Level of Detail
The following information supplements PDDM Section 9.6.1.
Digital Design Data
Develop highway design surveys and road designs using Bentley GEOPAK and/or(?) Open Roads software. Provide design data in native MicroStation file formats compatible with these programs. These may include:
- MicroStation design files (DGN files) including plan and profile view geometry and cross-sections;
- Existing ground terrain models as a Triangular Irregular Network (TIN) in both GEOPAK TIN and Land XML formats;
- GEOPAK Coordinate geometry data provided in its native GEOPAK format (GPK files); and
- 3D digital design model representing the proposed finished grade surface (and other secondary surfaces when applicable) in GEOPAK TIN, Land XML and InRoads DTM formats.
Adhere to current FLH CADD standards. Submit a Design File Log listing all files with a description of the file's content (i.e. GPK file with all chains and profiles listed, DGN files, etc.). Specify the coordinate system, datum and any project projection factors used to establish mapping control. Obtain coordinate systems, datums and projection factors from the original base map.
MicroStation Design files contain 2D or 3D proposed plan and profile view or cross-section geometry. Plan view geometry includes items such as pavement edges, shoulders, curbs, gutters, sidewalks, retaining walls or any other feature used in the generation of a 3D model. Cross-section geometry refers to the master proposed cross-section files (not the cross-section sheets) for all alignments found in the GPK file, if applicable. Proposed cross-section files are required to include the GEOPAK cross-section cells. The files include all existing ground lines including subsoil conditions, proposed templates including all pavement, shoulders, curbs, gutters and sidewalks, and all other side slope conditions.
Existing Ground 3D Model represents the existing ground conditions as provided by FLH, third party surveyor or a combination of both. The file is submitted both in the native GEOPAK TIN and LandXML format.
Coordinate Geometry Data contains all final alignments used in the development of the contract plans. Alignments include all chains, existing and proposed profiles, control points and any special profiles used for drainage purposes or other design features such as sidewalks, retaining walls, etc. Remove all preliminary alignments from the coordinate geometry file. Create descriptive names for all geometry contained in the GPK file that are representative of the designed alignments and features found in the plans. Provide the coordinate geometry information in both the native GEOPAK (.gpk) format and the LandXML version.
Superelevation Transitions: Submit files containing all transition points showing stationing, cross-slopes, superelevation rates, runoff lengths and runout tangent lengths. Submit the superelevation transitions in ASCII text format as generated using the GEOPAK superelevation tools. In addition, include the MicroStation pattern-shape file generated using the GEOPAK superelevation tools.
Submit an all-inclusive 3D Digital Design Model of the project corridors as a design data deliverable. At a minimum, create surfaces representing the proposed finished grade AND a surface representing the subgrade, or top of aggregate (both should daylight to the side slopes). Submit the 3D digital design models in the GEOPAK TIN or OpenRoads DGN, and LandXML formats.
3D Model Application During Design Development
Exhibit 9.6.1A-1 illustrates the types and uses for 3D design data reviewed during any stage of the project design. Each design stage adds additional model elements and uses; therefore continue to check information for prior stages.
| Design Stage | 3D Design Model Elements | 3D Design Model Uses |
|---|---|---|
| Preliminary Design | Existing conditions surface Low density proposed surfaces Proposed roadway corridor model Existing utilities |
Design results due to avoidance of sensitive resources such as cultural and wetlands Quantify impacts on sensitive resources, if any Minimize ROW impacts Compute quantities Plan surface drainage Create preliminary plans and estimate |
| Intermediate Design | Medium density proposed surfaces Proposed structures (external faces) Existing and proposed utilities Storm drainage systems |
Site distance checks Visual impact analyses Earthwork quantities Interdisciplinary design coordination Staging and constructability review Minimize utility relocations (clash avoidance) |
| Plan-In-Hand Design | High density proposed surfaces Proposed structures Proposed utilities Storm drainage systems |
Surface drainage review Create 3D graphics and 4D videos for ROW Acquisition and Public involvement Compute quantities Maintenance of Traffic conceptual plans Create ROW and utility relocation plans |
| Final PS&E Design | Very high density proposed surfaces Proposed structures (major systems) Final Storm drainage systems design |
Design validation and interdisciplinary review Compute final quantities Maintenance of Traffic review Create final contract plans and estimate Create 3D model reference data |
| PS&E Approval | Very high density proposed surfaces Final roadway corridor model Final structures (major systems) Final proposed utilities Final storm drainage systems |
Create contract documents Create staking/layout design Create AMG/real-time verification models |
Level of Details for 3D Data
Each project type requires different features and a varying Level of Detail (LOD) to depict the design intent sufficiently accurately for 3D design reviews and use during construction. Due to schedule, scope, and/or budget constraints, the level of detail of the 3D data requirements may be left to the discretion of the design project manager. During the course of design it may be necessary to obtain additional data or to increase the level of detail of data previously collected.
There are various methods to create 3D models of highway design features:
- Corridor Model typical sections created (in GEOPAK Corridor Modeler) based on parametric rules placed at defined stations (template drops). This is the most common tool for modeling linear elements that are generally regular in shape parallel to the alignment. Standard uses of corridor models include roadways and ditches. Advanced uses of corridor models include retaining walls, bridge abutments and intersections.
