GPX Versions 1.1 vs 1.2 for Garmin Visually Explained

[John S Parry]

@Steve-Jarrell I got out again today to run another test of "Up Ahead", but this time without adding/inserting a via stop into the 1.2 route.

For testing, I created a new 1.2 route to simulate a real situation. When I was few miles from my test deviation, I did the "Up Ahead" thing, selecting the via point to route to. This time, I selected "create a new route" instead of modifying my 1.2 route. I pressed "Go", and my new route started guiding me. I got to the new destination without issue. While stopped, I brought my 1.2 route back up, and it immediately presented the starting point radio box. I selected 'Closest Enry Point", and off I went. Long story short, the remaining route continued exactly as originally planned. Success!

I love it! No skipping waypoints or other stuff you have to deal with on the Next app. I'm now confident I can use 1.2 for just about any situation.

[Steve Jarrell]

@John-S-Parry Awesome!

That makes logical sense (that's not always the case with Garmin) as the 1.2 gpx route has a LOT of gps coordinate pairs in it so when you selected "Nearest Point" it obviously guided you back to one of those points then you were on your way. That's the way that I was hoping that it worked.

Thanks very much for the update!

[Carl Lee]

@steve-jarrell that was a huge typo on my part. It was meant to read “and even if you are not using Tread”. I must have been tired. I’m all Zumo’d out.

[Steve Jarrell]

@Carl-Lee Been there. Done that. Have the t-shirt!

[John S Parry]

@Carl-Lee said:

" I'd like to add something about recalculation. I haven't played with 'Up Ahead' places by inserting them into my route but on a normal deviation from a 1.2 route with recalculation left on, I've found there is a recalculation but it logically puts you back on your intended route - maybe with a u-turn or merging with it a little further along."

This got me thinking about recalculation to get the Zumo to return you to the route. So I had to go out and check.

You're correct that going off route, with recalculation left on, will simply attempt to return you to the route. It does not recalculate the whole route and trash your custom shaping up ahead. I performed conscious off-route deviations at least three separate times, and they all did nothing other than try to return me to the route. A few of the Zumo decisions on returning me were head scratchers, but they worked, and the route continued as normal.

The recalculations that are a NO-NO are actions that modify the route itself. As discussed, that can be through using "Up Ahead" and inserting a new via point as the next stop. Using Search to find a POI and inserting that via point as the next stop is equally disastrous. In short, don't do anything that modifies your route and triggers a recalculation.

From my perspective, using 1.2 GPX files in the Zumo works very well if you understand the behavior.

[Steve Jarrell]

@John-S-Parry "In short, don't do anything that modifies your route and triggers a recalculation."

I think that sums it up perfectly!

I leave auto-recalculation turned off just from habit using so many different versions of the Garmin, and I'd rather just get back on the route by myself, but off-route re-calculation does not seem to trigger the dreaded "ok, you changed the route manually so that gives me (the Garmin) permission to do whatever I want to to your route".

[Carl Lee]

Still some more testing to be done I think. I’m wondering if “shaping” the route on the Zumo just by adding some more shaping points (not vias) will damage it. In reality, this is something I would rarely, if ever, do but it would be nice to know.
When I get chance……

And anyway, even leaving auto recalculation off, if you’re struggling to get back on the route (it happens!), stopping it and restarting with CEP is a fine and still won’t destroy the route.

[Steve Jarrell]

@Carl-Lee Yep, you're right. Restarting the route from any point is FAR better than doing ANYTHING that signals the Garmin that it's ok to change your route as it sees fit.

As far as adding the shaping points goes I really don't know. I've never done that as I've never had the need to do so. For that matter I've never created a route directly on the Garmin either, so for me there are still a lot of unturned stones!

[John S Parry]

@Steve-Jarrell Yes, it seems with a high degree of confidence, that 1.2 off-route recalculation does not seem to trigger a complete recalculation of the route. It's simply a re-calculation to get you back to the route. I don't think there is an overt amount of intelligence within the Zumo. In each case where I intentionally went off-route to trigger auto recalculation, it tried to turn me around back to the off-route spot for route re-entry. Even when there was a shorter re-entry point a little further up. In a way it makes sense, because it wants you hit all points on the route. But it's not always optimal if all you want is to get back to a point on the route as quickly as possible.

To the last observations made by @carl-lee, I don't know for sure if adding shaping points on the Zumo will destroy the route. But my best guess is that it will. I think that playing with the track sections of a 1.2 route, with adding either Shaping points or Vias, will communicate to the Zumo that all bets are off and trigger a total route recalculation.

Why do I say this? It's not 100% apples-to-apples, but when I export the track of a MRA route as a GPX and then import it into Garmin Basecamp, everything is fine after converting the Track to a Route. If at that point I try to make any modifications, either Shaping or Via, I get a BC warning message to the effect that a total recalculation will take place. I'm guessing this logic also applies to 1.2 routes on the Zumo. An example of Garmin being Garmin. It might be an interesting experiment to conduct, but someone else will have to pick up that torch.