Here’s a brief synopsis of what I am running into with Network Analyst- the goal is to create service areas for fire stations based on travel times.
I have a baseline county wide roads shapefile that I have used as input to successfully create a network dataset and create subsequent service areas based on travel times.
Next, I add new roads (i.e. digitize by hand) to the baseline roads dataset for a part of the county where a new housing development is going in. I am then able to create/build a network dataset without any hitches. However, when I try to create a new service area using the updated network dataset created with the updated roads shapefile, the new roads that I have added are not included/taken into account in the service area polygons that are generated.
In short, my goal is to be able to add new roads to an existing roads shapefile and have those roads included when network analyst solves for my service area query.
PS- I have run the Integrate tool on the shapefile with the new roads and I still receive the same results - the new roads are not incorporated in the service area polygons that are produced.
Any help that anyone can provide to help solve this problem would be greatly appreciated .
First, make sure your new roads are actually snapped to the existing roads. If there is even a tiny gap, they will not be connected in the network.
Next, check your network's connectivity policy. If the connectivity for your streets is "End Point", then the new streets must snap to end points of the existing streets in order for them to connect (and the Integrate tool won't help here). If you want your new street to be connected in the middle of an existing street, then you need to split the existing street, and also be careful to fix any attributes in that existing street feature that might have gotten messed up due to the split.
If your connectivity policy is Any Vertex, then then streets don't have to touch at end points, but there does need to be a vertex on the existing street at the location where the new street touches it. However, the Integrate tool should have taken care of this, so I suspect that the problem is one of the others I mentioned above.
Thanks Melinda for the reply and pointing me in the right direction. When adding new roads to the baseline dataset, the key was creating the new roads and connecting them non only to one another at endpoints but also the original roads features at endpoints as well. Splitting existing roads into new lines with respective new endpoints was also key.
One additional note was that there was not an option when building the network dataset to use vertices; the only option was endpoints.
Thanks again for your great help - it led to the right solution.