I creataed a simple service layer polygon in network analyst(ArcGIS Desktop 10.2) with no heirachies set in the street network. Now I don't udnerstand why is this polygon created along some particular streets? Why isn't is properly spread out? For example why doesnt the polygon cover the areas/streets I have marked in red?(obviously those marked areas are also within 1km atleast, then why not form there?) The impedence is 1km and 2kms respectively. The streets are also well connected individual line elements as you can see the junctions.