Closest entry point - again

[Peobody]

One final question on this. Is it best to have uturns turned on?

I don't know whether it is "best", but mine is on. I want to know if my XT thinks I need to u-turn so I can determine why and create my own plan of action. My recalculate is set to prompt, which I almost always answer "No" to, but it's one because I want to know when my XT thinks it should recalculate.

I believe that determining what is "best" has a basis in map reading comfort. Some folks can't read a map so are reliant on their satnav. For others the satnav is just a tool that conveniently provides a map. I go off route frequently but I avoid recalculation, opting instead to manually navigate back to route. Manual navigation is something I am comfortable with. When I miss a turn, I answer No to the recalculate prompt and then I look ahead on the map for the best way back to the route. A u-turn is my last resort.

[smfollen]

I apologize to you and the others for seeming to be so dense on this. As I said in my initial post, I thought that I had this all figured out.

The zumos are complex and they have their quirks. We are all still learning. If it was easy, this forum probably would not exist.

... I have been able to avoid using CEP altogether.

I use CEP to start almost every planned ride, usually with good results, but on occasion, it does something strange, and I learn something new. After starting CEP, I take a look at the resulting overall route before starting off (Settings -> Driver Assistance -> Route Preview), to make sure it makes sense.

As @Peobody suggests, sprinkling in a few via points is good practice so you always have an option if things go wrong.

I am still left, though, with why the Zumo would not follow the route. I was on the magenta line when I selected closed entry point. I understand that it did not know what direction I was heading in. So, it seems that it selected a point that was behind me - presumably also on the magenta line. If I am correct so far, why would it not simply pick up the next shaping point on the line when I started moving. I thought the value of shaping points was that I did not need to pass through them and that when I did not, the Zumo would continue to guide me on the route ahead of me.

You touch on multiple things here.
I have no way to know what specifically happened in your case here but I can offer some thoughts.
First, as I @jfheath and I said above, CEP tries to go to the closest point on the magenta line, not the closest shaping (or via) point. That makes sense. It is trying to get you onto the route as soon as possible.

Were you on a divided highway? GPS is impressively accurate but not perfect. It can get your position wrong by several meters, especially if you are stationary. This is even more true when the GPS receiver first starts up. It can get a "fix" with 3 satellites I believe but becomes more accurate as it acquires more satellite signals, which can take a few minutes. My point here is this - Is it possible that zumo "thought" you were on the opposite side of a divided highway so that you had to go to an exit / entry ramp to get turned around?

Is there any chance your route included a point on the wrong side of a divided highway, a point at an intersection, a point off the road?

I believe @jfheath has previously posted about CEP being confused if it is started while already on the route. I have not had issues in the case, but again CEP does seem to do strange things on rare occasion.

Yes via points must be skipped explicitly while shaping points can be skipped automatically (There is Settings -> Map Display -> Skip Next Stop Confirmation), but that does not affect the selection of the closest entry point. It only applies once you begin to navigate a route. Any part of the original route prior to the selected closest entry point is ignored.

So, I guess a better question is, if you were sitting at shaping point 10989 and wanted to head toward shaping point 956, what would you tell Zumo, keeping in mind that the only starting point options I was given were two that were very close to the starting point and CEP?

I would have done exactly what you did at that point. CEP was your only option, other than selecting the via point at the end of the route, which would not have helped in this case.
For future planning, options include:
- sprinkling in via points
- checking the planned route carefully at close zoom level to make sure all points are on the road, on the proper side of a divided highway and not at an intersection. Also be sure your route does not involve u-turns (e.g a point on a dead-end street).
- breaking a loop route into two parts, out and back
- keeping the zumo turned on, even when not following a route.

One final question on this. Is it best to have u-turns turned on?

I typically do allow u-turns. Without them, the zumo can route you a long way to get turned around if there are no nearby roads that could loop you around. As far as I know, allowing u-turns does not affect CEP's selecting of the closest entry point; it only has affect if you are already navigating a route and go off route. (U-turns can affect RUT I think, but that is another subject entirely.)

[gwilki]

Were you on a divided highway? GPS is impressively accurate but not perfect. It can get your position wrong by several meters, especially if you are stationary. This is even more true when the GPS receiver first starts up. It can get a "fix" with 3 satellites I believe but becomes more accurate as it acquires more satellite signals, which can take a few minutes. My point here is this - Is it possible that zumo "thought" you were on the opposite side of a divided highway so that you had to go to an exit / entry ramp to get turned around?

No, I was on a 2-lane highway.

You both has given me a lot to consider. I plan to do that and keep trying. Thanks much.

[Peobody]

For future planning, options include:
- sprinkling in via points
- checking the planned route carefully at close zoom level to make sure all points are on the road, on the proper side of a divided highway and not at an intersection. Also be sure your route does not involve u-turns (e.g a point on a dead-end street).
- breaking a loop route into two parts, out and back
- keeping the zumo turned on, even when not following a route.

A few comments/observations about this:
1. On the XT, if I use it to shape a route, it will place the shaping point at the closest intersection. I use to avoid placing route points at intersections but this behaviour changed my mind. I no longer worry about it for shaping points but I still avoid placing Via points at intersections.
2. I don't break my loop routes into two parts because I believe the problems inherent with that are nullified by having at least one Via point in the route. Figure eight routes create an additional challenge for CEP. Via points to select as entry points will eliminate that challenge.
3. Keeping the zumo turned on applies to stops during the riding of a route. Leave it on and let it go into standby mode. When it awakes, it is ready to continue navigating from where you stopped.

[proofresistant]

To be honest, I can't follow all the previous answers, even though they are all correct in principle.
We recently discovered the hard way that there can be shaping points that can destroy the entire planned route in conjunction with CEP.
Looking for the best start option to begin a planned route.

It makes it seem virtually impossible, or at least impractical, for the average user to identify such shaping points in advance or to avoid them with certainty.

I still believe that you can plan routes in advance in the same way you are used to doing.
The tip, for example, to use intersections for waypoints is highly controversial.
But the tip to split one round trip route in 2 Routes is pretty indisputable.

How ever, I, for example, use shaping points to shape the route and use VIA points when I really want to stop there. This means that I often only have the start, (n) shaping points, and an end point in my route. That Way basically a good thing.

But what should you do if the CEP problem occurs during your tour?

• Open / Select the planned route in the zumo XT2.

• You will see your position and the next shaping points.

• Take the first suspect is coming Shaping point you see (and may one or two more that follow) and make it/them to a VIA point.

• Done! With all the knowledge you've gained from past experience, that's really all you need to do.
  CEP will now, presumably, work as desired.

Try it!

[jfheath]

A couple of points arising from the above.

The info that @Peobody @smfollen and @proofresistant is excellent.
It doesn't need me to chime in as well. But I will clarify a few things.

CEP is normally excellent. But if it gives you odd results, just start moving in the direction you think you should be going, and try again.
CEP normally works by intersecting the magenta line so if you are already on it, you may get issues.
Do not switch from allowing U turns to disabling them - it recalculates the entire route.
If you allow U Turns, then it will not keep re-issuing them. After 2 or 3 the XT2 starts to look ahead and tries to use side roads to get you to go back. I think this was Garmin's attempt to solve the RUT issue. It doesn't, but it does look further ahead.