# Cumulative calculation in a network

Discussion created by TSEDLACEK on Oct 2, 2013
Hi all of you smart GIS folks...

What I am trying to do is calculate accumulated time of flow through a sewer pipe network i.e. how much time elapses flow-wise between a given point and the treatment plant..  All the pipes are connected and flowing in the correct direction and I can run a trace from point A to point B.  I can calculate the time it takes for water to flow through each individual pipe given slope and pipe length, but what I'm having a difficult time figuring out is how to accumulate those times up the network.  In other words , it takes 1 minute for a slug of water to flow through pipe A.  It then takes 2.5 minutes to flow through the next upstream pipe, B, so the cumulative time in pipe b would be 3.5 minutes and so on.  My question to you all is: is there a way to calculate a field based on a field in a previous pipe segment in a network (A+B=C, B+C=D... etc)?

Any ideas would be appreciated...