OpenRoads Designer includes several tools to evaluate existing geometric design conditions when projects are programmed for pavement preservation.

These types of projects are usually designated as “resurfacing.” Many other criteria are evaluated and may be included during the design process. Among them are:

• Mill and resurface only, EOP to EOP, no other improvements
• Corrections to horizontal and vertical alignment
• Cross slope or superelevation correction
• Resurface with pedestrian, bicycle, and transit facility improvements (widening)
• Resurface including shoulder pavement
• Resurface adding turn lanes (spot improvements)

This tip is Part 1 in a three-part series to consider when preparing a design as follows:

1. ON YOUR MARK (Alignments, Terrains, and Profiles)
2. GET SET (Templates, Edge Lines, and Corridors)
3. GO (Cross Slope Reports, Superelevation and Vertical Alignment Adjustments)

PART 1 – ON YOUR MARK (Alignments, Terrains, and Profiles)

Prerequisites

These articles are all developed on the following assumption: Existing project data is available from a survey in a design file and contains existing features, existing longitudinal elements, and surface data.

Design Standards

To create an alignment that will evaluate horizontal and vertical design criteria for a given design speed, use OpenRoads Modeling > Geometry > General Tools > Design Standards Toolbar.

Horizontal Baseline

Alignments can be developed from the survey (usually the center or crown points). This alignment needs to be a “Civil Geometry” alignment, with horizontal curves that best fit to match existing points collected along a centerline. This alignment, if imported graphically from the survey points, would result in a series of short tangents with no horizontal curves to determine PC and PT locations to evaluate superelevation transition locations.

One way to develop this alignment is to create long tangent sections using the OpenRoads Modeling > Geometry > Horizontal > Line Between Points that best matches the baseline points on the tangent sections.

Then, add curves using the OpenRoads Modeling > Geometry > Horizontal > Arc Between Elements tool.

Then, create a complex alignment using the OpenRoads Modeling > Geometry > Horizontal > Complex Elements tool.

However, a better tool for this workflow is to use OpenRoads Modeling > Geometry > Horizontal > Define by Best Fit tool…

…with the following setting:

Horizontal Geometry Reports

Whether using the Complex by Elements or the Best Fit Alignment tool, OpenRoads Designer has the following reports built to review the results:

• Horizontal Alignment Review Report (standard Alignment report)
• Station Offset/Base Report (Distance from Survey Points to derived Alignment)

Design Standards

Using the Design Standards Toolbar when creating the Alignment will also provide Errors and Warnings in reference to the design speed for the facility in the Civil Message Center. Curves that do not meet minimum design criteria requirements may need to be further evaluated.

Terrains

As mentioned, data should be available from the survey in a design file containing existing features and existing surface data. Surface data from LiDAR files is very dense (many points) and should be filtered when delivered in a design file. Data collection frequency and accuracy should have been pre-determined for Pavement Preservation projects. It is important to review this data in OpenRoads Design before developing the existing and proposed profiles.

At a minimum, determine the following:

• Where were the longitudinal points collected? Use the Terrain Properties display tools to view the provided terrain data visually.

• What is the distance between the points collected to form the existing surface triangles? Use the Terrain Properties display tools to view the provided terrain data visually and measure the distance between points at triangle vertices.

Existing Profile

Now that the collected survey surface points and breaklines have been evaluated, open the existing surface profile along the derived Horizontal Alignment. Use OpenRoads Modeling > Geometry > Vertical > Quick Profile from Surface tool.

Additionally, use OpenRoads Modeling > Geometry > Vertical > Define Profile By Best Fit tool to create a preliminary vertical alignment along the existing ground.

Use the best fit parameters as shown:

Part 1 Takeaways

1. A well-defined Horizontal Geometry Alignment is necessary to begin an evaluation of the pavement resurfacing.
2. This controlling alignment will be useful to evaluate the design speed criteria, superelevation transitions, cross slope templates, and corridors.
3. It is important to understand the terrain surface delivered from the survey data.
4. Knowing where the breaklines and triangles are formed will give insight into template point controls and corridor intervals. The key is to limit the amount of interpolation during the corridor evaluation and cross slope reporting.