One final tangent curve needs to be added to the sketch before you can connect it to the existing casing and add the feature. In this example you use the Tangent Curve tool to add a curve with a chord length of 12 and a delta angle of 120.

To finish the sketch and create the feature so it is connected to the existing casing, you need to snap the last point of the sketch to the endpoint of the existing road casing.

Because snapping to the endpoints of the line features was enabled, you can move the pointer to the endpoint of the existing road casing and it will snap to it.

Double-clicking adds the last vertex to the edit sketch and finishes the sketch to create the feature.