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One of my favorite features is the traffic info that is built into the nav system. I am curious as to how it works. Is it based on syndicated traffic reports from local channels, etc, or does it receive parameters such as speed and location from the traveling vehicles, in order to determine where the trouble spots are?
 

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The information comes over a radio signal. Typically just the major roads are covered.
 

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One of my favorite features is the traffic info that is built into the nav system. I am curious as to how it works. Is it based on syndicated traffic reports from local channels, etc, or does it receive parameters such as speed and location from the traveling vehicles, in order to determine where the trouble spots are?
I've heard that they are working on that idea. It's certainly not available in the US yet. I could imagine that there are privacy issues with collecting that kind of data. I don't know if it is available in any other market (Germany?). Right now in the US it's just a radio signal and no individual car data.
 

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It definitely works on the information transmitted over radio. It's disappointing, as it advises you you to leave the main road just to get you in a traffic jam on the secondary roads where there's no info transmitted. Don't blame BMW, sooner or later the info on minor roads will be added... I assume later rather than sooner...
 

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Having lived in SoCa most of my life, I find that continuing on a jammed freeway caused by an accident is faster to your destination than trying to find an alternate road because everyone is doing the same thing. Unless the freeway is completely block, it is wiser to stay on the freeway.
 

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The RTTI isn't so accurate here in Portland, OR. It's always delayed by about an hour or so and hence off by about 3+ miles most of the time. So, I just use it as a guide, but it does help if there is a complete block of if I5 has went from 5 to 1 lane.
 

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RTTI - Main Roads Mostly

The information which feeds the BMW NAV computer is produced by a Clear Channel Communications division called the "Total Traffic Network." See their not-very-helpful URL here: http://www.realtimetraffic.net/ In practice, the information about traffic, from whatever source, is sent out in bursts of information via the RDS systems of various radio stations in the metro area in which the vehicle is located. Rural areas are not covered for obvious reasons.

The real question is the source of the information. I believe I read a news item (probably based on a press release) that the information was eventually going to be provided through a variety of sources...government data, motorist observations, and (here's the good one) through reports gleaned from GPS-equipped commercial vehicles sending information back (without the knowledge of the operator) of slowdowns on particular roads.

In practice, BMW NAV units, and Garmin units (with which I'm familiar) use the "Total Traffic Network" data. Around the Northeast, the main roads are covered well, but the data is sometimes slow to update. Two examples: 1) I was driving yesterday on I-95 in Rhode Island in the midst of what was supposed to be a major jam, and moving along at 60 mph; and 2) About I had the experience of being caught in the middle of a major jam on the GW Bridge from NJ to NYC, with my unit indicating no problems. Right when I got in the middle of the bridge, my unit must have received a burst of info. from the system, and suddenly I learned the GW Bridge was jammed. That said, the information sometimes has saved me from hours on the I-95 parking lot in Connecticut. Perhaps it's not as efficient on the weekends...I dunno.

Until the system becomes more sophisticated, I believe that local knowledge of side roads, shortcuts, etc. is going to be more useful. Soon enough, everyone will have a GPS unit in the car with RTTI, and as others (above) have noted, we'll all be taking the same shortcuts. Perhaps the system is better in Europe?
 

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I've heard that they are working on that idea. It's certainly not available in the US yet. I could imagine that there are privacy issues with collecting that kind of data. I don't know if it is available in any other market (Germany?). Right now in the US it's just a radio signal and no individual car data.
It became available in the 2008 models as part of the NAV system and I have it in my 550. As noted by others, there is a section in the NAV system that identifies all traffic updates that it receives through the RDS signal. In the New York City metro area, it lists updates as far away as Philly. If you have a route programmed in the NAV, the system automatically identifies delays on your route and, if the delay is significant, it will tell you how far away the delay is, how long it is in terms of miles and time, and ask if you want a detour. If you select the detour, it will re-route the next fastest route while also factoring in other delays in the area.

