How can I connect raceway in one DGN file to raceway in a DGN file attached as a reference so that cable can be routed through these raceways?
Use the Raceway Router tool to draw a Cable Route (also known as an air gap route) in both files so the air gap cable routes meet end-to-end.
In the screenshot above, the red raceway is in DGN file A and the blue raceway is DGN file B. The air gap cable route in DGN file B is highlighted purple.
The Check Routing Connectivity tool will find connectivity between the red and blue raceways with this method.