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Road Construction Tool

Specify physical construction of road sections


The Road Construction Tool enables you to specify how a section of road is physically constructed. Currently, only standard (on terrain) and bridge types are supported. Tunnels, channels, and abutments are not supported.

You can set the construction type for individual spans along the road. The spans are bounded by construction nodes, which you can insert and move to arbitrary locations along the road reference curve.


You cannot create intersections for bridges. Raised intersections, merges, and splits are not supported.

Open the Road Construction Tool

On the RoadRunner toolbar, click the Road Construction Tool button:

Road Construction Tool button


Create and Modify Construction Types Along a Road

See Span Editing.

Fix Bridges Along a Road

When you create scenes that have bridges, or build scenes that have bridged roads such as by using the Scene Builder Tool, the initially created bridge spans might not form correctly. This example shows how to use the Road Construction Tool to fix such a bridge span in a scene.

Create two intersecting roads by using the Road Plan Tool.

A four-way intersection

Click one of the roads to select it. In the 2D Editor pane, drag the selected road until it is 10 meters above the other road.

A four-way intersection with one road elevated above the other

Create ground terrain around the roads by using the Surface Tool. Move the camera to view the road intersection. The ground attaches to the elevated road, which produces visual artifacts. These visual artifacts occur because the section of road above the other road is not designated as a bridge span.

Intersecting roads with the ground surface attached to the elevated road

To fix the visual artifacts, set the elevated road to be a bridge span. The Surface Tool ignores bridge road spans and does not attach to these spans.

  1. Click the Road Construction Tool button.

  2. Click the elevated road to select it.

  3. In the toolbar on the left, click the Auto Assign Bridges button.

  4. In the Auto Bridge Span window, use the Bridge Span Inflation option to optionally set the length of the bridge span. By default, the tool extends the bridge span by 20 meters on either side of the bottom road. If the remaining road length to the left or right of the road is less the Bridge Span Inflation value, then the bridge span extends to the end of the road. Click OK.

  5. In the Auto Bridge Span Results window, confirm that the road was updated. Remember:

    • If you selected the bottom road, then the tool processes the road but does not create a bridge span.

    • If you previously created a bridge span for the elevated road, then the tool overrides that original bridge span.

    Close the window and view the road that has the created bridge span.

    Intersecting roads with a bridge span formed along the elevated road

With the Road Construction Tool still selected, if you select the middle portion of the road, the Attributes pane shows that this portion has its Construction Span value set to Bridge. The other two portions are set to Standard.

If you have multiple bridges to fix, then you can select multiple roads and use Auto Assign Bridges to fix all of them at once. If you are building scenes by using RoadRunner Scene Builder, then you can use the Auto Detect Bridges option to fix bridges. Using this option is similar to running the Auto Assign Bridges operation on all bridges in a scene. For more details, see Scene Builder Tool.


Construction Span
  • Standard — This portion of the road is at ground level. The surrounding terrain attaches to the sides of the span.

  • Bridge — This portion of the road is elevated. The surrounding terrain is not connected to the sides of the span. A bridge underside mesh is generated along the span.

    When you select this option, the resulting bridge span might be too long. To address this issue, choose one of these options:

    • Use the Road Chop Tool to divide the road into sections. Then, select the section that you want to convert into a bridge and set Construction Span to Bridge.

    • Use the Auto Assign Bridges button to create a bridge span.

MaterialMaterial asset to be used for the sides and underside of the bridge. See Material Assets.
Introduced in R2020a