Add a free transition-curve-transition group between two elements.
The type of transitions created (simple vs. compound) depends on the types of elements you attach it to. When the attachment elements (1, 2) are edited, the transition lengths (3, 4) and curve radius (5) do not change. The attachment points and the curve length adjust to accommodate edits to the attachment elements.
The Transition-Curve-Transition command is similar to the command that adds a free curve by radius between two elements. However, this command adds a transition transition in and a transition transition out. The curve group for this command is the same as the automatic curve group that is created when you use the Straight-Straight command. However, with this command you can create a TCT curve group between curves.
You cannot grip edit the transition-curve-transition curve group, but you can edit the elements to which the TCT group is attached. Make edits to the transition or curve parameters in the Alignment Layout Parameters window or the Alignment Entities vista.
TCT curve group between two straights
A TCT curve group placed between two straights creates two simple transitions.
TCT curve group between a curve and a straight
A TCT curve group placed between a straight and a curve results in the simple transition attached to the straight and a compound transition attached to the curve.
TCT curve group between two curves
A TCT curve group placed between two curves creates two compound transitions. The TCT curve group should only be placed in a configuration where the attachment to either curve forms a compound curve-curve situation.