The extended Version of the Train Line Roundabout Segment. Connect four to get a circle and fill out the 4 empty spots with either a cap or a connector.

You Probably will need unrestricted nudging via the infinite nudge mod to place these (https://ficsit.app/mod/InfiniteNudge)

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Roundabout Connector (https://satisfactory-calculator.com/en/blueprints/index/details/id/7089/name/Roundabout+Connector+%28TL_basic%29)

Roundabout Cap (https://satisfactory-calculator.com/en/blueprints/index/details/id/7088/name/Roundabout+Cap+%28TL%29)

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This is Part of the Retrofuturistic Railway Collection

(https://satisfactory-calculator.com/en/blueprints/index/details/id/6512/name/Retrofuturistic+Railway+Collection) If not specific to this part please leave any comments there.