Road creation failures and preview hints

Road tools communicate through temporary roads, preview lines, highlights, and failure text. If no preview appears, the cursor may not be hitting terrain or a road, a required road may not be selected, or a toolbar may be taking input.

Hint	Possible reason	What to try
Invalid click	The cursor is not hitting usable terrain or road geometry	Zoom in, switch to orthographic view, and click again
No valid road selected	The tool requires an existing selected road	Left-click the road first, then run the tool
Cannot connect this road	The target connection end is unavailable	Use another end or remove the existing connection
Cannot compute transition curve	Angle, distance, or curvature does not fit	Move roads and leave more connection length
Arc angle exceeds 180	The arc is too large or points in the wrong direction	Move the end point or use a larger radius

When a connection fails, move the target point or choose a smoother angle. Re-clicking the same invalid point rarely helps.

Related pages

• Create roads
• Create straight and arc roads
• Extend roads and connect transition curves
• Create interchange ramps
• Minimum radius