I have created several snow plowing routes using waypoints and shaping points that work quite well except for a minor issue. Generally when I want the route to make a U-turn at an intersection, all I need to do is place a shaping point in the middle of an intersection. About 80% of the time the route will say make a U-turn and the other 20% it will say make hard right or hard left. The hard right/left is also an issue when I want the route to make a U-turn at a dead end. Is there a way to force a U-turn prompt so it appears 100% of the time?
I'm afraid you'll probably have to live with it. If I were to guess, it would be that the road data contains a width value and if one of the roads is considered too narrow for a u-turn it won't allow it; even though an intersection provides additional room to make the maneuver.
Isn't the U-turn announcement supposed to kick in only after the device decides that the driver has drifted off course and/or overshot a destination? If the device is just following a predetermined route point by point near the middle of the road with a good gps signal the routing algorithm would have no reason to recalculate and announce a U-turn suggestion.
But do consider naming all appropriate waypoints with the text to speech label "U-Turn". (Basecamp should increment appended number suffixes). These waypoints could be inserted into the route as a final tune-up (along with removal of unnamed points) if necessary.
39_Steps - The U-turn will kick in if you put one point before an intersection, a point in an intersection (at least most of them), and a point near the first point representing the opposite direction of travel. It's easy to do and usually not an issue. Like I said before it only seems to have an issue at dead ends, angled streets and streets that have multiple names (street has one name on one side and another name on the other side), but even then not all the time. Sometimes I am able to get a U-turn in instances described. That is what makes this so frustrating.
As you will recall, you originally elected to route by shortest time instead of shortest distance. Depending on road vector categories traversed or intersected, the routing algorithm may need to calculate in nanoseconds, but may only have millisecond or decimal second precision. I do not know that answer to that. If your U-turns are at an intersection with a "higher speed" road classification, results may vary more than they would if you used the available shortest distance calculations. There may be other issues of point placement involved, but do try setting the device to calculate by shortest distance instead of fastest time for test purposes. Good luck..
