Although not required, the preferred directions tool is highly recommended. It will allow the use of the green and blue routing types when operating the route. This is because they rely on knowing which direction is the best to get between any two signals.
This tool is available from the Mode menu, and the route must be saved and have a successful completion to use the tool. It works by selecting multiple track elements, and the preferred direction will run along the selected route. Confirm your route using the add button in the menu.