After publishing my review on the Garmin Nuvi 680, a few people have written in about the topic of traffic suppliers and traffic alerts. It happens to be a favorite topic of mine because I hate sitting in traffic and I can see where this is all going and I am pretty excited about the possibilities. First let's take a look at the two major traffic systems that are available today.
Most GPS systems use the TMC traffic system that is fed over the FM air waves by Clear Channel Communications. The data is fed by Inrix. I have written a lot about Inrix, and their miles of road covered is claimed to be superior to Traffic.com's. Check out how Inrix collects more information about roads that don't have expensive installed sensors; it's called the Dust Network, and it's pretty innovative. The recently announced Garmin Nuvi 680 uses MSN Direct Traffic. MSN Direct uses Traffic.com's data (being acquired by NAVTEQ), which relies on road sensors for the most part to gather information about traffic flow and incidents. They are not ONLY relying on road sensors, as they too are getting into using fleet vehicles and anonymous cell phone monitoring.
So, while Inrix talks about more coverage, Traffic.com talks about quality of data feeds. I live around Boston, and the MSN Direct service does not yet cover the roads in my area (Second Beltway around Boston), so this is a concern for me. Coverage may be a concern for you too. You can compare the coverage for your area at Inrix or at Traffic.com. At Inrix, just click on your city to see a what roads are covered in your area. At Traffic.com, click on your city and then on the Map tab to show the coverage graphically.
Don't walk away from the Traffic.com fed MSN traffic yet. The data feed coming from Traffic.com, as shown on the Nuvi 680 tells you anticipated delays along your route, where speed data is given. So something like: "2 incidents on your route. 15 minute delay." I like this, as it informs me about what is going on and how much trouble I am in for. The trade-off here is coverage, for what is a pretty useful feature in my mind.
I would imagine (hope) that Inrix could flip a switch on the data format to provide this type of information, but I can't really say. I also can't say what's better for you, as you'll need to check coverage maps at both Inrix and Traffic.com to see if your route is covered on a daily basis. I would urge you to check coverage, and then consider how much you'll use the other MSN features (like the money saving gas finder), and make your decision.
When I was driving up to Boston during one terrible rush hour with the Nuvi 680, it didn't actually warn me about trouble ahead. I was curious why. The highways were all snarled with "RED" colored traffic, and I combed the route to find that it routed me around the trouble spots right from the start. It still took me a bit to get around on the surface roads, but not nearly as long as sitting in the mess on the interstate. Pretty good.
All of this traffic stuff is getting ready for a big change. There are a few developments that are coming in the very near future that will dramatically improve the situation. The issue is that these improvements will most likely not be compatible with all of the GPS units of today. For more on the coming traffic feeds improvements see my post: The Coming Wave of Better Traffic Reporting in GPS Systems.