Latest Contributions by DougSterling

I get why i need to chose 'Minimize Facilities' (to result in the lowest number of detectors possible to cover an area), but I'm seeing results where 2 neighbouring 'candidates' are getting chosen, despite being less than 250ft apart. Why is this? It may be that that your water/wastewater network is disconnected and you cannot actually reach the meters that seem to be within 250 meters.  Try to load two meters (which are both facilities and demand points in your location-allocation problem) in to a route layer, set the route impedance attribute to be your length field and solve the route.  If no route shape is generated then the edges are not connected.  If a route shape is generated then look at the field for the route distance and make sure it is less than your 250 meter cutoff. You can probably resolve any connectivity when creating network datasets from geometric networks by: 1. Running the integrate tool ( http://resources.arcgis.com/en/help/main/10.1/index.html#//00170000002s000000 ).  This tool will make sure that all features that are coincident within a tolerance you provide are made to be exactly coincident.  If two water lines cross then a common vertex will be added to both of them which will enable connectivity in the network dataset. 2. Changing your network dataset connectivity policy (found on the Connectivity tab of the network dataset properties in Catalog) from "End Point" to "Any Vertex".  This is needed if your geometric network had complex edges because complex edges allow mid-span connectivity but the network dataset connectivity policy of "End Point" only allows for connections at the beginning and end of an edge. ( for more on network dataset connectivity see this: http://resources.arcgis.com/en/help/main/10.1/index.html#/Understanding_connectivity/004700000009000000/ ) 3. Rebuild you network (using either GP or the build button on the network analyst toolbar). The problem that you are trying to solve should work just fine so there is probably a data problem that need resolving. Doug ... View more

I'm assuming that the inconsistent polygons are coming from the facilities that only traverse one edge.  It is quite likely that the edges that the facilities are located on are disconnected from the nearby edges.  If your network dataset has end point connectivity then the edge end points must be identical for there to be connectivity.  You can test this by attempting to make a route from one of the inconsistent facility locations to a good facility location.  If there is no route then things aren't connected. Hope this helps! Doug ... View more

I am trying to identify the minimum number of stations using the Location-Allocation minimize stations function.  I have 710 potential locations and roughly 40,000 demand points.  Based on the street speed limits, and the size of the area, I believe that all of the demand points could be reached by 7-9 stations within 4 minutes, and 4-5 stations in 8 minutes (just eyeballing it based on previous service area maps).  However, when I run the minimize facilities problem type using a 4 minute impedance in the location allocation tool, the results show approximately 21 stations, and many are within a thousand feet of each other.  There are only two settings: the impedance cut-off  (I'm using 4) and the impedance transformation (I'm using linear), am I doing this incorrectly?  Any advice would be much appreciated, I've been working on this for a couple of days with much aggravation. You may have a disconnected network meaning that edges are not connected even though they look connected when you draw the network.  Can you route between the chosen facilities that are next to each other? You may have a combination of restrictions that result in a disconnected network.  Try resolving without any restrictions. If you are using hierarchy then you may have incorrect hierarchy values.  Try solving without hierarchy. Your impedance cutoff of 4 may not be what you are expecting.  The impedance cutoff has the same units as the impedance attribute.  Make sure a value of 4 makes sense in light of your impedance attribute (which I assume is in minutes). You may have accidentally added your stations to your network dataset as a junction source and your points are locating on them but they are disconnected from all edges in the graph.  Make sure that when you are locating your stations that you are locating only on your edges, not junctions. Hope this helps.  The location-allocation solver should work in the way that you expect. Doug ... View more

To make the problem reproducible, I have managed to interesect my data set even more to make it small and still have the problem I described. The geodatabase attached with this message contains the edges and the built network. If you look at the junction located at (-73.601234  45.528790), it should not be there if as I understand it the 'end point' connectivity policy means that junctions should only be created where edges meet at their ends. Thanks, Guillaume The problem is that your street data consists of multipart geometries.  The network dataset build algorithm handles multi part geometries by placing system junctions at the beginning and end of each part.  Elevation fields only apply to the beginning and end of the entire multipart geometry, not to the beginning and end of individual parts (which are internally given a Z elevation value of null).  The connectivity you see is correct in light of the multipart shape data in your dataset. You can run multipart to single part GP tool to convert your shapes into single parts but this tool will not preserve your cost values (the cost of the output shape will be a duplicate of the first part in the original shape). I hope that this clears up the behavior you are seeing. Doug ... View more

