centre_for_cities

Distance travelled to work query

Discussion created by centre_for_cities on Apr 11, 2011
Good afternoon

I was wondering if I would be able to ask for some assistance please? I have a polygon layer of wards (an administrative boundary) and I have data which tells me which ward people live in and which ward that same person works in. What I would like to be able to do is calculate the distance (straight line) they travel to work. I would then like to aggregate up data on distance travelled to work at ward level to the local authority level (a larger administrative boundary). So this would require looking at each person living in a ward in the local authority and knowing the distance they travelled to work. I would then add these distances together and divide them by the total number of employed residents to get an average of the distance travelled to work.

The version of Arc GIS I have is 9.2. I dont have any of the extensions such as spatial analyst although free 60 day trials of these are available at the moment so if I need one of these I could use it for a short space of time and purchase it if it is useful.

From some reading I have done I think that I need to convert the polygon layer of wards I have into a points file which contains the centroid of each ward. I have tried adding X and Y centorid coordinates to the attributes table of the wards polygon file and although I get Y coordinates I just get a column of zeros for the X coordinate. I'm not sure why this is happening or if I should be approaching the task in a different way.

Once I have the centroid coordinates I could add the data I have on where people live and work. I then thought I might be able to use Hawths analysis tool to calculate the distance between the centroids of each combination of wards. Once I have this information I thought I could multiply each distance by the number of employees making that journey. Somehow I would then need to be able to aggregate this data up to ward level. Prehaps these final calculations are best done in Excel if I exported the distance travelled from ward to ward data.

I am slightly lost as to what is the best way to go about this task so any clear and explicit information (I am a GIS novice) would be much appreciated.

Best wishes

Rachel

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