Latest Contributions by JaySandhu

Right-click on the Feature dataset to get the New menu for choosing network dataset. Take a look at the screen shots at the following Tutorial if in doubt: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Exercise_2_Creating_a_multimodal_network_dataset/00470000005v000000/ Jay Sandhu ... View more

Check if you have a spatial index on your street feature class on which you are loading the locations. Jay Sandhu ... View more

CF is the Closest Facility solver and OD is the Origin Destination Matrix solver. They are very simillar. The difference is that the CF will also return the geometry of the shortest path in addition to the network distances. OD only returns the network distances. That way OD can run faster on large data as it has to do less work on book keeping the resulting shortest paths. You can read about them more at: Closest Facility: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Closest_facility_analysis/00470000004n000000/ Origin-Destination Cost Matrix: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/OD_cost_matrix_analysis/00470000004r000000/ Regards, Jay Sandhu ... View more

Barry, You need two things: 1. You need a road network on which to compute the network distancea and 2. You need locations from where to compute the distances. Looks like you have 2. You can start with addresses, geocode them and turn them into a feature class. You do not need to build them into a network dataset, etc. So what you need is 1. a network dataset. A free one comes with ArcGIS. It is called StreetMap and you may have to install it from your data and maps dvd/cd Once you have that, add the streets to ArcMap, turn on the NA extension and add the NA toolbar. Add your locations (feature class) to ArcMap, Create a CF or OD layer from the NA toolbar and use that to comptue the one to many routes or distances as needed. Jay Sandhu ... View more

Are you specifing start/end time on stops? According to help at: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Time_windows/004700000054000000/ "A route solver attempts to find the least-cost route through a series of stops while respecting chosen restrictions on the network and honoring all time windows. If time window violations are inevitable, the solver attempts to minimize the total violation time." So the objective of the route solver changes and you may get different paths. OR are you setting a start time for the route to start at and your network dataset supports historical time information and that will be used to solve the route and the impedances may be different from the default travel times and result in different paths. Jay Sandhu ... View more

ArcGIS 10 supports 3D networks. You need to have Z coordinates in addition to x,y on your line data. You can read more about it here: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00470000005q000000.htm It also has location of the 3D sample network included with the Network Analyst tutorial. Regards, Jay Sandhu ... View more

As Alan pointed out: "If you want to manage both the lines and points in your network, you should model this in a network dataset stored in a geodatabase feature dataset." So you need to create a Feature Dataset inside you geodatabase and then put the streets, etc feature classes inside the feature dataset and then you can create a network dataset on them. Jay Sandhu ... View more

>Our current position is that we are in no position to improve on the drive times estimated by >Network Analyst and StreetMap Premium. The Streetmap product does have attribute parameters that will allow you to slow down or speed up categories of roads. So when you create an OD layer, you can bring up the properties of the layer and on the Attribute Parameters tab change the speed associated with the roads. For example if you think that 55 MPH are really going at 50, then change it to 50. I know this is very coarse compared to the historic traffic data speed profiles but it does allow some capabilities. If you move to 10, you can use the new scaled cost barriers (point, line and polygon) to change the travel times. For example if you have climate polygons that say where icy conditions impact the roads, you can bring in those polygons and scale them by say 30 percent to slow all traffic down in that region. Simillar stuff can be done with population density polygons. Generally speaking, one of the use case for this new functionality is to import weather conditions from a weather service and slow down things to provide some real time travel times. Regards, Jay Sandhu ... View more

1. make sure you do the same in ArcMap as you did in ArcCatalog to enable the extension: 1. Start ArcCatalog by clicking Start > All Programs > ArcGIS > ArcCatalog 10. 2. Click Customize > Extensions 3. Check Network Analyst 4. Click Close 2. make sure to add a network dataset to ArcMap to enable the solvers such as the Closest Facility. The will remain grayed out until you add a networkd dataset. Jay Sandhu ... View more

Priyanka, U-Turns at three way junctions are rare and can happen when there are one-way streets, and side of street/curb approach set to right or left side. So can you choose the U-Turns Not Allowed option and re-route? If that is not a possibility then you will have a edit the network dataset and add a turn restriction at that location. For using truck height restrictions, you will have to add a parameterized evaluator that you can set at solve time with the truck height and then that is evaluated at run time to restrict portions of the network based on the height. You can read more on that here: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Using_parameters_with_network_attributes/00470000000s000000/ Regards, Jay Sandhu ... View more

This is network analyst forum so you may not get enough response as you are trying to do spatial analysis with euclidean distances. But you may look at the GP tool called PointDistance that will compute euclidean distances between two sets of points with a specified search distance. I would suggest that you compute the distances between your ambulances and service points within some response distance, say 3 miles and then sum up the distances per ambulance site. Now you can rank them from low to high. Sites with lowest sum have the maximum accessability to service sites. Regards, Jay Sandhu ... View more

The OD Cost Matrix solver only returns the network shortest path distance. it does not compute the distance from the unsnapped location of the input point to the snapped location on the network. You can compute that distance by using the GP tool Calculate Locations. This will add the network location fields on to your input origin locations and one of these fields is "distance" and that will be the euclidean distance from the origin to the snapped location on the network. You can then use these location fields to load locations into your origin and destinations. But before you do that, you can create the OD Cost Matrix Layer, bring up the attributes of the origins and add a field called EucDistance. And then load locations and on that dialog, in the field mappning of properties, map the EucDistance to distance field. Now when you load, the euclidean distance will be on the origin attributes. Later after you solve, you can "add" these values to the paths. OR, you can use the Closest Facility Solver and map your origins as Incidents and destinations as Facilities AND map the "distance" to the appropriate attr_<length> field in load locations. This will add the value of the "distance" of the input locations to the overall path computed. Regards, Jay Sandhu ... View more

make sure you right-click on the Feature Dataset that contains the street centerlines to choose the option to New netword dataset. Detailed instructions are here: http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Creating_a_network_dataset If it is still grayed out then it is likely the geodatabase is locked by someone else for editing and you are unable to create anything new in it. Regards, Jay Sandhu ... View more

If you want distances betwee pairs of points and not a complete OD cost matrix, then use the Route solver and load your start and end locations with the common survey number mapped to the ROUTENAME field (see the network location tab on the route layer pproperties). Then Solve. You will get one path per pair of stops. More on routename here: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00470000003t000000.htm Regards, Jay Sandhu ... View more

Slow loading demand points has nothing to do with location-allocation solver. Most likely you have a bad spatial index on your street feature class. Is it a shape file or file geodatabase? So check the index, create it if it does not exist (especially for shapefile) or re-create the index. Regards, Jay Sandhu ... View more