lane accuracy of 3597

Unfortunately, consumer grade GPS devices are not designed to provide pinpoint accuracy.

http://www8.garmin.com/aboutGPS/waas.html

I understand that Nuvis and such have a "Lock on Road" feature that is always on. That is, you will always be shown as an a road, however the algorithm sometimes picks the wrong road, especially if you are on a service road parallel to some major roadway. Some more universal GPS's such as the Montana allow you to turn off this function. An interesting feature of this function is that it may show you on the origional path of a road that has moved due to construction but the track will in fact show the real course followed.

According to your profile you have a 3597 and a 3790. Does the 3790 display the lanes any differently than the 3597?

I have both units and personally I have not noticed much of a difference, but I don't use the 3790 much anymore. I will agree that the maps don't display the HOV lanes on most highways but I've long since got used to that.

That would be nice - would also be good to be able to tweak the speed limit signs on the Garmin (can't on my unit).

Garmin give'th and garmin take'th away

I have an older Nuvi 1450 and it behaves exactly the same way - it doesn't/can't distinguish express lanes versus regular lanes. It's probably an accuracy thing.

Phil

the feature is usually helpful; but on elevated ramps, the garmin sometimes picks up (and displays) the street or lanes BELOW.

ouch.

I just ordered a 3597 and am looking forward to trying the active lane guidance feature. I hope that doesn't happen frequently.

Got a few thousand miles on my 3597, mostly on the west coast and Arizona. Have never had this problem with the 3597 on elevated ramps so you are probably good.

If you just turned on the machine while (unwisely) standing in the criss-crossing roadways of a major interstate exchange it would quite likely guess wrong as to which road you were on.

But in the real case of interest, in which you approach the intersection in a vehicle travelling along a road, the software assumes you are continuing on that bit of pavement until the discrepancy between your detected position and progress along that road is larger than some threshold. If you are being actively guided, then it assumes you take the path suggested which helps resolve the question as ramps diverge.

So as a practical matter, you are not likely to see lane guidance trouble from this cause unless you are in tunnels or such.

Anyone from Boston care to comment on how their Nuvi works in the Big Dig tunnels? I think I've noticed the software to use a sort of "dead reckoning" to credit you with continuing to move along your previous road at your previous speed for a little while after loss of satellite position fix, but don't know how long that lasts or just how it is implemented, and suspect it is model dependent.

duplicate post

been away...
yes I have both units and like you I have lapsed with my use of the 3790, actually I have two of the 3790's partly because at the time I liked it/used it constantly... but it didn't have the hd traffic updates hence the costly move to a 3597. and at this point I'm not sure the traffic updates are any good or worth the extra investment. At least that's what I feel about the Toronto area.

I don't remember ever having an issue with being shown in the wrong lanes with the 3790. It just seems the newer 3597 has me saying out loud... I am in the express lane!...

the feature is usually helpful; but on elevated ramps, the garmin sometimes picks up (and displays) the street or lanes BELOW.

ouch.

ya I'm seen that too... related to speed limits on the Gardner Expressway... tells me I should be doing 50kmph in some sections... nothing to do with construction or work being done on the roadway.

I have been surprised that my 3597 accurately displays the HOV lanes in Houston (even distinguishing between double and single HOV lanes). I've used the unit since it was released, and I've been pleased with the lane accuracy -- at least in Houston. I haven't used it in other cities.

I have used a 2360 in the highway tunnels of Montreal and Boston and been impressed with its ability to tell me what exit to take while underground. I assume it wasn't receiving because the satellite radio stop receiving.

I have had the same issue on several ocasions down here in Florida. It seems to be only with toll roads. As soon as I said to allow toll roads in the option and also checked allow offroad it seems to go away.

I am using 3597 for the past six months or so in Toronto area. I have seen sometimes when driving with navigation on and directing me to go to 401 east express lanes but I chose to take collectors, it will still continues on express lanes until next romp or so and then corrects itself. Strangely, if I am driving without navigation, then it detects 401 express and collector lanes correctly. Previously, I used nuvi 765, that unit always had this issue or not detecting the correct lanes. Nuvi 3597 is lot better.