I try to do conduct a Network Analysis using Service Area in Mosul district, Iraq (grey area).
My facilities are hospitals. I prepared a network dataset in ArcMap using a roads polylines shapefile (it looks that junctions and edges, in purple in the map, are well connected). I defined two modes, Driving and walking cost. However, when I run the analysis, it seems there is a problem, as if some roads seem not to be taken into account in the analysis, giving a kind of "erratic" service area. Would you have any advice / suggestion of what I could possibly do wrong in the process?