Hello! I am working on project right now where I have 11 layers (all layers are buffers) and I want to create a heat map based on how many layers (buffers) overlap. I am trying to follow these directions: http://forums.arcgis.com/threads/9740-Sum-of-Overlapping-Areas-Cells?p=33982&viewfull=1#post33982 because it seems to be exactly what I need to do, but I am not understanding the first part (union). I am trying to follow that direction by selecting all of my layers as the union input, but the union is not finishing (I have left it going for hours, I think this is because my data is so large). I was wondering if anyone knows a better way or a work-around that would get me what I am looking for. I am relatively new to ArcGIS (2 semesters) and I am using 10.1. I would really appreciate any help, thanks!!