As of Update 8, you can use the Place Road tool to continue an existing road.

1. Select Road. The alignment is highlighted and sprites representing its cardinal points are displayed.
2. Hover over the Point of Beginning (POB) or Point of Ending (POE) of the roadway. Right-click to display the new Add PIs menu.
3. The user can then add multiple PIs with curves (and spirals, if defined) based on the roadway's design speed.