I have found that the coverage of secondary road delays is very good in the New York City metro area, specifically on long island. As an example, during the flash flooding we had on Wednesday, July 18, the detour off of the LIE and Northern State also routed me off of routes 106 and 25 because of flooding on those secondary roads. It also routed me around Jersey turnpike delays on two occassions the previous week. By contrast, secondary road coverage was hit and miss when I drove down to DC, and non-existant in most of connecticut.

All things considered, it is a great feature if the local infrastructure supports real-time traffic info. If you don't live in a major metro area (e.g. one where every radio station is giving a traffic update every 5 minutes during morning/evening rush hour), then it probably won't be a useful tool except on the main highways.
 

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Stuart in Houston
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One of my favorite features is the traffic info that is built into the nav system. I am curious as to how it works. Is it based on syndicated traffic reports from local channels, etc, or does it receive parameters such as speed and location from the traveling vehicles, in order to determine where the trouble spots are?
Actually, in Houston, we have a real time traffic map that is based on individual vehicles. But it is aggregated, so no privacy issues.

The local transit agency uses the electronic toll tags (called EZTag here) in cars. They set up toll-tag reading devices on all the major freeways. It reads the tag as you pass each device, and thus can deduce the average aggregate speed of that freeway. There are so many people with tags here (very large percent) that it works well.

http://traffic.houstontranstar.org/layers/
 

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Yesterday, I was enroute from Northern New Jersey to Wlmington, Delaware. As I passed Exit 7 on the New Jersey Turnpike, my Nav System announced that, due to traffic congestion ahead, I was being rerouted. I noticed that the "i in the triangle" was now bordered in red, and I clicked on it to see the details. It informed me that, due to construction between exits 6 and 4, there were delays of 21 minutes. Since I had elected "dynamic routing" in my i-drive, it showed me my new ETA, now 9 minutes later than prior to the announcement. I followed Olga's directions, and got off at exit 6 and wound up at my destination at just about the same time as my original ETA. Everything worked out fine, but in retrospect, I might have been better off sitting through the 21 minutes of delay rather than putting on all those extra miles.
 

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Always use a 2nd source

Due to the delay in some of the traffic information getting updated, I find it important to always get a 2nd opinion on the traffic data.

If I see a delay on my NAV system, I always try to verify it with a traffic report from a local news station or from SIRIUS.

I have found that this approach usually works the best. Sometimes the NAV system gives "false alarms" and will re-route you for very small stuff.

Overall, I think the RTTI is fantastic and has saved me countless hours. For example on a Saturday afternoon on the way down to Philly from Northern NJ, the NJ turnpike was backed up for five miles around the car / truck merge. The RTTI rerouted me to Route 1 and I still made it to my destination with plenty of time.

Jeff
 

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It became available in the 2008 models as part of the NAV system and I have it in my 550. As noted by others, there is a section in the NAV system that identifies all traffic updates that it receives through the RDS signal. In the New York City metro area, it lists updates as far away as Philly. If you have a route programmed in the NAV, the system automatically identifies delays on your route and, if the delay is significant, it will tell you how far away the delay is, how long it is in terms of miles and time, and ask if you want a detour. If you select the detour, it will re-route the next fastest route while also factoring in other delays in the area.

I have found that the coverage of secondary road delays is very good in the New York City metro area, specifically on long island. As an example, during the flash flooding we had on Wednesday, July 18, the detour off of the LIE and Northern State also routed me off of routes 106 and 25 because of flooding on those secondary roads. It also routed me around Jersey turnpike delays on two occassions the previous week. By contrast, secondary road coverage was hit and miss when I drove down to DC, and non-existant in most of connecticut.

