Nuvi Traffic - Condition Green

There is no congestion on that stretch of road. It's clear at the time of the report.

Probably because no data is available.

Again, probably no data to update you with.

Traffic data is broadcast via FM radio signals so if you are not in an area covered by a traffic service, which are usually larger cities, your seeing the green icon because your Nuvi's traffic receiver (power cord) is picking up the signal of an FM station that is broadcasting this data.

I live in a area not covered by a traffic service but often pick up a signal from one or more FM stations about 40 miles away in a covered area. I tap the traffic icon and I can see that it's reporting on conditions in that city.

Yes I understand where the data comes from, but my question is about why a few very select portions of roadway (usually very short) are selected from a few arbitrary roads to be green, while the rest is blank. This is for a major metropolitan area with excellent RDS signal and lots of Interstate.

I wouldn't expect the RDS system to attempt to send data for fluid conditions as bandwidth is extremely constrained, it makes sense to concentrate on the trouble spots. So how do they choose a few miles here and there on a few very random freeways to be green?

So are you saying that Garmin/Navtech/CC intends to mark all portions of covered roads in a covered region to have a color? Given the paltry bitrate of RDS, that seems like a pretty tall order... Why waste bandwidth to mark a few tiny sections of roads green, when the system struggles to push data about trouble areas?

I was merely suggesting that where data is available for those areas, and stretches of road, you'll get the conditions.

All of it depends on the frequency of updates from the provider of the service.

To clarify, I am talking about Interstate class freeways in major metropolitan areas well within the coverage areas. There will be 2-4 random sections of freeway (1-3 miles long) scattered around the entire metro areas that are marked green. How did they choose to make these areas green as opposed to others? And why bother pushing "green" data over a severely constricted data link anyway, unless the green areas are to cancel previous trouble (red/yellow) areas?

The traffic received on Garmin GPS is same as shown on NAVTEQ website. On website; it shows green where the flow is good but GPS in my city doesn't follow same process. It only shows where there is a delay. If there is a good flow; the gps doesn't bother showings..

I wish garmin uses traffic from google; it is a little better than navteq..

The map coloring was an issue brought up by the developers of MSN Direct regarding limitations of RDS Traffic (see page 2 of http://www.msndirect.com/RDS_MSNDirect_Comparison.pdf):

Basically with RDS, as long as a road has no coloring it is either not covered by traffic information, traffic is flowing normally or you have not yet received an update for that particular stretch. Green under RDS is supposed to mean some kind of traffic activity in that area but it is minor.

Now under MSN Direct, all covered roads were marked with color just like on Bing Maps or Google Maps. Green is normal flow and and yellow/orange/red indicate different levels of severity. MSN Direct's argument was that with RDS you could not tell if a particular road was not covered due to no coverage by the provider or failure to receive an RDS update for a particular stretch of road. RDS transmits one TMC message a second and at best you could get 60 traffic information points in a minute (much less due to other RDS information being transmitted during that period). However, with MSN Direct shutting down in six months, it all goes away.

It's only my guess, but in my area there are known bottlenecks where portions tend to back up when it's rush hour or during scheduled road work. I would assume that the green sections indicate these areas are clear. I wouldn't expect the entire road to be green if everything was 'normal', but I'd want to know if these sections happen to be or not.

I like to think of the green sections as a confirmation that the section is monitored and it's reported clear, rather than no indication at all and I don't know that it's being checked or not.

[edit-] Re-reading Aardvark's post .. yeah, what he said

I am aware that MSN is a mute point as of the end of this year, however I have encountered some areas here in Ohio that are perpetually encountering traffic issues whether it is rush hour or other times of the day.
It continues to say traffic congestion ahead regardless of the time of day???

With my 855 and Navteq traffic, Green does seem to indicate some kind of minor traffic activity. I have menu at the bottom of the traffic screen which allows you to display by road. My recollection is that when you display by road you can click on an item in the list and it will provide additional information, usually indicating that some hazardous condition exists.
Mark

I have the Garmin 3790LMT and GTM 35. I have both the free Navteq and paid-for Clear Channel traffic subscriptions. I noted that I have only yellow and red traffic flow indicators.
I am in Louisville, KY. I rarely might see green for roads that are otherwise typically red/yellow (to show is is better than normal). In all cases, the flow lines are narrow and very hard to read. The default theme is "orange roads", so I changed that to British Blue for better contrast.
[My old MSN Direct Traffic map showed all area highways and some secondary roads as green, yellow, and red. It also meant you knew where there was no coverage.]
This Navteq/Clear Channel method is clearly inferior, and I am disappointed.

There used to be a Microsoft document that discussed this at http://www.msndirect.com/RDS_MSNDirect_Comparison.pdf but it has been pulled as MSN Direct is no longer around (I did happen to keep a copy of it when it was available). The relevant part of the document follows:

MSN Direct showed green where data had been received and traffic was normal. Under RDS, you will see nothing which either means traffic is normal or data has not been received.

I was on Clearview Expressway last night and my Nuvi said there was traffic ahead. I decided to risk it and it was clear sailing, no traffic.

I believe there is also an issue when DOT authorities provide info as a general alert and it is posted by NAVTEQ as if its an actual traffic event. For example, evidently Maryland DOT distributed a general alert for overnight overpass maintenance on BW Parkway and for drivers to expect up to 20 min delay. So when I plotted a route from DC to Balt anytime that week it would show a 20 min delay in that area, even though each day when I drove there to the actual area it was free-flowing. So my experience has been the FM traffic in DC / Balt is of little value

I also notice that when I input the destination, the time of arrival is as if there is no traffic. Then when I actually get on the highway, the ETA changes to reflect the traffic, when I can't do anything about it.