Understanding Advanced Structure Options
When creating or editing structure you have access to some options which give you finer controls over the trim, cut, and fill.
Trim
Trimming options allow the structure to be trimmed against the surface generated by the contours and spots in either the Existing or Proposed sites. By default, your structures are set to None, and the structure boundary remains as it was created.
If you check Top To Proposed of Top to Existing, the top surface of the structure will be trimmed against the Proposed Site or the Existing Site.
Tip: Top to Proposed can be the best option for calculating banking and batter.
If you check Bottom to Proposed or Bottom to Existing the bottom surface of the structure will be trimmed against the Proposed Site or Existing Site. site.
Tip: If there are materials in the structure you are trimming from the bottom of, the structure will protrude above the surface by the material depth.
If setting a Trim option, you will need to indicate whether you are trimming to Inside or Outside from the Trim To options. Selecting Inside this will trim the structure and keep the part under the surface. Selecting Outside will trim the structure and keep the part above the surface.
Tip: In most cases select Inside for calculating batter and Outside for calculating banking.
Cut and Fill
You can specify what cut and fill calculations are performed for the structure. The default options for a Demolished structure are Fill Underneath and Back Fill, and for a Built Structure are Calculate Cut and Fill Underneath.
Calculate Cut and Fill Underneath will calculate the cut or fill respectively for the structure.
Trim Fill To Proposed is useful where a structure slab extends above the surface of the Proposed Site and you want to have fill underneath, but only to the point where the structure intersects the Proposed surface.
Back Fill indicates whether fill should be applied above the structure.
Respread Under is used in conjunction with Trim Fill to proposed and re-spreading, and if a structure extends beyond the surface of the Proposed Site, the respread will be extended under that structure extension.