Incorporating existing drainage and utilities is described here: Drainage and Utilities

Assuming the Drainage and Utilities files are incorporated into the Project File Setup, you should have access to existing and proposed utilities (with live updates!) by simply turning on the appropriate reference files.  If not, you can simply attach the utilities and drainage files as reference files.

As the project moves forward you can evaluate how your new roadway and ancillary design interacts with existing and proposed utilities.  Conflict Detection can be automated, including hard conflicts and minimum distance violations.  The Detecting and Managing Utility Conflicts course in the Utilities Modeling Learning Path teaches you how to use the Conflict Detection tool in less than an hour.