With NAVTEQ traffic coming to the Garmin nuvi 2x5T and 7x5 series, it's a good time to look at the coverage of the five major traffic providers in the U.S. Live traffic information is far from perfect, though it can save your bacon occasionally. But first you have to be in an area with reception. So let's look at their coverage maps, and then I'll turn it over to you, our readers, to hear about how accurate these maps are (or not!).
Going by two monikers, the Total Traffic Network from Clear Channel and the broader term TMC, this service is distributed via FM RDS. Currently coverage is offered in 85 metropolitan areas, but they haven't updated their map (shown below) to include the 15 newest cities. Detailed coverage maps of most metro areas can be found on Garmin's website.
MSN Direct traffic
Microsoft's MSN Direct service offers traffic coverage in 86 metro areas in the U.S. and three cities in Canada, with non-traffic coverage offered in 43 other North American cities. In my experience in multiple markets, their detailed coverage maps (one is shown at the top of this post) significantly overestimate their reach.
The provider of Garmin's new ad-supported traffic service, NAVTEQ offers coverage in only 50 U.S. cities and Toronto, Ontario. Like FM/TMC, NAVTEQ Traffic is also delivered via RDS. Detailed coverage maps are available on the NAVTEQ website.
I find XM NavTraffic to be interesting ,since they say that NAVTEQ is their traffic provider, but with 77 cities in the U.S. and three in Canada, they offer significantly more coverage than NAVTEQ Traffic (discussed above). Follow the link for detailed maps of each area.
TruTraffic (Dash Express)
Dash Navigation's TruTraffic is a special case. It uses INRIX data to provide coverage for 120 metro regions, but it also utilizes anonymized data from Dash owners.
Dash uses Jasper Wireless to transmit traffic data via cellular signal, but the coverage map below only indicates cellular signal reception, not availability of traffic data (I'm bolding that so as not to mislead anyone). Where Dash has an adequate user base, traffic data can be significantly better than that of the other services.
Just how accurate are the traffic providers' detail maps for a given metro area? Who is overestimating coverage and who is understating it? Chime in and let us know what your experience has been.