I am using VRP to route trash trucks to houses and I am trying to eliminate U turns except at dead ends. When I initially ran the analysis, it followed the no U turn rule correctly, but now it's randomly turning just before intersections and mid-block. I'm using the same network dataset, so I would have thought that it would have encountered any issues in the first run.
The first time through, I ran 4 routes to ~600 locations (I combined pick up points to stay within the limits of the VRP). I used seed points to make sure that each route maintained a general geographic area. Once I was able to get 4 routes that I was happy with geographically, I found that some of the routing decisions made within the route were odd. It obeyed the "no U-turns except at dead ends" rule perfectly.
I then chose to extract all the addresses identified in the previous run through for each route (just over 700 points) and ran a new VRP with just one route in hopes that I could eliminate some of the oddities I found in the original routing. The route found includes U turns at various points that seem to have no rhyme or reason. Many of them actually take place mid network segment - attached is a snapshot showing this.
Any insight into this problem would be greatly appreciated!
Your first method of the combined points is the preferred method for the solver, when trying to do such high densities. The VRP solver isn't designed for the high density problem and even with the combined points it is still a pretty high density problem which is likely why you are seeing some of the oddities. Can you elaborate a bit on what you noticed in the first solve that is a problem with the solution?
As for your second solve. It looks like the routes are turning around at customer locations. Try setting the curb approach for the orders to either "Right side of Vehicle" or "Left side of Vehicle" depending on what side of the street you need to approach the customer. The vehicle should then arrive and depart with the customer on the specified side of the vehicle. If it is set to "Either side of Vehicle" it will allow for u-turns at that location.
The first solve seemed to double back on itself excessively. I'm sure part of this can be attributed to the point density that was used. We are also trying to minimize left turns, so it seemed that starting with a route that wasn't doubling back quite as much would be an easier manual fix.
I double checked the settings on the second solve and even with the curb approach set to "Right side of vehicle", I'm still getting the u-turn locations.
I'm not sure why you are seeing the u-turns in the middle of the street segments with both the u-turn policy set to only at dead ends and the curb approach set to Right side of vehicle. I would recommend contacting Tech Support.