I had this question come in today as to how to draw a profile of a Water Line in a plan and profile drawing so that the waterline in the plan and profile would dynamically update in line with changes to the road profile. The user has a lot of rock in their territory and they wanted to adjust a road profile and have the water line profile adjust dynamically with changes to the road profile so that they could instantly see the effect of the road profile changes on the water line in relation to the existing ground and the rock surface profile for the route. They were trying to minimize the amount of trenching that they would have to do for the water line in the rock layer, thereby value engineering the project for the client.
There are two main ways that you could do this …
Create the water line line for the crown of the pipe and the base of the pipe in 2D and then use the Vertical Design tool to elevate the two lines from the road centerline profile using the cross DZ function, that ties the lines at a fixed vertical offset to the profile of the alignment. That way if the profile of the road changes, the water line also changes in profile to maintain the Cross DZ elevation difference defined in the vertical design. The lines can then be added as reference lines to the corridor model and that allows them to be drawn in the Plan and Profile sheets.
The video shows how this is done
The alternative would be to create a second corridor model / corridor surface for the Top and Bottom of Water Line that follows the HAL of the road horizontally, and that is computed using Offset Elevation instructions from the PGL of the road - create two instructions to build the Water Line - Top of Pipe Model and also a Water Line - Base of Pipe Model as two material layers in Corridor 2. You can then create those two material layers as corridor surface models that are dynamically linked to the same HAL / VAL as the first corridor model. Now you can add the two surfaces as reference surfaces to the first corridor model so that they are attached to the first corridor, and you can now plot them in the Plan and Profile Sheets as necessary.
The video shows how this is done.