This is the dialog where you define the free vehicle clearance boxes for your tunnel.
First, you must specify the name and the stationing/chainage interval for the free space. The name is just for making it easy to recognize the free space specification later.
Different from most other tunnel structure elements, free space can be overlapping. This means that several free space boxes can be defined at the same chainage number.
You must specify the Surface Edge Number for the left and right connection points for the free space and define the Height of the free space in meters. The height is calculated normal to the road surface individually for the left and right sides of the free space box.
Click OK to save the data from this dialog to the tunnel model shown in the Define Tunnel Profile Geometry dialog and close the dialog.
Click Apply to just save the data from this dialog to the tunnel model without closing the dialog.
Click Close to shut down this dialog without saving the data.