Now im in doubt because i'm doing service areas for two countries. The results are so different in shape.
As you can see by the left image, the areas are in circle, otherwise the right image we have square areas.
Why is this happening? Can you help me?
Thanks in advance.
if you did it the same way using the same criteria, that might mean that the road networks of the two countries differ in their general configuration. Or... you did something differently. Or both. You will have to backtrack from your assumption that the patterns should generate similar geometry
My first guess would be as Dan Patterson surmised, that the analysis was run with different settings. In particular, were the Polygon Generation settings the same between both runs? The Polygon Type and Trim Polygon settings can make a large difference in the output.
As Joe Borgione suggested, there are is some information available on how to work with OSM data. I don't know quite so much about this aspect, but this gentleman at Esri does, so let me tag him in case he can offer some more insight: Jay Sandhu
If connectivity in the network has come up as an issue, consider running Topology on the source data used to create the network dataset (if you have that available) to find any disconnects. Note that it is common to run into disconnects in street data, as often the data was created with CAD, which does not snap the line ends to be coincident.
In terms of building a functional network dataset, this Esri link is very helpful for the workflow and the various aspects one has to consider:
Chris Donohue, GISP