Trimble Business Center

Is it possible to create a corridor template from existing 3D design linework, which has a variable offset distance from the master alignment string?

I'm not really sure if I understand your question.

But if you right click your corridor in the Project Explorer and "Edit" it you can add under Reference Lines as many 3D Polylines as you want to the corridor. They will show up as nodes in your templates, where you can connect them to build layers, or use them to limit your layers or offset surfaces.

Yes

Add the line as a Reference Line to the corridor. That will add it as a Node in the Node List of the Template. Then you can create a connection between the Node where you want the element to start and the node that is the 3D reference line. Reference lines just add named nodes to the node list in the Template Editor.

Typically for Finished Grade from Strings I will build the Road Surface using the strings in a normal Surface Model, then I add the Surface Model to the Corridor as a surface instruction - then to be able to add subgrades I add the reference lines to the corridor which allows me to create subgrade adjusted nodes to the reference lines and then make connections between the offset / elevation nodes.

I will also sometimes build the subgrade surface using copies of the Finished Grade Strings and then offset those strings down to base of subgrade etc to create the adjusted Finished Grade Model. Then add the Subgrade Adjusted surface to the corridor as Material Layer Subgrade to get my quantities by Section method. 

Or if your road subgrades are just for Box Outs I will use Site Improvements and create subgrade surface to create the subgrade adjusted surface.

If you need more help on any of these methods email me and I can set up a training for you

Alan