The collection of all corridors in a document are held in the AeccRoadwayDocument.Corridors property.
The following sample displays the name and the largest possible triangle side of every corridor in a document:
Dim oCorridors As AeccCorridors Set oCorridors = oRoadwayDocument.Corridors Dim oCorridor As AeccCorridor For Each oCorridor In oCorridors Debug.Print "Corridor: " & oCorridor.Name Debug.Print oCorridor.MaximumTriangleSideLength Next