Vertical offset of Triangultion string

Hi,

We are doign re-enigeering design of a existing road which need to be widen and will also include some geometric improvements.For this we have been instructed to keep the vertical profile 300mm higher than exiting ground.

My question: Is there any way to vertically offset the existing Triangulation strings Tx00 by 300mm and then display both exising and offsetted surface in the Long profile creating window.

 We do not have the survey data cad file with us but only having Exiting trinagulation model.

Thanks