A back to back cantilever, like the TTC, is a single mast structure that supports wires that span over two tracks. However, this structure will be placed in between the two tracks as opposed to either left or right of the tracks.
To place this type of structure there needs to be enough distance in between the two tracks so that equipment can be placed to support the wires. This will be defined by the reach value limits (defined in the design catalogue) of the equipment that is to be attached.
Select the ‘Structure Place’ button from the Linear Draft toolbar and follow the prompts.
At this point you should select one marker. The marker for a back to back cantilever must be located in between two tracks.
After selecting the marker point, accept the choice by right clicking the mouse button. A new prompt will appear asking you to select the rails.
Left and right rail selection will define the orientation of the structure and its annotation box, therefore, the left and right rails must be chosen as if you were looking at the rails in direction of increasing chainage.
In the example below, the chainage is increasing from left to right.
Accept the rail selection by left clicking the mouse button. Once accepted, another prompt will appear asking you to select the right rail.
The right rail will be the rightmost rail of both tracks.
Accept the selection by left clicking the mouse button and the ‘Create Structure’ form will appear.
Choose type 'STC'.
The ‘Create Structure’ form shows a view of the structure and displays boxes that require text to be added as well as displaying engineering values that can be edited.
Once all information has been entered, click 'Confirm' to continue.
The back to back structure will now be placed in your model. The 2D symbology at this point will look similar to that of a regular STC, however, when wires and equipment are added to both sides of the structure, the correct symbology will be displayed (see images below).
Back to back structure without equipment and wires
Back to back structure with equipment and wires
The image below shows the structure in isometric 3D View with the wires and equipment attached.