All things considered, it is a great feature if the local infrastructure supports real-time traffic info. If you don't live in a major metro area (e.g. one where every radio station is giving a traffic update every 5 minutes during morning/evening rush hour), then it probably won't be a useful tool except on the main highways.
Correction: It became available in late 2007 with the NAV as an added bonus for buying the NAV system. I have it on my 07 550i that I took delivery of in October of last year. I believe that their original intent was to let it out and create a desire for the product then start charging for it as an extra. My experience with it has not been very good. I live in the South Florida area in the Winter and in Michigan in the summer and the information it provides is inaccurate about 95% of the time and the rest of the time it doesn't know about the problem. Once while driving from my home near Boca Raton to Miami it found a traffic obstruction and tried to reroute me all the way back to Boca via 441 (about 20 miles) and then back to Miami. Until they can improve the technology I'd say avoid it. If it's for free than that's okay but I wouldn't pay a nickle for what I've seen so far.
 

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RTTI is never accurate in NYC Area

I drive thru Queens up I 95 thru the bronx and up to Greenwich CT every day. For all you NYers you know what a major artery that is.

Here is a very typical daily RTTI situation.

The NAV RTTI shows heavy traffic...the news radio says clear sailing, sure enough no traffic. NAV is incorrect!

The NAV RTTI states no delays...OK...I'm feeling good about it..Si I trust it..(bad move) the road is JAMMED!! Again NAV is incorrect and I am pissed sitting in a long traffic jam.

Only if the traffic situation is terrible and there has been bad traffic for hrs will the news radio and RTTI be in sync.

Most of the time it is worthless. The data is very lagged! It is not real time...it really should be called VIADTI (very delayed and inaccurate traffic information) :(

Just listen to the traffic report on the radio and you'll save yourself alot of grief. ;)
 

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It's far from perfect, but I find RTT performs better on LA freeways. I'm glad that I have the feature, but always ignore the rerouting instructions since surface streets aren't covered.
 

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I am currently testing a GPS Dash.9 with that feature.

I am one of 2000 drivers selected to test a unit called the Dash.9 that has many interesting features. One of which is the traffic feature. I cannot share much information but it looks good. My 05 530i nav system does not have a traffic feature. I believe the traffic information is shared by detecting drivers speed at certain locations and certain times.
 

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I've heard that they are working on that idea. It's certainly not available in the US yet. I could imagine that there are privacy issues with collecting that kind of data. I don't know if it is available in any other market (Germany?). Right now in the US it's just a radio signal and no individual car data.
A little past test data at this point. Inrix´ data became available through Clear Channel at the beginning of 2007 and it taps into the 'Smart Dust Network,' which intelligently combines the largest GPS-enabled vehicle probe network in the world with speed information from conventional road sensors and numerous other sources.

It became available in the 2008 models as part of the NAV system
Not correct. No changes for 2008 for the satnav system. But Inrix´ enhanced data became available to all RTTI users as of Jan. 2007 via Clear Channel. (See above)
 

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It worked superbly for me in Germany on the autobahn between Munich and Salzburg. It worked beautifully and was quite accurate on two occasions. It is great technology dependent on the quality of the the information that is input into it.
 

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Two Systems

I have traffic from Clear channel in my 2008 BMW. It is rather worthless in the NY area since it does not update in a timely manner. I have a Garmin 2830 (something like that) with XM radio and traffic that uses data from Traffic.com to stay updated. This system is excellent and is correct most of the time. The unit has been discontinued and I am not sure if any Garmins still use XM radio for there traffic signal but this system has been much more reliable then the Clear Channel System. There also seems to be no progress by Clear Channel to improve the system. Xm keeps getting better and includes most major construction.:mad:
 

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I have traffic from Clear channel in my 2008 BMW. It is rather worthless in the NY area since it does not update in a timely manner. I have a Garmin 2830 (something like that) with XM radio and traffic that uses data from Traffic.com to stay updated. This system is excellent and is correct most of the time. The unit has been discontinued and I am not sure if any Garmins still use XM radio for there traffic signal but this system has been much more reliable then the Clear Channel System. There also seems to be no progress by Clear Channel to improve the system. Xm keeps getting better and includes most major construction.:mad:
RTTI is largely useless in Seattle area. Only covers major highways and hopefully out of sync with reality.
 
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