Understanding GPS navigation traffic services

Consumer Reports News: December 23, 2007 12:08 PM

Finding the right route to your destination is only part of the challenge with a road trip, be it daily commuting or a long-distance vacation. All the planning in the world can't account for sporadic traffic congestion. As any portable navigation device (PND) shopper soon discovers, there are traffic services available for GPS units to warn of imminent slow downs and even route around a problem area.

Adding true value to the basic mapping functions, traffic services can make a GPS unit a helpful travel companion on even familiar roads. However, not all traffic services work in the same manner. Before committing to a purchase, it is important to understand the differences.

There are three basic ways to receive traffic information:

Bluetooth—The navigation device uses your cell phone to receive the traffic information, which is beamed to the unit via Bluetooth technology. This method effectively requires your cell phone to have a data package, as a constant connection is needed to ensure continuous updates along your route. There are a limited amount of compatible phones, almost exclusive to T-Mobile and Cingular. TomTom units use this approach for the TomTom PLUS services.

FM—Using the same FM Radio Data System (RDS) that delivers station IDs and song information to modern stereos, sources like Navteq and Clear Channel Radio deliver traffic updates over the airwaves. An external antenna may be optional to assist with reception. FM traffic is most often a premium service, although some devices, like the Garmin Nuvi 265T and Navigon 7200T, include it for free.

A new twist on the traffic sources is MSN Direct from Microsoft. An FM-based service, MSN Direct is available on just a handful of models out of the box and several more are compatible with the purchase of an additional FM receiver. This service combines traffic information with weather, movie times, and gas prices. It costs $49.95 a year, or $129.95 for the lifetime of the device. It is non-transferable.

XMXM NavTraffic is a premium service powered by Navteq. Plans allow for a$9.95/month stand-alone fee or $3.99/month when combined with XM Radio service. Some portable devices can be used to bring XM Radio service to the car, played through an FM transmitter. While convenient, this may not be the ideal solution for audio fidelity. FM transmitters run the risk of station overlap in major metropolitan areas where the services are most likely to be available. XM requires an antenna.

Living with traffic
With a traffic service, the navigation device will receive periodic updates based on your driving path or (if entered) programmed destination. It can provide on-screen alerts and even indicate the traffic flow rate. Usually the driver can tap a traffic icon to receive info on how long the delay is, what type of obstruction (accident, construction, lane closing), and then decide whether or not to detour around a trouble-spot.  Also, general traffic in the area can often be displayed by going into the menu of the unit and just browsing the traffic incidents.

While we do not specifically test traffic performance for our ratings (available to online subscribers), we certainly have used the functions as we drive around the New York City region. The major providers have coverage in about 80 major metro areas, covering the bulk of the nation's congested areas.

Drivers benefit from these services by receiving only the information appropriate to their route, rather than having to filter through periodic, on-air traffic reports. Such radio updates tend to focus on major trouble spots and may not address the road you're on. In New York, for example, it is not uncommon for reports to be focused on the city bridges and New Jersey, areas far from where we may be driving.

Like traditional radio reports, the traffic services can be spotty and experience time delays before some information enters the corporate system and is fed to your device. A week ago, I was in bumper-to-bumper, walking-pace traffic on an Interstate for an hour before the nav system indicated a traffic slow down. ("Gee, you finally noticed," I thought.) On the other hand, driving on a smaller parkway recently, I was impressed when the same device warned there was a disabled truck just moments before I saw an 18-wheeler at the side of the road with flares around it.

Traffic services can be a real convenience, and even a time saver, but they aren't  perfect. They can, however, add value to your GPS purchase by making it more useful on a daily basis. If you are drawn to a traffic service, look at all the costs associated before choosing a device. Many systems are "traffic compatible" but require a $125 receiver. That may be money better spent on a more feature-rich unit or even one with a wide screen.

Just as with the device itself, consider how many features you will truly need from a traffic service. If you buy gas at the same local station and look online for movie times, for example, you may be able to forgo MSN Direct. Likewise, if you don't think a traffic service is truly worth paying for, put the money toward a better, non-traffic unit, or just keep it in your pocket.

Jeff Bartlett and Frank Spinelli

Updated 12/12/08

For more information on portable GPS navigation systems, see our Ratings and buying advice and watch our video guide. Discuss GPS devices in the forums.

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