I received the plans for the layouts last week but unlike Indomitable I couldn't persuade the cat to pose.
The viaduct is a shortened version of the one at Penkridge. Although it is not in the black country it's design is the same principle as a number that were built by the Grand Junction railway through the Black Country and into Birmingham.
It has 5 equal arches standing on Stone pillars with the upper sections and parapets made from a mixture of stone and brick.
First job was to transfer the key dimensions to two MDF sides. The flaring on the pillars was to be added later.
The next image shows a home made attachment to my router. The stud towards the bottom of the ply base is 74mm from the center of the stud to the furthest edge of the routers cutting blade
By drilling a 5mm hole (same size as stud) at the center point the router can rotate around the stud cutting a groove to form the arch (it is a little bigger than required to allow for layers of plasticard and embossed brick plasticard.
Now running the router up a straight edge square to the base I cut out the uprights and a viaduct shape begins to appear.
Johnny Gringo: Since the pillars will need to support the track bed, if we allow 9mm ply for the ply used for the track bed, what is the dimension from the bottom of the pillars to the underside of the track bed.