I'm working on a project that includes storm drains, streets, and watershed data. I grabbed the elevation data from a DEM of my study area and it is now in the intersection pointfile attribute table created by the network analyst. Now, I am trying to incorporate that data into the street layer. The idea is to find the most direct route stormwater would take to get to a body of water. Using Z-data from the intersection layer, how would I incorporate this into maybe making all the streets appear to be one-way, and going downhill? i am pretty sure I need to re-do the Network Dataset and somehow incorporate the elevation data into it somehow...but i am hitting a wall. Any suggestions would be great!