Latest Contributions by JaySandhu

You can have more control on where a location is snapped by adding some logic to the snapping. See the section titled "Snapping environment with Build Query" here: What are network analysis objects?—Help | ArcGIS for Desktop Also you can calculate one of the Attr_ fields on the input stops for additional cost to be added to the route. The Attr_ field should correspond to the cost attribute your are solving on and in the same units. You can read more on them in the Stop Properties section here: Route analysis—Help | ArcGIS for Desktop Jay ... View more

Can you explain how you want to apply this 100 mile cutoff when traveling from point 1 to 2 to 3, etc? It is not clear what the route solver should do in this case. Jay ... View more

What solver are you trying to use? For example the route solver will find a path between the stops you load in. It is not going to constrain itself to a length limit. But Closest Facility does have such a cutoff. With that solver, you can use it solve for all (or some) facilities within a cutoff of 100 miles. Jay Sandhu ... View more

The maximize capacitated coverage requires you to enter the number of facilities to solve for. To find the minimum number, you have to do what you already figured out. If you are going to automate this via a script then do consider using a binary search and not reduce by 1 as it will be more efficient to find the minimum number of facilities needed. Another thing to keep in mind that a demand location can only be assigned to one facility. It's demand cannot be split between two facilities. So if you have the situation where the demand values are large and no one facility has the capacity to serve it, you could place more demand points at the same location with less demand. So a location with 20 demand units could be replaced by 4 points with 5 demand units each. ... View more

Network Analyst solves routes using the network dataset. The network dataset provides the cost attribute that it minimizes on and a set of restrictions that can turn on/off places that can be traveled on, You can also import or set up temporary barriers. That said, the cost attribute can be made from a combination of factors/fields in the input data. But in the end, there is only one cost attribute you can pick at a time. The route solver will not try to minimize more than one cost. So if you can combine the multiple fields into one cost then yes Network Analyst to solve on it. And you can add multiple cost attributes to a network dataset from different fields and pick any one of them to solve on. As far as selections, what role are are they playing? Do you have a set of points to visit and you make a selection to visit a subset? If that is the case, when you Load or Add Locations to the stops, it does honor selections. The Load Locations has a check box for "Only load selected rows" and it will be Checked on by default if you have a selection but you can un-check it. If you are trying to select edges to "restrict" the travel to, then you will have to use the restriction model as I mentioned above to model these selections. ... View more

Good discussion here. I just want to add that the network analyst tools like the route solver can help "reorder" a set of roads using the Find Best Order option. So if your street data is topologically connected, then you could build a network dataset on top of it. Make a route analysis layer, select all the roads with same name, say, main street, and then select all the end points, hint: nodes (or create mid-points using the Feature to Point tool) and load them as stops and solve with Find Best Order option. This will create a new route and each of the input points will have a sequence number in order that you can use for the order. So you could automate this process for each unique road name in your data and as Richard alluded to in one of his posts, you can get 80% work done this way and rest manually. The linear referencing (dynamic segmentation) approach to constructing a "Route" needs a name to group the streets and then some fields with measure values to order the streets into that route. And I think that is what you are missing, the measures. So you can not use the dynamic segmentation to geo-spatially order your data.  Another tool that may help you in your efforts is a GP tool called SORT that can reorder your rows based on an input sequence. Network Analyst has a tool called DissolveNetwork that merges adjacent roads if it can (to reduce the number of edge) and spatially sorts them on disk to make it more efficient to retrieve (for faster route solves). ... View more

A solution to optimally visit ALL edges in a network falls under a class of problems called arc routing, also known as Chinese Postman or an Euler tour. Network Analyst does not provide a solution for that class of problems. BUT it can provide a solution to best visit a set of points, also called a travelling salesman problem (TSP). So you could place a point on edge and optimize it. But there are many caveats to using a TSP solution for all edges in a city. How big is the town? How many road segments does it have? How much miles does your friend want to run at a time? You will likely have to partition the town into smaller regions and solve these separately. An easy way to place a point on every edge is to use the GP tool Feature To Point and checking the "inside" option. This will place a point at the center of each line. Then you can use Network Analyst solver Location-Allocation to "partition" these points into clusters of say 300 points (maximize capacitated coverage problem type in location-allocation). Then you can load these sets of 300 points into the Route solver and choose the Reorder stops to find optimal route option. Couple of things you can do to improve the solution is to set the curb approach property of all the points you load in as Stops with No U-Turn. and set u-turns at dead ends only. You can also turn off restrictions as one-way as a runner can disregard that! Hope this gives you enough information to set up a running route! More info on Route and Location-Allocation here: Route analysis—Help | ArcGIS for Desktop Location-allocation analysis—Help | ArcGIS for Desktop ... View more

Pranav, It is hard to say what is going on without looking at the data. Is it something you can zip and email to [email protected]<mailto:[email protected]> then j can take a look to see what is going wrong. Jay Sandhu Sent from my iPhone ... View more

As the error message implies, there is an invalid value in the input data. Perhaps there are some values out of range or not the right type (string instead of numeric or decimal values for an integer type) for some weight attribute. Most likely the string/number might be the culprit. So check the field definitions of fields that supply the data for the weight attributes in the network dataset. Jay Sandhu ... View more

Hello Pranav, Have you looked at the help: Historical traffic—Help | ArcGIS for Desktop Specifically, the steps are here: Configuring traffic data in a network dataset—Help | ArcGIS for Desktop Also, there are two tutorials, number 1 and 10 that show how to configure this type of data.These are here: About the ArcGIS Network Analyst extension tutorial—Help | ArcGIS for Desktop Where exactly do you run into problems? Please add some more details so we can help you find a solution. Regards, Jay Sandhu ... View more

The algorithms used by Network Analyst are described here: Algorithms used by the ArcGIS Network Analyst extension—Help | ArcGIS for Desktop As discussed there, for Location-Allocation, we use a vertex substitution heuristic to solve the p-median problem. And we use a process called Hillsman editing to first transform a particular problem type such as Maximize Coverage to a P-median and then use the same heuristic. Here is a reference to the original paper by Ed Hillsman: Hillsman, E.L. (1984). The p-median structure as a unified linear model for location-allocation analysis. Environment and Planning A, 16 (3), 305-318 And here is another researcher using a similar approach: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.26.4638&rep=rep1&type=pdf Regards, Jay Sandhu ... View more

I think the first question to ask/answer is what should additional resources at a fire station do? Does it increase its ability to reach further? Or does it ensure that more services are available to the same population so that you can tally who does and does NOT have this service available? Without a goal it is hard to say what/how to use Location-Allocation in this case. Jay Sandhu ... View more

I did not understand what you mean by service area validated the impedance but LA did not have similar effect. Service area grows uniformly outwards and the polygons are an approximation to cover all the roads traversed from the starting location. Jay ... View more

You may also want to look up work that Mike Price does in this area of fire/emergency response. E.g., http://www.esri.com/library/ebooks/fire-mapping.pdf Jay Sandhu ... View more

Definitely ask more that is not clear! As I said before, you can generate many alternatives. e.g. what if I have the budget to move only two? Which two? What If I only want to cover 95% of the population in 3 minutes, how many fire stations do I need? Hint: use market share. So get comfortable with using LA and looking at it's results. You may or may not want to use Closest Facility with 1 closest, you could look at 2 closest and pick the better one... Jay Sandhu ... View more