DRAFT B-101-1.1, B-101-2.0 base LOD beam guard EAT

Last updated: 2023-09-14

Model feature example download package version 1.1 (.ZIP)

Model feature example download package version 2.0 (.ZIP)

The DRAFT example version 1.1 and DRAFT example version 2.0 of the Base Level of Detail (Base LOD) beam guard EATClosed Energy absorbing terminal. This is the typical end of a section of beam guard. It includes geometry deflection, increased post placement, and terminal end. model feature are available for review. These DRAFT examples are part of Wisconsin DOT's effort to update our design model standards by utilizing 3D design objects to communicate level of detail expectations and other geometric requirements of design models.

More information about WisDOT's Design model standards update

The geometric elements of a Base LOD example will establish a feature-oriented standard for the minimum required level of detail for design model deliveries. These examples will define a standard that produces design models that are an accurate representation of design intent, and are consistent with plan sheets.

Design model features developed to a Base LOD will contain accurate geometric information, but less design geometry information than Advanced LOD features. Base LOD features are accurate, but may not be fully representative of proposed work.

Base LOD should focus designers' efforts on elements of design geometry that are most beneficial to construction project needs and representation of design intent. The Base LOD standard will minimize design efforts on elements that provide lesser construction project benefits.

Model feature examples define geometric requirements of design models including level of detail expectations and key elements of feature representation. Two Base LOD examples have been developed to represent earthwork grading to support beam guard EAT construction. Both examples comply with the geometric requirements of standard detail drawing SDD 14b-44a Midwest Guardrail System (MGS) Energy Absorbing Terminal (EAT) - Layout. We are intending to promote both DRAFT Base LOD examples to Guidance status, pending industry comments. Geometric representations from either example would be acceptable in design model deliveries. Regions may choose to specify one method over the other for their project designs.

B-101-1.1 Base LOD beam guard EAT example

Example version 1.1 closely follows the earthwork geometry as depicted in the standard detail drawing. It creates cross section slope breaks at the locations of the standard detail drawing's (SDD's) Hinge Point Line and Gradeline. Designing beam guard EAT earthwork in this manner will yield the narrowest roadway cross section footprint allowable by the SDD geometric requirements. However, it also results in more complex slope geometry, and is more difficult to construct due to the narrow widths of slope areas.

Figure 1: Image clipped from Standard Detail Drawing SDD 14b-44a with model example stationing identified of key geometric transition locations

Figure 2: Isometric view of DRAFT B-101-1.1 Base LOD beam guard EAT Top surface model with corridor breaklines

Figure 3: DRAFT B-101-1.1 model example with standard detail drawing Gradeline and Hinge Point Line features accentuated

Figure 4: DRAFT B-101-1.1 model example with side slope transition configuration accentuated

Figure 5: Narrow width cross section elements makes the B-101-1.1 design geometry difficult to construct

B-101-2.0 Base LOD beam guard EAT example

Example version 2.0 simplifies the configuration of side slope geometry compared to the slope configuration in B-101-1.1, and is in compliance with the geometric slope requirements of SDD 14b-44a. It maintains a minimum cross slope width of 8' for side slope elements. Version 2.0 is easier to design, it's design geometry is easier to understand and communicate, and it makes the earthwork easier to construct than B-101-1.1.

A negative aspect of the B-101-2.0 slope configuration is the roadway cross section footprint is wider than B-101-1.1 through the beam guard EAT area. The width variance is sensitive to the specific geometry of the location, in this example the difference is 5.5' at the widest point – the intersection of the Gradeline and the Clear Zone Limits.

Another negative aspect of version 2.0 slope configuration is the clear zone slope transition occurs at a distance that is further along the roadway from the start of the EAT (compared to the slope transition of version 1.1), and may require a greater overall length beam guard installation. In version 1.1, all side slopes are transitioned to 2.5:1 by station 400+37.34. In version 2.0, all side slopes are transitioned to 2.5:1 by station 400+87.34, 50 feet further away from the start of the EAT than version 1.1.

Figure 6: Isometric view of DRAFT B-101-2.0 Base LOD beam guard EAT Top surface model with corridor breaklines

Figure 7: DRAFT B-101-2.0 model example with standard detail drawing Gradeline and Hinge Point Line features accentuated

Figure 8: DRAFT B-101-2.0 model example with side slope transition configuration accentuated

Figure 9: The greatest roadway footprint width difference between the two Base LOD beam guard EAT examples is 5.5', occurring at the end of the Gradeline

Consistency with SDD 14b-44a

Both example version 1.1 and example version 2.0 meet the geometric roadway requirements for beam guard energy absorbing terminal construction as shown in SDD 14b-44a.

Special corridor frequency locations

The following locations are key points in the geometric transitions associated with this feature, and must be represented in the C3D corridor. Model example stationing is used to help identify locations.