- String Model uses rules (in Open Roads) to offset linear features horizontally and vertically. This is a common tool for modeling non-linear features that follow consistent rules perpendicular to the base feature. Standard uses of string models include drainage basins and parking lots. Advanced uses include intersections and lane transitions.
- Feature Modeling these 3D line strings can be either created manually or output from corridor or string models. This is a common tool for hand-grading small areas like around headwalls. Add features to surfaces as break lines.
- Subsurface Utility Modeling GEOPAK Drainage visualizes single bore pipes in 3D. Bentley Subsurface Utility Design and Analysis (SUDA) creates 3D models of subsurface utility pipes and structures of predefined shapes and dimensions. These models follow parametric rules to modify depths and lengths as structure inverts or locations change. They also are able to compute storm sewer hydraulics and incorporate design changes in the 3D model. The pipes and structures function as 3D Solid Models.
- 3D Solid Modeling other 3D elements usually created manually. A library of 3D solid model elements like standard headwalls, light standards, sign posts and other structures is under development.
| Feature | Design Method | Data Type |
|---|---|---|
| Roadways | Corridor Model | Alignment, Surface & 3D Line Strings |
| Side Slopes | Corridor or String Model | Surface & 3D Line Strings |
| Gore Areas | Corridor, String or Feature Modeling | Surface & 3D Line Strings |
| Intersections & Interchanges | Corridor or String Model | Alignment, Surface & 3D Line Strings |
| Sidewalks & Bike Paths | Corridor or String Model | Surface & 3D Line Strings |
| Lane Width Transitions | Corridor or String Model | Surface & 3D Line Strings |
| Headwall Grading | String Model | Surface & 3D Line Strings |
| Guardrail Berm Transitions | Corridor, String or Feature Modeling | Surface & 3D Line Strings |
| Benching Transitions | Corridor, String or Feature Modeling | Surface & 3D Line Strings |
| Bridge Abutments | Corridor or String Model | Surface & 3D Line Strings |
| Bridge Substructures | 3D Solid Modeling | 3D Line Strings |
| Bridge Superstructures & Decks | Corridor, String or Feature Modeling | Surface & 3D Line Strings |
| Stormwater Ponds, Ditches & Swales | String or Feature Modeling | Surface & 3D Line Strings |
| Drainage & Utility Pipes | Subsurface Utility Model | 3D Solid Models |
| Drainage & Utility Structures | Subsurface Utility Model | 3D Solid Models |
| Pavement Markings | Corridor, String or Feature Modeling | 3D Line Strings |
| Curb & Gutters | Corridor, String or Feature Modeling | 3D Line String (flow line) 3D Line String (top of curb) |
| Retaining Walls | Corridor, String or Feature Modeling | 3D Line Strings |
The following table details design features to be completed by milestone along with the optimal data density:
| Feature | Preliminary Design | Plan-In-Hand Design | Final Design |
|---|---|---|---|
| Roadways Top of Surface | |||
| Roadways Interim Surface | |||
| Roadways Subgrade Surface | |||
| Roadways (Data Density) | 10 ft [2.5 m] in curves 25 ft [5 m] in tangent |
10 ft [2.5 m] in curves 25 ft [5 m] in tangent |
1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
| Side Slopes | 10 ft [2.5 m] in curves 25 ft [5 m] in tangent |
10 ft [2.5 m] in curves 25 ft [5 m] in tangent |
1 ft [0.25 m] curves 5 ft [1 m] in tangent |
| Gore Areas | 10 ft [2.5 m] | 10 ft [2.5 m] | 1 ft [0.25 m] |
| Intersections & Interchanges | 10 ft [2.5 m] Intersections 25 ft [5 m] Interchanges |
10 ft [2.5 m] Intersections 25 ft [5 m] Interchanges |
1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
| Medians & Cross-overs | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
||
| Sidewalks & Bike Paths | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
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| Lane Width Transitions | 10 ft [2.5 m] | 10 ft [2.5 m] | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
| Headwall Grading | 1 ft [0.25 m] | ||
| Guardrail Berm Transitions | 1 ft [0.25 m] | ||
| Benching Transitions | 1 ft [0.25 m] | ||
| Bridge Abutments | 1 ft [0.25 m] | ||
| Bridge Substructures | 1 ft [0.25 m] | ||
| Bridge Superstructures & Decks | 1 ft [0.25 m] | ||
| Stormwater Ponds, Ditches & Swales | 25 ft [5 m] | 25 ft [5 m] | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
| Drainage and Utility Pipes | |||
| Drainage and Utility Structures | |||
| Pavement Markings | 25 ft [5 m] | 25 ft [5 m] | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
| Curb & Gutter | 25 ft [5 m] | 25 ft [5 m] | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
| Retaining Walls | 10 ft [2.5 m] | 10 ft [2.5 m] | 1 ft [0.25 m] in curves 5 ft [1 m] in tangent |
Note: The maximum recommended intervals are shown; density may be lowered based on the Project Manager's discretion.
Last updated: Wednesday, March 13, 2024