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Workflow Processes:

• Retrofit Centerline Profile

  The centerline profile is the primary grading feature for the urban roadway workflow. To set the elevation and grades for the proposed profile, you must take into consideration the constraints for your project. As is typical in urban roadways, the design profile needs to fit within a very specific elevation range to meet the minimum and maximum grading requirements for the project.
  To determine the allowable elevation range, reverse grade assemblies are needed to solve the centerline profile from “outward-in”. To do this you need to know where the variability is in the design, then build out an assembly that models the minimum and maximum allowable grades. These reverse grade assemblies, will then be applied to the construction limits on both sides of the road, using a setup corridor.
  The setup corridor is needed to create 4 setup surfaces; Left elevation maximum, Left elevation minimum, Right elevation maximum, and Right elevation minimum. These setup surfaces will be used to sample the centerline profiles, and establish the allowable elevation envelope for the proposed centerline.
  Once the elevation envelope has been defined the proposed profile can be laid out to fit within the design constraints for the urban roadway design. Further refinements can be performed to the proposed centerline to update the overall grading model for the project. Making adjustments to the proposed profile will require some downstream refinements to the secondary grading features.
  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Retrofit Centerline Profile – Overview

• Retrofit Curb Return Profiles

  The curb return profiles are secondary grading features for the urban roadway design. These profiles blend the side road edge of pavement into the primary road edge of pavement. The curb return alignments and profiles define the baselines used to grade the curb return regions in the intersections. In most urban designs, the lane cross slopes in the curb return regions need to meet the minimum grading requirements, but not exceed the maximum grading requirements.
  To determine the allowable elevation range, a reverse grade assembly is needed. This assembly will solve the curb return profile by grading “outward-in”. To do this you’ll need to create an assembly that follows the curb return baseline, but attaches the lane components to the side road centerline and primary road edge of travel way, alignment and profile. The lane width will need to be controlled by targeting the curb return alignment. This reverse grade assembly will need to include 2 user-defined inputs to model the minimum and maximum lane grades.
  The setup corridor is needed to create 2 setup surfaces; Profile ElevMax and Profile ElevMin. These setup surfaces will be used to sample the curb return profiles, and establish the allowable elevation envelope.
  Once the elevation envelope has been defined the curb return profiles can be laid out to fit within the design constraints. Further refinements can be performed to the proposed curb return profiles to update the intersection grading. Performing adjustments to the curb return profiles will require some downstream refinements to the secondary grading features.
  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Retrofit Curb Return Profiles – Overview

• Grade Curb Cut Profiles

  Curb cut profiles provide an ideal solution for modeling driveways and sidewalk ramps in your urban roadway designs. Curb Cut profiles are used to control the height of the curbs, and allow you to transition from full curb height to lowered curb height easily. Unlike standard “Elevation” profiles, curb cut profiles are based on “Height”, and are added under the centerline parent alignment of the primary road. For a typical undivided roadway design, a curb cut profile is needed for the left and right side of the road.

  To create the curb cut profiles for your urban roadway design, you’ll need to create 2 new profile views; one for the left curb cut and the other for the right curb cut. A new profile will need to be created for each curb cut, and the PVI elevation set to the full curb height. To locate the driveways and curb height transitions, AutoCAD points will be used. Points will be placed at the curb height transitions in the plan view, then projected onto the respective curb cut profile views. Once the points are displayed on the curb cut profiles, PVIs will be inserted at the transitions, and the interior PVIs set to the lowered curb height.

  When the curb cut profiles are targeted in proposed corridor model, the following grading result is expected.

  Grade_Curb_Cut_Profi_001

  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Grade Curb Cut Profiles – Overview

• Create Proposed Corridor

  Creating the proposed corridor model for your urban roadway design will allow you to see how the grading is coming together. This is a good check point for your grading model to be evaluated before continuing forward in the workflow.

  The proposed corridor model introduces the design features into your urban roadway design, including the;
  Design centerline
  Retrofitted design profile
  Full design assemblies
  Partial design assemblies
  Curb return alignments
  Retrofitted curb return profiles
  Curb cut profiles
  Driveway entrances

  Although there is still more work to complete in the urban roadway design you’ll get a sense for how things are coming together and if anything was overlooked or doesn’t look correct. When you’re satisfied with the results you can begin modeling the driveway and sidewalk ramps to ensure they meet your project requirements.

  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Create Proposed Corridor – Overview

• Model Sidewalks and Driveways

  In Urban Roadway designs, terrace and driveway grading have design requirements that limit the minimum and maximum grades. This could mean that both features adhere to the same requirements, or that they have a different requirements.

  To ensure that your design is compliant to the project specifications, you’ll need to fit the sidewalk profiles within the allowable elevation envelope. To define the allowable elevation range, a setup corridor, setup surfaces, and setup assembly will be used. With the elevation envelope defined, you can model the proposed sidewalk profiles to fit within the constraints.

  The current driveway grading for the urban roadway design resembles that displayed in the left image below. After modeling the sidewalks and driveway, they’ll resemble the grading displayed in the right image.

  Model_Sidewalks_and__001

  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Model Sidewalks and Driveways – Overview

• Model Sidewalk Ramps in Intersections

  The sidewalk ramps in an urban roadway design can be graded similar to the sidewalks ramps at driveways. The primary difference is that the grading needs to be performed in the curb return regions. This will require a different set of curb cut profiles, along with proposed sidewalk profiles to ensure the terrace and ramp grading stay within the constraints.

  A new profile view and curb cut profile will need to be created for each curb return region in the urban roadway design. Once the curb cut profiles have been created, another setup corridor will be needed to define the allowable elevation envelope for sidewalk profiles in the curb return regions. This will require four setup surfaces; 2 for the inside edge of sidewalk constraints, and 2 for the ramp constraints. With these elevation envelopes defined, the proposed sidewalk profiles can be modeled within the curb return regions. At the conclusion of this process, a proposed sidewalk profile will be modeled for each curb return region, then added as a target in the proposed corridor model.

  When the sidewalk profiles are modeled in the intersections, the final corridor will show improved grading in the curb return regions. The sidewalk ramps will be well defined and the transition grading in the curb return regions will look more natural.

  Model_Sidewalk_Ramps_002

  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Model Intersection SW Ramps – Overview

• Make Refinements to Corridor Model

  The urban roadway design has been graded, and all requirements addressed. As-is typical in all projects, refinements can be made to achieve the optimal design. This can mean adjusting the proposed design profile, manipulating the driveway and/or ramp locations, and performing basic surface edits to produce a well polished triangulated model.

  In this final process common refinements will be performed to the urban roadway design. The most common edit that you’re likely to make is to the design profile. You may need to adjust the design profile to accommodate changes to the grading control features that were used to define the allowable elevation envelope. Or you made discovered some potential drainage issues that need to be addressed. Regardless of the reasoning for the refinements, editing the design profile will trigger potential updates to the downstream grading features, like the sidewalk and curb return profiles. This process will address the tasks and steps that will help you apply these changes, and update the final corridor model.

  This process will also address updates that you can make to the driveway and sidewalk ramps, and ensure that the updates are reflected in your final corridor model.

  And to get the best grading model for your urban roadway design, a refinement surface can be used to perform some basic surface edits. Refinement surfaces allow you to make minor edits to the proposed grading surface without altering the corridor model.

  REFERENCES:
  To help you understand these concepts better, view the how-to videos on:
  Make Corridor Refinement – Overview