B-101-1.1
Feature Station in example
The start of the 15:1 widening taper of the HINGE POINT LINE 398+35.23
Post 1 399+53.67
Post 5 399+78.67
The start of GRADELINE targeting, coinciding with the start of the shoulder foreslope's 25 FT long slope transition from 4:1 to 2.5:1 399+93.56
Post 9 400+03.67
The end of the shoulder foreslope's 25 FT long slope transition from 4:1 to 2.5:1 400+18.56
The end of GRADELINE targeting, clear zone slope transitioned to 2.5:1 400+37.34

Optional special frequency location at start of shoulder pavement widening. SDD 14b-44a does not specify widening of shoulder pavement. However, some project designs do widen the shoulder pavement to match the face of beam guard, and this example has shoulder pavement widening included in its design concept. When the shoulder pavement is widened it affects cross sectional geometry and therefore the start of the widening taper should be depicted in the corridor with a special frequency.

 399+03.67

Figure 10: BaseLOD beam guard EAT Version 1.1 special corridor frequency locations

B-101-2.0
Feature Station in example
The start of the 15:1 widening taper of the HINGE POINT LINE 398+35.23
Post 1 399+53.67
Post 5 399+78.67
Post 9, coinciding with the start of the shoulder foreslope's 25 FT long slope transition from 4:1 to 2.5:1 400+03.67
The end of the shoulder foreslope's 25 FT long slope transition from 4:1 to 2.5:1. 400+28.67
The start of the clear zone's 50 FT long slope transition from 4:1 to 2.5:1 400+37.34

The end of the clear zone's 50 FT long slope transition from 4:1 to 2.5:1

 400+87.34
Optional special frequency location at start of shoulder pavement widening. SDD 14b-44a does not specify widening of shoulder pavement. However, some project designs do widen the shoulder pavement to match the face of beam guard, and this example has shoulder pavement widening included in its design concept. When the shoulder pavement is widened it affects cross sectional geometry and therefore the start of the widening taper should be depicted in the corridor with a special frequency. 399+03.67

Figure 11: Base LOD beam guard EAT Version 2.0 special corridor frequency locations

Clear zone slope transition of B-101-2.0

B-101-2.0 transitions the roadway side slope within the clear zone from 4:1 to 2.5:1 over a distance of 50 FT.

Shoulder foreslope transition distances

B-101-1.1 transitions the shoulder foreslope slope from 4:1 to 2.5:1 over a distance of 25 FT.

Design model files in Construction Data Packet required formats

These files are representations of the design model deliverables which would be included in contractor data packets (see FDM 19-10-43.10 for design delivery requirements and CMM 7-10.3 for construction responsibilities)

  1. BaseLOD-BGEAT-draft1-1.xml; BaseLOD-BGEAT-dft2.xml
    1. TOP and DATUM (finished earthwork) DTM surfaces in LandXML v1.2 format, this file meets surface model delivery requirements for WisDOT contractor data packets.
  2. ACAD-BaseLOD-BGEAT-CrdrBreaklines-dft1-1.dwg; ACAD-BaseLOD-BGEAT-CrdrBreaklines-dft2.dwg
    1. TOP and DATUM Breakline file in AutoCAD format, this file meets breakline delivery requirements for WisDOT contractor data packets.
    2. All Civil 3D corridor graphical elements are also included in AutoCAD format, layer name conventions are used to identify elements used in the designer's surface model definition.
      1. Elements representing the TOP surface model are identified by layers named specific to TOP elements.
      2. Elements representing the DATUM surface model are identified by layers named specific to DATUM elements.
      3. Elements representing both the TOP and the DATUM surface model are identified by layers named specific to TOPDATUM elements. TOPDATUM classification is used when the TOP and DATUM surface models are coincident.
  3. ACAD-BaseLOD-BGEAT-Datum3DFace-dft1-1.dwg; ACAD-BaseLOD-BGEAT-Datum3DFace-dft2.dwg
    1. DATUM (finished earthwork) surface model triangle file in AutoCAD format, this file meets TIN triangle delivery requirements for WisDOT contractor data packets.
  4. ACAD-BaseLOD-BGEAT-Top3DFace-dft1-1.dwg; ACAD-BaseLOD-BGEAT-Top3DFace-dft2.dwg
    1. TOP surface model triangle file in AutoCAD format, this file meets TIN triangle delivery requirements for WisDOT contractor data packets.

