expression for TF/FT_MINUTES

Discussion created by plotnikoviv on Nov 5, 2013
Latest reply on Nov 10, 2013 by koushik_p77
You know there is Shape_Length field with the length of line features, which is calculated automatically.
I basically want to make my FT/TF_Minutes fields doing smth like the same - i ve got also Speedlimit field with km/hour, so the question is if it is pissible to calculate FT/TF_Minutes automatically everytime i change Speedlimit or Create new obj and so on.
The expressions seems to look like this:
[SHAPE_Length] * 60 / ([Spdlimit_F] * 1000)
[SHAPE_Length] * 60 / ([Spdlimit_B] * 1000
but i have no idea where can i put it. First i thought about Default Value in Feature Class properties, but it didnt work.
So i started my topic here cause its related to Network Analyst...