Duct / Duct, Duct Bank / Duct, and Duct / Cable associations are managed through containment. That is to say each duct would have a containment association with the cable it contains and each duct back or duct would have containment associations with its corresponding ducts (sub-ducts are allowed in this model, finally). Unfortunately there are no products or extensions build around conduit management for the utility network yet so if you want cross sections you'll need to develop something yourself.
