Overview

Geotechnical data of existing conditions often dictates that designers adjust the thickness of materials to be applied along a corridor by controlling the sublayer profile grade lines independent of the top layer profile grade line.

In the past, a basic method was used to model sublayers and create separate templates with differing vertical offsets from the original top layer to the sublayers. This method required the following steps:

• 1. Create/copy an existing template and edit the vertical offsets to each sublayer.
• 2. Select Modeler > Define Roadway and add additional entries that reflect each of the change points in the subgrade.
• 3. After making any desired changes, rerun the Modeler.

While this method accomplished the task, it could be tedious and did not adequately address rapid change of layer thicknesses.

New Approach

Today a new approach is recommended to better address control of sublayers. First, though, users should be aware of the following rules:

• A transition control point called Centerline exists for each template layer (sublayer) at the centerline of each layer.
• The Centerline transition control name cannot be changed on the centerline point for any layer.
• There is no apparent method to use an independent vertical alignment and attach it to the Centerline transition control on the sublayers.

In addition, to effectively vary the subgrade, users must understand the following criteria:

• Each sublayer must have a unique layer name.
• The literal layer name, including case sensitivity, can actually be used to define the Centerline point for the layer such that for a sublayer named "base", a transition control likewise named "base" can be called out for special layer controls.

Based on these criteria, the following workflow effectively enables users to quickly create and modify sublayers to follow a variable depth layer design:

• 1. Assign a unique name to each sublayer.
• 2. Select Modeler > Define Typical Sections > Transition Control to create new transition controls named exactly the same as the sublayers created in step 1.
• 3. Create new vertical alignments that reflect the depth from the actual profile grade line to the specified sublayers. These vertical alignments names should be the same as the template sublayers, must all be children of the main horizontal alignment that is used during the Roadway Modeler run, and be created as vertical difference type alignments.
  This process is exactly the same as creating a normal vertical alignment; however, the elevations defined along the alignment are plus and minus elevations relative to the top layer profile grade line. In other words, to have the exact same elevation as the centerline profile grade line, the elevation of the sublayer vertical alignment must be zero. To have a depth of .75 feet below the profile grade line at the top layer centerline, the elevation of the vertical must be -.75-feet.
• 4. Select Modeler > Define Roadway > Main > Edit > Horizontal and Vertical Controls to create entries for each sublayer.
• 5. Select each independent Transition Control Name and toggle on the Use Vertical Controls option.
• 6. Set Define By to Vertical Difference.
• 7. Call out the vertical alignment (which is a child of the main centerline horizontal alignment) that matches the sublayer name. Repeat this process for each of the layers to create entries for each sublayer along the corridor.
• 8. Select Modeler > Roadway Modeler and run the newly created roadway definition. Make certain to use the correct horizontal mainline and the vertical alignment that are the profile grade line for the top layer in the modeling run.

See Also

Product TechNotes and FAQs

InRoads Product TechNotes FAQs And Support Video Clips

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

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