Network dataset

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03-17-2013 05:16 PM
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New Contributor
I am currently working with network dataset I got from the Open street map for London (UK) street map, after building the dataset in ArcCatalogue it returned some errors but built the network dataset anyway I could not perform some analysis like the closest facilities and other analysis. The best route analysis drew some route but I doubt it is accurate as the visual display does not look logically correct. I am not sure if it is anything to do with my dataset. What could be wrong?
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MVP Esteemed Contributor
What could be wrong?


Short answer. A lot of things, especially:

Connectivity and Impedance Values

My suggestion is to get more familiar with NA by working through the tutorial.
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Short answer. A lot of things, especially:

Connectivity and Impedance Values

My suggestion is to get more familiar with NA by working through the tutorial.


Could it be the dataset because I have worked through the dataset again? I just am wondering the the fields required to for the dataset to work alrightt.

Regards,

Olawumi
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I am not familiar with the OSM data quality of the London area, but when I used OSM Data from Hamburg with the Network Analyst I for example had problems with oneway streets (editing needed for ArcGIS to recognize them properly), prohibited turns onto highways (missing z-levels, bad connectivity set-up) and maxspeed data (many values not existent).

Not being able to perfom some types of analysis like Closest Facility seems rather odd though. What exactly happens when you try to do that?
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Esri Regular Contributor
With OSM data, make sure you are using "Any Vertex" connectivity and not the default End Point.

Jay Sandhu
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I am not familiar with the OSM data quality of the London area, but when I used OSM Data from Hamburg with the Network Analyst I for example had problems with oneway streets (editing needed for ArcGIS to recognize them properly), prohibited turns onto highways (missing z-levels, bad connectivity set-up) and maxspeed data (many values not existent).

Not being able to perfom some types of analysis like Closest Facility seems rather odd though. What exactly happens when you try to do that?


Thanks for your response. When I ran the closest facility the last time here are the warning error I got: "Warning: Location "57 A4020, LONDON, W5 5" in "Incidents" is on a non-traversable network element position.
Warning: Location "101 RIDGEWAY, LONDON, W3 8" in "Facilities" is on a non-traversable network element position.
Warning: Location "195 A502, LONDON, NW1 8" in "Facilities" is on a non-traversable network element position.
Warning: Location "STATION STREET, E15, E15 1" in "Facilities" is on a non-traversable network element position.
Warning: Location "BONDWAY, LONDON, SW8 2" in "Facilities" is on a non-traversable network element position.
Warning: 0 location(s) in "Incidents" are valid.  Need at least 1 valid location(s).
Warning: 0 location(s) in "Facilities" are valid.  Need at least 1 valid location(s).
Error: Insufficient number of valid locations in "Facilities" or "Incidents".

My minute Field rows are all null value, how can I calculate this to return figures?
Regards

Olawumi
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Location XY is on a non-traversable network element position.
Warning: 0 location(s) in "Incidents" are valid.  Need at least 1 valid location(s).
Warning: 0 location(s) in "Facilities" are valid.  Need at least 1 valid location(s).
Error: Insufficient number of valid locations in "Facilities" or "Incidents".


Your Incidents and Facilities are on street elements that are either not connected to the rest of the network (for example because of little gaps from the endpoints to the next street elements), or there are some restrictions active that prevent using this street (use the network identify tool to check, or turn restrictions off in the analysis settings).

My minute Field rows are all null value, how can I calculate this to return figures?

For example with the field calculator and a little math using a speed value (30mph?) and the shape length attribute.
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Your Incidents and Facilities are on street elements that are either not connected to the rest of the network (for example because of little gaps from the endpoints to the next street elements), or there are some restrictions active that prevent using this street (use the network identify tool to check, or turn restrictions off in the analysis settings).


For example with the field calculator and a little math using a speed value (30mph?) and the shape length attribute.


Thanks for your prompt response to my queries. I am happy to tell you that it worked. However I am struggling with service area analysis with this error messsage "Warning: All network edges were excluded from line/polygon generation for "all facilities" in "Facilities".

Regards,

Ola
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New Contributor II

Hi Olawumi Lanlehin,

Have you figured out the problem with London road network? 

Currently, I am doing my dissertation and I need to run a network analysis (Closest facilities) on London roads. I have a similar problem as yours and was looking through websites and blogs to find a solution which I came across to the discussion that you've started. 

I just was wondering whether you might be to help me now. Many thanks in advance.

looking forward to hearing from you.

Regards

Shohreh

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Esri Regular Contributor

If you are using Open Street Map data, I would suggest that you look at the tools at the link below to help build a network dataset that can be used with ArcGIS. 

ArcGIS Editor for OpenStreetMap | Overview 

Alternatively you can use the closest facility service on ArcGIS.com and do your analysis there. You will be paying some credits to use that. But the network of London is available ready to use.

What are the ArcGIS Online network analysis services?—Help | ArcGIS Desktop 

Jay Sandhu

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