A comparison between XT and XT2 when trying to provoke RUT behaviour.
I can provoke RUT behaviour in the XT by preparing a route which has just two alternative ways to get from one point to the next. The Zumo calculates one route, I take the other. But first I have to start the route, pass through the start and then Skip a route point to force the Zumo to recalculate the entire route. The sort of situation that I have come across many times when road works, traffic, accidents etc require me to change my plans. So for this test, I put an additional route point half a mile after the start - just so that I can skip it.
Click the images to see a full size version.
Image 1. Just started route. Note that bottom centre there is a green flag and two orange flags. The green flag is my location.
The first orange flag is the start of the route.
The second orange flag is a via point that I intend to Skip.
The only other plotted points on the route are the last orange flag via point and the finish flag.
- XT2 vs XT Routing 01.png (719.14 KiB) Viewed 567 times
Conclusion - Both routes are the same at this point.
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Image 2. 2 miles. I passed through the start point, and I stopped briefly to press the Skip button. This is about half a mile later - I stopped in a lyby after the skipped point to see what had happened to the routes on both devices.
Note that in both cases, the orange via point flags have gone. There is no magenta route behind me. The green flag marks my current position.
Up ahead the route is still heading East (ish) along the A59 before truning north. The orange Via point and chequered flag are both in place.
- XT2 vs XT Routing 02.png (730.3 KiB) Viewed 566 times
Conclusion - Both routes appear to be the the same at this point.
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Image 3. 9:49am. Approaching A59 Roundabout
This is about 3 miles later, approaching the A59 roundabout. Curious that with identical routes and identical maps, on sat nav thinks that the next Via Point is 2 miles further away than the other. Both had recalculated the route after I had pressed Skip. Perhaps one has calculated a slightly different route from the other. If so, I didn't see it - but that remains a question mark - I will take a look at the distances on the simulator.
One of the screen shots is taken slightly later than the other - but that is of no consequence. The significance of the roundabout is that I am not going to follow the instructiosn. I am taking the 2nd exit - the yellow road heading towards Bolton Abbey.
- XT2 vs XT Routing 03.png (515.97 KiB) Viewed 560 times
Conclusion: There is a slight difference in time to be investigated, but I expect both Zumos to compain when I do not take the third exit.
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Image 4. 9:53am Turn Back Loops and U turns.
These are to be expected. The point where it is faster to continue ahead - identified by repeatedly moving the bike's current position and asking it to navigate to the end point - is a few miles further ahead. The XT2 seems to prefer turn-round loops initially, but it later demanded U turns.
The XT - well - - I messed up. I had reset the XT and forgot to check the U turn status - so that too found loop back routes or side roads. Later, I switched the XT to allow U turns. More later. Never mind - this is about the XT2, and what that does when it reaches the tipping point.
Note that the distances to the last Via point are both increasing - because the Zumos are expecting me to go back to the roundabout.
- XT2 vs XT Routing 04.png (458.16 KiB) Viewed 559 times
Conclusion - U turns / loop backs are expected behaviour on this section of the road. Both Zumos are beahving normally.
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Image 5. Approaching the Tipping Point - 5 minutes later - where it is faster to go ahead, than it is to go back.
Half a mile before the junction, the XT2 has already identified that it can take the road I am traveling and get there faster than if it turns me back.
Look at the arrival times shown in the images for the last screens.
At the same point, the XT is still trying to turn me back by using the road on the left.
- XT2 vs XT Routing 05.png (495.5 KiB) Viewed 557 times
Image 6. The Remainder of the XT2 route on the preview map.
Both images are the same location. I zoomed in and took the right hand image because I noticed something different: The position of the green flag. ie the start of the current section of the route - after it had recalculated. Note also that the orange Via point and the end point are still in position. This is exactly what I believe should be happening - at each point, before deamnding a U turn to pick up its last calcaluated section of route to go back - it should calculate the distance or time to the next route point (via or shaping). If it is less than its previous calculation then yes - let's go this way please.
- XT2 vs XT Routing 06.png (806.08 KiB) Viewed 555 times
Image 7. XT Overview Map at the same location.
This is the XT screen, 2.5 miles after the point where the XT2 decided to route ahead.
- XT2 vs XT Routing 07.png (312.98 KiB) Viewed 550 times
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Conclusion: Positive outcome for XT2 - But not yet Proved.
Why? Well - I messed up. I wanted to have U turns disabled on the XT - because the map on the XT reveals all of the turn-around loops that it has created, and when the XT is displaying RUT behaviour - it keeps these turn-around loops as part of its route back.
But early on in the test, I wanted to see if the behaviour was the same as the XT2. So I turned U-turns back on again. This may have casued a recalculation that resulted in that odd milage difference. But later, I needed the turn-around loops to PROVE that the XT was displaying RUT behaviour. Because the roads were so narrow, I couldn't stop the bike (although it kept asking me to perform a U turn !!).
So when I was stopped to get screenshots used in Image 6 and 7, I also took the ones below - just after I had disallowed U turns.
Now thes images are very interesting:
- XT2 vs XT Routing 08.png (490.88 KiB) Viewed 550 times
The left hand image shows that immediately after changing U turns back to disallowed, the route changed. I don't believe that the route recalculates normally, But now, the route was navigating ahead, not back. Just prior to stopping to take this shot, I have a commentary that says it was asking me to perform a U turn at the junction.
So was turning off u-turns the trigger for it doing this ? Is that something that could be used if anyone gets trapped in a RUT ?
I have never seen this before - although disallowing U turns does force the satnav to look further ahead than normal. Maybe as soon as I reached the junction and turned right, the XT would have given in anyway. In which case this whole test is invalid - because in previous RUT tests, the XT hasn't given up until it was less than a mile from rejoining the original route. Starting to navigate ahead just 2.5 miles from the tipping point is not so bad. It certainly isn't what I described as RUT behaviour.
But now look at the right hand image. What has happened to the Via Point flag just before the end flag ? It is no longer there.
Now this, I have seen before. In fact I have a video of it happening. It seems that if you press skip, the entire route is recalculated. If the route is imported, the nature of the route then changes. Subsequently, if you miss an instruction to take you to the next route point, that route point is removed from the route. Having said that - it didn't notice it happening when I was testing RUT behaviour in other locations.
Whatever - none of this happened on the XT2, and on this test the XT2 behaved immaculately.
I'll listen to my in-ride commentary - see if I have missed anything.
Next time I go out, I will run this route again on the XT and get more screen evidence.
