What is the "size" of a via point when recognizing arrival - RV760LMT

Former Member over 11 years ago

Simple route from point A to point B, with a via point stopping at a Flying-J truckstop for fuel.

The via point obviously has a certain reported GPS location in the POI database (which can theoretically differ between GPSs), but what is the "size" of the via point for the RV760 when it comes to recognizing arrival? Theoretically, that "point" should be recognized with a certain margin. Some size circle around the known location.

In my case, since I fuel with the big-rigs, I take the truck entrance, not the standard auto-entrance, and the RV760 never realize that not only did we arrive, but we were had been stopped there for a while.

Another RV-GPS, running in parallel with the same general setup, saw and announced the arrival, and then skipped on to the next stop by itself.

The RV760 spent the next 20 miles yelling at me to circle around and go back to Flying-J, because it did not realize that I had in fact both arrived and stopped. :D
Until I manually went to route review and hit Go for the next stop, it never gave up thinking I should make a U-turn.

Seems via-point arrival would have a certain margin on it, so one does not have do guess it's idea "known location" and drive over that spot in the road? ;)

0 Former Member over 11 years ago

The RV760 spent the next 20 miles yelling at me to circle around and go back to Flying-J, because it did not realize that I had in fact both arrived and stopped. :D

I can't help you in regards to the RV760LMT. What I can say is that my 1490T gives up after a mile or two. and skips the via/waypoint, in similar circumstances. I've seen it do this many times.

There may be a setting for this in the RV760LMT somewhere. Then again perhaps not.

0 Former Member over 11 years ago

Like taking a slow skip through a Wal-Mart or Lowes delivery truck area...

Well I won't admit, in public at least, to ever doing such a thing :D Some times its better to let the GPS beep, or whatever, and use ones brain.

Some times it's better to beg for forgiveness than ask for permission.

0 SUSSAMB over 11 years ago

Seems via-point arrival would have a certain margin on it, so one does not have do guess it's idea "known location" and drive over that spot in the road? ;)

You may want to see if your 760 accepts shaping/do not alert points from Basecamp. If you use those instead of viapoints then you can skip them without any rerouting. Only use via points for those you MUST hit, eg planned lunch stop. All 2013 nuvis work that way so I suspect your 760 should also.

0 Former Member over 11 years ago

Hence, making the GPS actually recognize an "arrival" (or at least knowing how it does it) is still relevant.

I believe it is done by distance. I don't know if that is configurable. I don't think any of my 3 units allow that to be done.

The problem with using Garmin map POI's is that they're frequently "off" and sometimes non-existent. When I create routes I actually use Garmin's POI's (coordinates) to find it in Google Earth, sometimes using street view, and create a waypoint using the actual coordinates. I then include that in my route(s).

Another issue, especially with gas stations (in the US), is that they go out of business often. I don't know how many times I've searched for a gas station in a unit only to find that it is no longer there. In your case you're using truck stops so that is probably less of an issue.

What I do these days is estimate an area in a route, based on my vehicles MPG, where I'll need to fill up. I then search for gas stations, verify they exist, and
create waypoints for them. I also try and find alternatives nearby "just in case".

Of course all that is "work"--more than most are willing to do. In your case it may not even be practical.

0 Former Member over 11 years ago

But fuel stations for major brands (truck stops or not) are permanently tracked by the brand owner.

And it is not usual for me to visit their websites to verify details :)

BTW one can always create Custom POI's. I have a database (geographic locations in my case) that I keep in all 3 of my units.

Garmin's POI Loader

nüvi Custom POI

0 Former Member over 11 years ago

I like to see root-causes fixed instead.

Sure but I deal with things as they are. Garmin POI's are unreliable so I don't rely on them. Of course using Custom POI's and/or doing your own research is a "workaround" but so are many things in life. Using GE is a "workaround" for me and when I did it it was in an unconventional way (in a VM using a clone device etc). Not my ideal solution but it got the job done--albeit with some amount of cursing :)

0 Former Member over 11 years ago

In the very old days one didn't have to actually arrive at the waypoint; instead, as soon as you crossed the bisector of the angle between the course approaching the waypoint and the course leaving the waypoint the device would switch to the next waypoint. There MAY have been a distance circle but I don't think so.

0 danham_ over 11 years ago

...But arriving at a large truck stop, you would (like in this particular case) risk entering through an entrance quite a few feet before the potential cross-point, and when exiting again you go out through a different entrance (back entrance on the truck side), onto a frontage road, and then further down, you re-enter the high-way...

Adding to the problem is Estimated Position Error. If your GPS is not resolving to accuracy of "quite a few feet," it may never know you are in the circle or conversely may believe you are when you are not. On top of that, on-road GPS units are designed to rubber-band to the picture on the screen (the map), which itself is never a 100% perfect representation of the real world. If it did not you would get all kinds off off-route errors. So even with low EPE your actual location and the vehicle icon on the screen may differ by more than the distance between exit ramps in your example.

What is interesting is that different models of GPS, and even different firmware versions on one model, have varying tolerance for when they stop nagging if they think you missed a via. How that works I don't know and doubt Garmin would say.

-dan

0 Killtimer_ over 11 years ago

The other problem you see is an inaccurate address reported by the POI owner. Sometimes the business address is an office location slightly removed from the actual business. I've seen this with large truck stops in the US that include a convince store containing the business office, that is a different address, and quite a bit removed from the pump island.

0 Former Member over 11 years ago

The other problem you see is an inaccurate address reported by the POI owner.

Or the address is accurate (as a postal address) but totally useless for locating what you're looking for. An example of that is malls in the US. Some cover a large area but the POI's are all right on top of each other next to a road.

I once spent about 45 minutes driving around a large outdoor mall area looking for a retailer. In the end I found it on the other side of the interstate (it'd moved) way off the road. As I recall I called them and asked "where are you?".

I've found other establishments tens of miles from where the POI was on the Garmin map. Addresses in rural areas are notoriously inaccurate in the US--at least the ones I've looked for.

As I said before in this thread Google Earth and street view can save you a lot of frustration. It's not 100% but way better, IMO, than driving around.

One day people will publish their coordinates along with their address. Some chains (e.g. Cabela's) already do.