> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/bebo-precast-arch-bridge-workflow/precast-concrete-arch-fill-bebo.md).

# Precast Concrete Arch Fill \[BEBO]

The Precast Concrete Arch Fill object models the structural fill placed over the arch, or between two stem walls, and computes its earthwork quantities. Its top and bottom surfaces can each be driven by a roadway, a fixed elevation, the stem walls, or a terrain model.

## General

**Structural Fill Position\[Above the arch=0/Between two stem wall=1]:** Selects where the fill sits — over the arch, or in the space between two stem walls (default: Above the arch=0).

**Arch:** The precast arch the fill is placed over.

**Stem Walls:** The stem walls bounding the fill.

**Fill Width:** Width of the fill across the structure.

**Downstation Boundry Long. Offset (Along PGL):** Longitudinal offset of the down-station fill boundary, measured along the PGL (default: 0).

**Upstation Boundry Long. Offset (Along PGL):** Longitudinal offset of the up-station fill boundary, measured along the PGL (default: 0).

**Downstation Width (Stem wall only):** Fill width at the down-station end. Applicable when the fill is bounded by stem walls.

**Upstation Width (Stem wall only):** Fill width at the up-station end. Applicable when the fill is bounded by stem walls.

**Transverse Offset:** Transverse offset of the fill from the alignment (default: 0).

**Width Option \[Input=0/Match Arch Width=1]:** Chooses whether the fill width is entered directly or follows the arch width (default: Input=0).

## Top Boundary

**Top Boundary\[Roadway=0/Elevation=1/Stem Wall Tops=2/DTM=3]:** Selects what defines the top surface of the fill — a roadway, fixed elevations, the tops of the stem walls, or a digital terrain model (default: Elevation=1).

**Roadway:** The roadway that defines the top of the fill. Applicable when Top Boundary is Roadway.

**Vertical Offset from Alignment (Roadway):** Vertical offset applied below the roadway surface when the top boundary follows a roadway (default: 0).

**Downstation Top Elevation:** Elevation of the top of the fill at the down-station end. Applicable when Top Boundary is Elevation.

**Upstation Top Elevation:** Elevation of the top of the fill at the up-station end. Applicable when Top Boundary is Elevation.

## Bottom Boundary

**Bottom Boundary\[Elevation=0/Stem Wall Top=1/Stem Wall Bottom=2/DTM=3]:** Selects what defines the bottom surface of the fill (default: Stem Wall Bottom=2).

**Down Station Bottom Elevation:** Elevation of the bottom of the fill at the down-station end. Applicable when Bottom Boundary is Elevation (default: 0).

**Up Station Bottom Elevation:** Elevation of the bottom of the fill at the up-station end. Applicable when Bottom Boundary is Elevation (default: 0).

## Terrain Data

**Grade DTM:** Digital terrain model used when a boundary is set to DTM.

**Terrain Data:** Terrain sample data derived from the selected DTM.

## Display

**Number of Segments:** Number of segments the fill solid is drawn with (default: 40).

**Show Fill\[No=0/Yes=1]:** When Yes, the fill solid is drawn in the 3D view (default: Yes=1).

**Display Opacity:** Opacity used when drawing the fill solid (default: 0.7).

## Quantities

**Gross Fill Volume:** Fill volume, before deducting the arch and wall volumes. (Read-only)

**Bottom Surface Area:** Area of the bottom surface of the fill. (Read-only)

**Fill Top Surface Area:** Area of the top surface of the fill. (Read-only)

**Average Fill Depth:** Average depth of the fill over its footprint. (Read-only)


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