Place props and extrusions along road
The Prop Span Tool is used to place props and extrusions along a road.
Unlike the Prop Curve Tool, props placed along spans remain anchored to the road and update automatically when the road is moved.
On the RoadRunner toolbar, click the Prop Span Tool button:
See Span Editing.
Only a single prop asset can be assigned to a given span (although you can split a span into two spans). To assign two prop assets (for example, a guardrail on the edge of the road and a row of trees behind it), you can work around this limitation by assigning props to a span curve on a different lane, and then adjusting the Offset value to shift the props.
For example, you can assign a tree asset to the inner sidewalk curve, and then increase the Offset value to push the trees outward past the outer edge of the sidewalk.