Can someone confirm for me if Network Analyst recognizes that not all intersecting streets are actually intersections. For example, streets with bridges? I am referring specifically to the TIGER lkA street files. I do not see any type of identifier that would include elevation in the table.
If NA does treat overlapping streets as intersections, what approaches can be taken to ensure that the routes are not generated requiring these impossible routes?
You can create a network dataset in a wide variety of ways. It can support end point connectivity (default) or any vertex connectivity. For end point, it assumes that street feature with a common end points will meet and you can transfer from one to another. You can override that with additional information such as elevation fields to indicate that there is a bridge or tunnel there so that proper connectivity is created. Without this additional information you cannot create correct connectivity. TIGER data's goal was to support the US census activity not provide the best routing data available. You will need to either enhance it with additional information or find another source such as open source map. However if you are planing to use TIGER, why not use the free streetmap data that ships with ArcGIS. It is on the Data and Maps DVD and covers all of North America. It is ready to route. It is not the most current data (i.e., it is free) but will be better than TIGER.
You can create a network dataset in a wide variety of ways. It can support end point connectivity (default) or any vertex connectivity. For end point, it assumes that street feature with a common end points will meet and you can transfer from one to another. You can override that with additional information such as elevation fields to indicate that there is a bridge or tunnel there so that proper connectivity is created. Without this additional information you cannot create correct connectivity. TIGER data's goal was to support the US census activity not provide the best routing data available. You will need to either enhance it with additional information or find another source such as open source map. However if you are planing to use TIGER, why not use the free streetmap data that ships with ArcGIS. It is on the Data and Maps DVD and covers all of North America. It is ready to route. It is not the most current data (i.e., it is free) but will be better than TIGER.
