Does anybody know the margin for 'hitting' a Via point?

[FrankB]

A lot has been asked/said about Via and Shaping points on this forum. One thing I would like to know has not yet been discussed as far as I know. And that's the margin. Let me explain.

A Via point needs to 'hit'. (is 'visited' a better word?) If you dont, the Zumo will insist that you do, by making a U-Turn for example. My question is how near do you have to get in order for the Zumo to accept?
This applies above all for the starting point of the route. Nothing more annoying than not being able to start the route, because you're not passing the starting point.

- Is it a fixed distance? 10, 50 100 meters?
- Does the speed that you drive matter?
- Does it matter if it is a Via Point on a road, or a POI? (Suppose you put a Via Point on an Airport, that would be difficult to hit)

My guess is that there is a margin, the location that GPS receives also has a margin. Maybe the lat/lon values of the Via Point are rounded to 4 or 5 decimals. But I can not find what this margin is. Thanks in advance.

[Peobody]

I have read that it is 30 feet (9 meters) but I also see varying accuracy numbers reported by the XT, usually 30-40 feet. I don't know whether that 30 feet is in addition to the accuracy number or is based on expected accuracy but I can say that a real-world experience was about 30 feet. This is based on a fuel stop where the pumps were around 80 feet from the convenience store building. When at the pump, the XT did not show me as "arrived", so after fueling I rode towards the store building until it did.

[rbentnail]

Like Peobody, I've been in the vicinity of a via point and not satisfied the XT. Several times in fact. The 595 was the same way, that's why I now put all my route start points down the road in my direction of travel. I've even been in 2 motel parking lots riding around but never made the XT happy. I think it wanted to visit the lobby.

[jfheath]

I believe that once the first announcement has been made that you are approaching a Via Point, then it accepts that you have visited it.

I say 'believe' because I noticed it happen once and subsequently every time I missed a Via Point the behaviour supported this theory. But it hasn't been rigorous testing.

I don't think that it is purely distance related because if you have to make a turn in order to reach a Via Point, it will have to give the turn instruction (being the next thing on its 'to-do' list), before it can say anything about the via point ( eg Approaching....; Arriving at ...)

I never put a Via Point in a location that is off the road. Although the location may appear on the map, the location may not be navigable. If it is not navigable then you're not on the route so that will possibly throw the software a curved ball. Car parks for example - sometimes, eg large motorway service centres - the main route through a car park is navigable, but not the strips of tarmac between the lines of parking bays. I think if you are off route, it will have problems telling you that you are approaching anything.

The Zumos process a list of events and if you are on route it waits until you are within a certain distance before it speaks the next instruction in the list. You can display this list as a sequence of directions on the XT screen. Ive forgotten where that is now.

[FrankB]

Thank you so far for your replies. I will do some testing myself and post the results.

[Peobody]

I never put a Via Point in a location that is off the road.

Don't you use POI's as Via Points? They are almost always off the road. I agree that a Via Point in the middle of a car park is not wise. The same goes for a popular tourist attraction where parking will be a long way away from the visitor center or the coordinates of the POI. Those situations are rare though.

I don't think that it is purely distance related because if you have to make a turn in order to reach a Via Point, it will have to give the turn instruction (being the next thing on its 'to-do' list), before it can say anything about the via point ( eg Approaching....; Arriving at ...)

I don't recall the XT ever giving an instruction to turn into the parking lot of a fuel station, restaurant, or motel but have experienced the XT not detecting that you visited that point. Distance may not be the only factor but I believe it is the primary one.

[jfheath]

There is an odd situation that I came across a few weeks ago. I was following a route and getting no info about Via points as I approached and passed. Just as you describe.

The route had shaping points, and early on in the route, I missed one of these and rejoined the route later on. The route continued navigating ok. - No problems about missing the shaping point.

I pressed the skip button expecting to invite me to offer to let me skip the next point ahead. It didn't. It showed me the point that I had missed a while back. I cancelled that without skipping anything and I continued to follow the route and the sequence of via and shaping points. No alert for the via points was given.

When I got home I checked what it had done. Basically, although I had by-passed the shaping point early in the route and rejoined the route, I expected it to have automatically 'skipped' that point ie removed it from its list. It hadn't. Subsequently it hadn't removed any of the points from its list even though I had passed through all of them. At home, I still hadn't reached the last point (I never plot home as my house, it is always where the Xt thinks the centre of the town is) so the route was still active. I pressed skip a number of times to formally skip each of the route points that I had passed through. None of them had been removed. Eventually I recahed the point before the last point, skipped that and the route seemed to be active again.

This was a bit like going off route with recalc turned off - except the satnav was still giving instructions, but it never recognised the via points as I approached and arrived.

I can't be bothered to investigate this further, but it was different behaviour from what I expected.

Relevance ? Well, maybe if you missed out an earlier shaping point and rejoined the route. It seems to be ok navigating, but mine didn't announce approach and arrival.

[Peobody]

I remember approach and arrival announcements but never an announcement that instructed the turn into the parking lot of a POI.

Your experience with navigation without alerts due to missing a shaping point likely explains the times when I have wondered why I wasn't hearing alerts. I wasn't specifically aware of it but now wonder if it subconsciously contributed my unease about routes that contain shaping points, especially in light of the discussion about visiting points that the XT doesn't recognize as visited.

[rbentnail]

There is an odd situation that I came across a few weeks ago. I was following a route and getting no info about Via points as I approached and passed. Just as you describe.

The route had shaping points, and early on in the route, I missed one of these and rejoined the route later on. The route continued navigating ok. - No problems about missing the shaping point.

I pressed the skip button expecting to invite me to offer to let me skip the next point ahead. It didn't. It showed me the point that I had missed a while back. I cancelled that without skipping anything and I continued to follow the route and the sequence of via and shaping points. No alert for the via points was given.

When I got home I checked what it had done. Basically, although I had by-passed the shaping point early in the route and rejoined the route, I expected it to have automatically 'skipped' that point ie removed it from its list. It hadn't. Subsequently it hadn't removed any of the points from its list even though I had passed through all of them. At home, I still hadn't reached the last point (I never plot home as my house, it is always where the Xt thinks the centre of the town is) so the route was still active. I pressed skip a number of times to formally skip each of the route points that I had passed through. None of them had been removed. Eventually I recahed the point before the last point, skipped that and the route seemed to be active again.

This was a bit like going off route with recalc turned off - except the satnav was still giving instructions, but it never recognised the via points as I approached and arrived.

I can't be bothered to investigate this further, but it was different behaviour from what I expected.

Relevance ? Well, maybe if you missed out an earlier shaping point and rejoined the route. It seems to be ok navigating, but mine didn't announce approach and arrival.

This behavior you describe is what I see often. I typically have via points for start and destination with ALL shaping points in between. For a long time you have been posting about "automatically skipping a shaping point when the route is rejoined" but I rarely see that. Manually skipping one or more shaping points is required.

[jfheath]

Yes, I. remember seeing those comments. I didn't understand fully at the time.
Its odd. I don't think that the 590 used to do this, but it may have done. The route still worked, but it displayed an odd behaviour which I cannot recollect, but it was enough to alert me.

Thanks for the comments.