The following 2 videos demonstrate creating a 3D Linestyle of guardrail components which can then be used by the Corridor Modeling commands while building the 3D model.
Click the video below to play it. To view in fullscreen mode, first click the YouTube link at the bottom of the video to launch the video on the YouTube site. Then, click the fullscreen button (rightmost button at bottom of video).
Part 1: Creating a 3D Linestyle
Part 2: Implementing a 3D Linestyle in Corridor Modeling