"T i m" wrote in message
...
On Wed, 3 Feb 2016 13:00:54 +0000, dennis@home
wrote:

On 03/02/2016 11:33, T i m wrote:


As will the Garmin ... just that I have found it has chosen the
quickest that should be the quickest, if it wasn't for the fact that
there are known 'restrictions' (like a narrow bit of road that makes
it half duplex) that slow people up, but not sufficiently to become
worthy of a congestion notice.

Tomtoms would probably have noticed if someone has parked a lorry for
five minutes and caused a 30 second delay.

How though?

They do it by monitoring where the tomtoms are using
the associated smartphone or the SIM in the tomtom.
So if someone using a tomtom goes down that road,
they see it get delayed. Obviously there needs to be
more than one seen to do that for it to be other than
just stopping to perve at someone streaking etc or
Dennis out and about looking like a silly old fart
booking someone for exceeding the speed limit.

I know there are traffic monitoring cameras on some main
routs (typically on motorways etc) but how would anyone know
a lorry was caught up down some side street used as a rat run?

By seeing the effect on tomtoms going past.

Nothing like as good as the google system which keeps track of
mobile phones moving on the roads using data from the mobile
phone bases which can see all phones in their area.

I have been notified of 30 second delays while out and about.

Yes, me too, but only when on major routes and that's not necessarily
the same thing as being informed about a delay that has only been
there for 30 seconds or five minutes, specifically if not on a
monitored route or it not impacting a monitored route?

The only way I could see that sort of thing working would be if the
GPS was able to compare your actual speed with the theoretical and
reported_by_others_recently speed for that route and upload that
discrepancy to some network and then update all the other units
(like you can with some speed camera warning devices).

That's close to how it works.

I mean, if a particular bit of 30 mph road was only / ever 15 mph
because a restriction made it half duplex, it's quite possible that
information could be collated by many peoples track logs

Yes.

but that wouldn't be so likely to predict a broken down lorry making it a
little bit worse?

It clearly does for a while if enough tomtoms pass it slower than normally.

Unless it can (and I'm not saying it can't etc) ... if it was linked
into a real live traffic network using two way data from many
GPS units (or phones)? shrug

And that's what happens.