Real-time traffic alerts on GPS navigation systems, factory-installed or otherwise, are not all they're cracked up to be. This I can say from my own experience driving the Acura RL and the RDX on a few occasions over the past couple of years.

While the new systems purportedly offer more up-to-date information (in the form of traffic icons and differently-colored roads on maps), they still need more work. I was alerted neither to traffic jams that arose out of last-minute accidents, nor to congestion caused by long-time highway construction (as on Highway 290 in Worcester, Massachusetts, where I have found myself stuck in traffic on numerous occasions). This was particularly true on interstates outside of major metropolitan areas (which, unfortunately, is where plenty of traffic hits, especially in the summer).

Michelle Krebs drove the same cars in Detroit and reveals similar impressions in an article she wrote for the "Cars" supplement in today's New York Times (which, incidentally, also has a piece on hacked cars by Sean Captain and a handy roundup of car advice sites). She also mentions BMW's real-time traffic alerts courtesy of Clear Channel Radio, but not much detail on whether that feature is terribly helpful. As far as factory-installed systems go, I'm only familiar with the Acura first-hand, so I can't vouch for the BMW. Real-time traffic is being added to factory-installed systems on some new cars from Cadillac, Lexus, Infiniti, Nissan, and Chrysler.

All these traffic information services, whether in your car or on the Web, get their traffic updates from the same places (police reports, sensors on some highways, local transportation authorities). As a result, the reliability of the information is about the same on most real-time traffic systems (lousy for sparsely-monitored rural areas, slightly better for the 25 or so U.S. urban areas that are covered).

Real-time traffic updates have worked quite well in Europe since the late '90s, but in the U.S., these systems haven't yet hit a level of true utility to drivers, for some reason (maybe because have more ground to cover in this country). Effectiveness of traffic-jam-accuracy may vary from metro area to metro area. That said, my own experience is that I haven't had much luck averting traffic in New York, the Bay area, or Boston using these systems.

But some companies are trying to crack the code. I wrote about Dash Express a couple of weeks ago. This after-market GPS device and service uses real-time information sent in by other Dash Express owners (via a mobile broadband connection to the Internet), traditional sources (a.k.a. police reports), and historical traffic data to produce what its manufacturers' say is more reliable traffic information. I have yet to try this out either, but will report back as soon as I do. For other new traffic-detection stragegies, check out Matt Villand's piece.

Has anyone reading this actually saved time with real-time traffic features on their GPS navigation systems?