Latest Contributions by JaySandhu

You can visualize the digitized direction of your streets by using a line symbol that places an arrow in the middle of the road, for example pick a line symbol like the one titled: Arrow Right Middle. You can also draw the network dataset symbolized with the directions in which the lines are restricted based on a restriction attribute such as oneway. Bring up the properties of the network dataset (added to the ArcMAP table of contents) and click on Symbology tab and turn on edges and pick the arrow symbols and customize as needed. More help here: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/The_network_dataset_layer/0047000001r4000000/ Jay Sandhu ... View more

Here is an old forum post about this topic: http://forums.esri.com/Thread.asp?c=93&f=993&t=238308 and another link to .Net resources: http://help.arcgis.com/en/sdk/10.0/arcobjects_net/conceptualhelp/index.html#/How_to_load_data_into_a_network_analysis_problem/00010000023q000000/ Jay Sandhu ... View more

Theresa, You can accomplish this by doing two things. First, use the GP tool Calculate Locations which in addition to computing the network locations, also adds a field called Distance with the distance of the point to the network. When you do this, make sure the data is projected so that you do not get the distance in decimal degrees. Second, let's assume that you are solving on Miles and the Distance field has been populated in miles as above. Create a Route Layer and use Load Location to load the points. The Use Network Location Fields will be selected automatically and in the Location Analysis Properties, for the Attr_Miles (or what ever your impedance attribute name is), for the default value, click on the colum to get a drop down list of available attribute and choose Distance. Now when you click ok to load the locations, it will have mapped the off road distance to the Attr_Miles. Now solve. And the resulting path length will be the addition of the off road distance and the shortest path length. Jay Sandhu ... View more

ArcGIS can use 4 GB if you are running it on a 64bit OS like Windows 7. So are you still not able to compute all paths for 418 Incidents and 32 Facilities? That is 418 by 32 is 13,376 line feaatures and if your network dataset has good connectivity then it should be quick to compute and not run of memory. Perhaps there is something going on with your network that is causing memory or performance issue. What kind of network do you have? Jay Sandhu ... View more

Looking at your screen shot, it looks likely that the line barriers caused some areas of the network to be not traversable and cause some edges not reachable. So I would suggest you could try using generalized instead of detailed to get a slightly better result or you will have to resport to runing Clip on the resulting polygons with the district boundary. You could automate it within model builder... Jay Sandhu ... View more

If you are using ArcGIS 10, then you can use the Line barriers to restrict the service area. Convert the district boundary polygons into line features using the GP tool Feature To Line Then load these line features as Line Barriers into the services area as restrictions (not scaled cost barriers) Solve your hospital service areas and they will not cross the district boundaries! Jay Sandhu ... View more

Service area polyons are generated around the lines that are traversed from the start location (facility). When the facilities are not on the network, say 5000 meters away and you are only asking for a 400 m service area, then the polygon will not cover the facility. However do note, that it covers the start location, or the location where the facility was located on the network. As far as trim, for a 400 m service area, I would set it around 25 meters. And what it does is trim the service area polygons to better hug the outer set of edges. Normally the shape of the polygon is dictated by finding a boundary between the streets that were traversed and streets that were not traversed. This can result in a jagged polygon in some areas. Using trim keeps the polygon boundary within a certain distance from the traversed edges. You can read more about the Trim towards the bottom of this web help page: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Service_area_analysis/004700000048000000/ Jay Sandhu ... View more

The Find Route will give you a route between two or more locations. To do find closest, you would have to use it many times between each pair of stops and then find the 5 closest. Why not use the NA built in solver for Closest Facility? You could use the free network that comes with ArcGIS. It is on the data and maps dvd and is called Streetmap. Jay Sandhu ... View more

The end points of lines have to be exactly coincident for a network dataset to find connected edges. Most likley your data is not connected when you zoom in closer. One way to check connectivity is to use the network identify tool. It is the second icon from right on the NA toolbar. Click on any edge and it will show it's values as well as what it is connected to. Use it in the locations you cannot find a path to see if connectivity is the problem. You could try to fix connectivity problems automatically with the GP tool Integrate. Make sure to make a copy of your data first as it will modify the existing data and if you choose a wrong tolerance, it may collapse some features. You can read more about it here: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Integrate/00170000002s000000/ Once you integrate, rebuild the network dataset. Jay Sandhu ... View more

A) the permeability layer did not auto appear in the new network dataset though it has been imported to file Geodatabase feature dataset - is there any criteria for the required layers to appera in the new network dataset? A polygon layer cannot be made part of a network dataset as it is only made from lines and points (if needed). However at analysis time, you can bring in such data as scaled cost polygon restrictions. For example, create a Route Analysis layer and then in the NAWindow, right-click on the polygon barriers and choose Load Locations to load these polygons in (as Scaled Cost and not Restrictions) and then choose an appropriate value to scale the cost of going through that area. Note that these polygons only "scale" the edges or junctions that are inside them. You cannot travel where edges do not exist. B) In ArcMap, when i test the find shortest route. "No route found" is displayed whenever it crosses the pedestrian crossings or when there is a gap in between the footpath layer. How do i join the gap or how do i link it with the driveway layer to make the network continuous? You will have to edit your street data to add the missing edges that connect the gaps. Make sure snapping is on so that correct connectivity is built. Jay Sandhu ... View more

Network Analyst traverses the network. So as long as you have edges that connect places where you can travel, a path can be found. You could connect a footpath to another footpath, midway, with another edge. Take a look at the Paris network in the NA tutorial on how to add additional edges to connect the road to the metro network. Jay Sandhu ... View more

If by London underground you mean the map where all the rail lines are offset? Well you will have to establish connectivity with extra links for the transfer points. You could take a look at the Paris network in the Network Analyst tutorial on how to connect two different modes together. Just remember that the route solver does not have a way to honor the train schedules. Jay Sandhu ... View more

Not that add-in directly. You could take the original code (it's in the SDK) and turn it into a standalone executable then be able to call it from Python. At 10.1 we are adding this as a GP tool. So you could sign up for 10.1 beta and try it out! Jay Sandhu ... View more

The first question that came to my mind is why do you need such verification. If you build a network on your streets, the junctions are automatically created....in any case what you need to do is the following: Assuming that you have a feature class of streets and a feature class of points. You can run the gp tool Spatial Join. it is in the Analysis tools for Overlay. Set the Target feature to be the point feature class and the Join Features to be the line feature class and choose the Join operation to be JOIN_ONE_TO_MANY and run the tool. It will create a new point feature class that will have joined over all the fields from the Line feature class. Now you can simply select the points where the ID of the point does not match the F_NODE or the T_NODE. Jay Sandhu ... View more

Bring up the properties of the RoadLinks feature class. Then click on the Fields tab. It should show you all the fields that are present in your feature class. See if any of them are un-checked to hide them from view when you open the feature class. Most likely the ObjectID field has been turned off. if that is the case, check it on and now the values should be visible. Jay Sandhu ... View more