Zumo User Forums

Preventing and Avoiding RUT Behaviour

What is RUT Behaviour ? In certain circumstances for routes imported from outside (Basecamp or gpx files) the Zūmo XT seems to get 'stuck in a rut' - repeatedly asking for a U-Turn. See Pic 1

Repeated U-Turns is not a good description of what actually happens - because it still gets stuck in a repeating loop if U-turns are not allowed on the Zumo. In Picture 1, I am traveling from above the top right of the map. My original route was plotted to travel to the red circle and turn left (south-ish) towards the orange Via Point. At some earlier point in the route, I had pressed 'Skip' and the route recalculated. It decided the best way was to not turn left but to carry straight on to meet the A65 and then head south-east to the orange Via Point. No problem there - although the distance is 17 miles and my route is 13 miles, the XT calculates the time for its route to be 1 minute faster - and the XT prefers to head for the main roads. Whatever, at the red circle I turn left anyway. I believed that that after a couple of miles it will be faster to continue ahead than to go back.

The XT disagrees and for the next 12 miles traveling south down towards the orange flag, it repeatedly demands a U-turn to take me back to the red circle - the point where I left its route - and then take the route that it had plotted.
At the place where I took the screen shot for Pic, I am at the green flag - 10 miles after the red circle and 3 miles from the orange flag. To go back from there will be a journey of 27 miles to reach a point just 3 miles away.

Why is it stuck in a rut then ? We might expect (from previous Zumos) that when deviating from a route that the Zumo will recalculate a brand new section of route to the next route point. But in this situation, it doesn't. From the evidence that I have, it first calculates a route back to the closest point of the original route - not to the next route point. That is back at the red circle. If I ignore, it then calculates a way back to the closest point - which is the new bit of route to the red circle. And it keeps doing this - going for the closest point - which is always just behind me.

It isn't completely stuck in an infinite U turn loop, because eventually - when I get closer to the magenta line - it heads for that. So far, in my numerous tests, that distance has been just less than a mile. But just before then it is wanting me to go back 29 miles to meet a route that is just 1 mile ahead of me.

When Does it Happen ? It only happens with imported routes, never on a route created entirely on the XT.
It seemed initially to be initiated when the XT recalculates the route. eg when using 'Skip', but we have indication that this may happens with any imported route.
Subsequently, RUT behaviour happens if I deviate from its route. It seems to want me to return to where I first left the route.

Note that repeated demands for U turn do not by themselves indicate RUT behaviour. But if it continues, when the way ahead is clearly the best way to the next route point, then it seems likely. There are other symptoms that can prove it.
Avoid RUT:

• Do not use 'Skip' or 'Edit Route'.
• Do not allow the route to recalculate.
• Do not deviate from the plotted route !!
• Plan routes on the XT

These avoid the problem - they do not prevent it from happening.

How to Prevent RUT behaviour - (using a PC) Use the solution developed by FrankB and posted at the link here:

www.javawa.nl/triprepair.html

How to Prevent RUT behaviour - (using the XT screen)

• On the XT load the route → Go! , select the start point → Start
• Re-open the trip planner and select the Active Route.
• Save with a new name. This adds the current position as a new start point.
• Load the new route → Go!
• Select the original start point → Go!

If the XT has problems calculating a route that starts hundreds of miles away, then either:

• simulate your bike position closer to the start, OR
• re-save the route the night before when the start point is just outside !

Both of these solutions produce routes that are listed under 'Saved Trips'. It seems that only 'Imported Trips' suffer from the RUT behaviour.

The information on these pages has been acquired from personal experience of using and testing the behaviour of Basecamp and my Zumo XT. I have no links with Garmin, and these pages should not be regarded as instructions. They are presented for interest only. The contents of these pages must not be shared, copied, transmitted, redistributed or re-published in any form without my permission. (C) JHeath 2021.