GPS Devices w/Traffic Info - How Do They Work?

My Google searches haven't helped at all. I'm just looking for really basic
info about GPS devices with traffic info. 1) Do they route you around
traffic problems or just warn you of problems? and 2) Where do they get
their traffic info from? I know that they get it from an FM source but
where does it originate? Does the info rely on someone in a traffic jam
phoning in that info to some central clearing house?

Thanks, Bob

On Sat, 17 Jul 2010 20:44:25 -0400, eBob.com wrote:


Either. Both. Depends on the circumstance for a lot of the devices: That
is, IF you have them set to avoid traffic AND the delay is enough to
justify taking another (usually slower for one reason or another) route,
then the route may be recalculated. If you haven't told it to avoid
traffic, but tiem is VERY delayed on that route, then it might re-calc
as well. If you're on a "prefer shortest", or aren't following a route
at all (just driving) then it will probably just warn you.


Usually there's an automated system run by the local government that
counts cars and speeds they pass, either on a video feed or by induction
loops in the pavement. Then the local Dept of Transportation publishes
the data in some form, and the services pick it up from there and
broadcast to the recievers.

--
With a Dremel tool and a cut-off wheel, _everything_ takes a flat-blade
screwdriver.
                         -- Matt Roberds in the Monastery

        I don't think it's what the traffic services GPS owner are getting. Right
now we are limited to around 2 private systems (it could be more?) FM
Traffic (I may not get the correct name) and one runs by MicroSoft (MSN
Direct Traffic?) which will be ended very soon.

        They don't place a hole with water connected to a metter to measure the
number of car passing through which is local government use. I believe the
traffic serices recieve information from the reports of local (like news,
local transportation) then update to their database. Then

1. The information only available if it's in the database

2. The service only available if they have station (transmitter) available
to send out the information.

        I happened to have a chance to use both MSN and FM Traffic, and I can tell
you that with

MSN        - I only recieved the accident report ONCE, and hi-way repair ONCE even
the road repairing last for almost a month (I have passed thorugh it more
than dozen times).

FM Traffic - Since I only have this service for 5-6 months. So far, I have
noticed the ICON changed from GREEN to BROWN few times which means slower
traffic, but haven't run into RED color yet.

        The FM Traffic not available on all cities but pretty limited, I have
driven to other states and I have noticed the ICON disappeared on Intersate
and Hi-ways, and not available on many cities, town etc.. I drove pass few
states capitals and no service available (the Intersate hi-ways were passing
through inside cities not miles away).

        In general, the TRAFFIC won't change anything but reporting the condition
so YOU can decide if you want to go around or go straight to whatever
traffic report.

        Example, if you are normal traveler then you may want to tell your GPS to
go around the accident (for example) and it will do what you tell it to do.
And if you are News Reporter or Police then you may just continue to the
accident to SNAP SNAP some photo to send back to NEWS statation.

        Same with other feature, some report the WEATHER and if it reports RAINING
then you have option to continue driving or stop by a restaurant to wait for
the rain to stop etc..

        The GPS get traffic information from the Traffic Service

        Even you pay for the Traffic Service you won't get the traffic information
in state or city that has no service. Or it's only available whereever the
service is available.

        You don't need to know how they get the information, but only know if the
infomration is available or not.

        Samething, I don't need to know where your message come from, I only know
it's available on my screen and I response to whatever I know. Mine may be
the 1st one and can be the last one, and who knows someone may correct me
without giving you any correct info. That's similar to the Traffic Service.

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I get traffic on my 1490T but generally it doesn't tell you how far
ahead the bottleneck is (one time it was 20 mi down the freeway! but
it said "Heavy traffic ahead" as soon as I entered the freeway).

It warms you about traffic congestions along your route but fails to
pinpoint the exact parts.

In the end, I have to rely on the old fashioned traffic radio to tell
me the exact sig-alert locations.