Non-Construction Data Packet files

These files are not Construction Data Packet deliverables:

  1. c3d-BaseLOD-EAT-draft1-1.dwg; c3d-BaseLOD-EAT-draft2.dwg
    1. Civil 3D design data that produced the model feature example. This file is provided for informational purposes only, it is not intended to convey Civil 3D project delivery requirements or design model delivery requirements.
    2. Workflow used in development of the Civil 3D design data for this model feature example may not be consistent with best MDU workflow recommendations. It is one way to produce design content.
    3. Content of file and data structure is not consistent with Civil 3D project delivery requirements, all data is in a single dwg. Data was structured in this manner for convenience of sharing model feature example source data.
  2. ACAD-BaseLOD-BGEAT-DatumContour-dft1-1.dwg; ACAD-BaseLOD-BGEAT-DatumContour-dft2.dwg
    1. DATUM (finished earthwork) surface model contours (0.2' major, 0.05' minor) and surface model boundary in AutoCAD format. Contour files are not required in WisDOT contractor data packets, but contours could be added as a required design deliverable if the contracting industry indicates they are useful. Contour files are produced from Civil 3D design data with little effort and are an effective visual representation of surface models.
  3. ACAD-BaseLOD-BGEAT-TopContour-dft1-1.dwg; ACAD-BaseLOD-BGEAT-TopContour-dft2.dwg
    1. TOP surface model contours (0.2' major, 0.05' minor) and surface model boundary in AutoCAD format. Contour files are not required in WisDOT contractor data packets, but contours could be added as a required design deliverable if the contracting industry indicates they are useful. Contour files are produced from Civil 3D design data with little effort and are an effective visual representation of surface models.
  4. BaseLOD-BGEAT-CrdrBreaklines-dft1-1.pdf; BaseLOD-BGEAT-CrdrBreaklines-dft2.pdf
    1. PDF provided for non-C3D users who would like to review model examples. 3D PDF file with graphical representation of model breaklines and additional corridor elements.
  5. BaseLOD-BGEAT-Datum3DFace-dft1-1.pdf; BaseLOD-BGEAT-Datum3DFace-dft2.pdf
    1. PDF provided for non-C3D users who would like to review model examples. 3D PDF file with graphical representation of DATUM TIN triangles.
  6. BaseLOD-BGEAT-Top3DFace-dft1-1.pdf; BaseLOD-BGEAT-Top3DFace-dft2.pdf
    1. PDF provided for non-C3D users who would like to review model examples. 3D PDF file with graphical representation of TOP TIN triangles.
  7. BaseLOD-BGEAT-DatumContour-dft1-1.pdf; BaseLOD-BGEAT-DatumContour-dft2.pdf
    1. PDF provided for non-C3D users who would like to review model examples. 3D PDF file with graphical representation of DATUM (finished earthwork) contours.
  8. BaseLOD-BGEAT-TopContour-dft1-1.pdf; BaseLOD-BGEAT-TopContour-dft2.pdf
    1. PDF provided for non-C3D users who would like to review model examples. 3D PDF file with graphical representation of TOP contours.

Are you interested in seeing what people are saying about the DRAFT model examples? See the Design Model trello team board page for discussions about our DRAFT status design model examples. If you’d like to share your thoughts and ideas, check out the Design model examples commenting and feedback #design section of the Design model features example library to get started.

We welcome comments and questions of any subject concerning the model examples. Here are a few issues we’d like you to consider and would like to hear from you about:

Level of Detail

  1. Is there sufficient design detail for less complex project situations?
  2. Are all critical geometric elements of the roadway project captured in this Base LOD example?
  3. Does this level of detail support production of plan cross sections at traditional cross section locations and frequencies for this type of work?

Slope geometry

  1. Questions or concerns regarding compliance with SDD 14b-44a?
  2. Are there alternative slope configurations that should be considered in addition to example versions 1.1 and 2.0?

Clear Zone slope transition length of B-101-2.0

Quoting from FDM 11-15-1.11 article on side slopes: "Gradual transitions from cut to fill slopes, or within cut or fill slopes, will avoid unattractive bulges and sharp depressions. Do not vary fill slopes of adjacent full stations by more than 1:1, except under unusual conditions."

B-101-2.0 transitions the roadway side slope within the clear zone from 4:1 to 2.5:1 in a distance of 50’, 1/3 the distance that is called for in 11-15-1.11. The example transitions the clear zone slope more quickly because there is a safety benefit from the quicker transition in that it results in a shorter overall length of beam guard installation. There is a slight construction cost reduction in the quicker transition because of the shorter overall length of beam guard installation. Do these benefits outweigh the aesthetic concerns of unattractive bulges and sharp depressions that can be cause by quicker slope transitions?

Shoulder foreslope slope transition length of B-101-1.1 and B-101-2.0

Both example versions transition the shoulder foreslope slope from 4:1 to 2.5:1 over a distance of 25’. The location of this transition is protected by the beam guard and is compliant with SDD 14b-44a.

  1. Any concerns or comments about the transition distance or location?
  2. Any concerns about constructability of the shoulder foreslope transition over a distance of 25’?

File Content and Format

Questions for users of contractor data packets:

  1. The corridor breakline file is a graphic representation of Civil 3D corridors with surface model definition elements identified by Layer naming. There are extra graphical elements in the file such as corridor links (cross section elements) at each corridor frequency location (including plan cross section locations, plus additional locations not in plan cross sections). Do users of Contractor Data Packets see value or benefit in the provision of the corridor cross section elements, categorized by surface model type in the AutoCAD layer names?
  2. Is the contour file a useful deliverable as a representation of surface models?