Hi Jay, I have just discovered the network dissolve function and I have managed to run it fine. However I have some questions. My original network has as its source an edge feature set (call it EFS) which had some custom fields such as the name of my roads. The output of the dissolve network produced a copy of that feature set but with some of the original fields missing including the name of my roads. Now how do I bring back the new network (the output of the DN) to the location of my old network without losing any information? I would like the new network to be linked to the unaltered EFS and not to the incomplete version. I hope I am explaining my problem clearly. Thanks, Guillaume Dissolve Network merges coincident features and updates street field values whenever possible so long as the attributes can be correctly merged and the network topology is correct.  Fields that do not participate in the network dataset cannot be transferred to the dissolved feature class because the dissolve tool does not know how to maintain them. Fortunately dissolve will correctly merge and maintain your road names if the network dataset uses them to generate directions.  You can read about adding directions to your network dataset here: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00470000000q000000 All fields that are used to generate directions will be preserved during the dissolve process.  All fields that are used in directions, attributes, elevation fields, etc are preserved during the dissolve process. Doug ... View more

This functionality is implemented in 10.1 prerelease.  You can contact Esri to enroll in the prerelease program. We have added a new field to the Facilities feature class called "Capacity" and provided a new problem type called "Maximize Capacitated Covering" that uses the capacity field to limit the amount of demand weight that can be allocated to a facility.  We also support a default capacity for all facilities that did not specify their capacity (as well as supporting varying facility capacities and varying demand weights).  The new problem type first seeks to maximize the sum of demand weight that is allocated to facilities and then attempts to minimize the sum of weighted distance for all allocated demand points to the solution facilities. Here's a screenshot of the location-allocation property page with the new problem type. [ATTACH=CONFIG]11337[/ATTACH] ... View more

It isn't a serious problem.  You have requested a route shape with measure information and the solver is unable to provide measures because you have junctions with non zero impedance attributes, turns with non zero impedance attributes or scaled cost barriers. If you open the route layer, activate the "Analysis Settings" tab, and change the Output Shape Type from "True shape with measures" to "true shape" then you will not get this error. The solver is telling you that you asked for measures on your output shape but that it was unable to set measures.  This in no way impacts the route chosen. Hope this clears things up! ... View more

At 10.1 (now in beta) flags and barriers are saved in the mxd with the utility network toolbar. ... View more

Paris has quite a few one way roads and the Paris tutorial data reflects this.  The service area solver only goes one way on a street because the oneway restriction attribute is honored by default.  To change this: Right click on the "Service Area" layer in the table of contents Select "Properties" (on the bottom of the list of commands) Click on the Analysis Settings tab for the service area layer properties Uncheck the Oneway restriction (this will allow you to traverse the wrong way down a oneway street) ... View more

One possibility is to: Take your green space polygon and buffer it by say 10 meters Intersect the buffered polygon with your streets to find the streets that intersect the buffer Use the "Feature Vertices To Points" GP tool to turn the intersected street features in to individual points Create a new closest facility layer (which by default goes from incidents to facilities) Load the vertices as your facilities Load your buildings as incidents Solve to find the nearest park for each building (incident) Hope this helps. ... View more

I've uploaded my shapefiles and analysis dataset to here if someone wants to check out. The source of data is openstreetmap. I downloaded your data and was able to build a Network dataset with the data.  There are three issues to be aware of: 1.  OSM data establishes connectivity between streets by looking for coincident vertexes.  This is not the default connectivity policy for the Network Datasets but this connectivity policy can be changed.  In ArcCatalog you can right click on your already built Haiti network dataset, select properties, enable the Connectivity tab of the Network Dataset properties and change the Connectivity policy for your roads_cut source from "End Point" to "Any Vertex". 2. The FT_Meters and TF_Meters fields have been incorrectly calculated.  The field values seem to be too small by a factor of ten thousand (10000).  You can simply use the Calculate Field GP tool to multiply the current values by 10000 to make them correct (unless there is some reason to leave them as they are). 3. I am unclear on exactly how OSM data intends the oneway field to be used but it seems clear that a field value of "1" means a road can be traversed only in the digitized direction.  The default oneway attribute that is generated by the Network Dataset wizard will be incorrect.  To fix this you need to: Bring up the Network Dataset properties Go to the Attributes tab Click on the Oneway attribute to select it Click on the Evaluators button on the right of the dialog Click on the From-To evaluator Click on the Evaluator Properties button to the right (the button with the hand on it) Once you click on the Evaluator Properties button a dialog will appear and you should set the "Value = " portion of the dialog to simply say "false" Click Ok to close the dialog You will need to rebuild your Network Dataset after you make these changes.  You can do this through the build Network Dataset GP tool or by adding the Network Dataset to ArcMap, enabling the Network Analyst toolbar and pressing the Build Network Dataset button on the toolbar. Hope this helps. ... View more

Or can I work using the SDC Network Dataset provided by ESRI plua a separate File Geodatabase with my Feature Dataset/Classes in it? You can use the SDC network dataset with point inputs from a file geodatabase (or SDE database or shapefile or personal geodatabase).  There is no requirement that everything be in the same workspace or even that everything have the same projection.  It should "just work". ... View more