front's brake lights , as soon as they come on it declares "Traffic problems ahead"

[anonymous-user]

Before they leave the factory, all modern Sat Navs are given "special powers" by this woman:



In fact, just out of shot is a massive pile of TomToms she needs to "empower"......


(^^^ That's all True that is)

[jon-]

Crowdsourcing cell data is the future.

Unsurprisingly google is one of the best with its own map offerings.