Before I can finalise the height of the backscene at the point where it curves around the front of the layout, I need to work out the contour of the landscape in this area. During the planning stage of the layout http://www.rmweb.co.uk/community/index.php?/blog/1131/entry-9648-mock-up-completed/, I decided to have a twin arch road bridge that would act as a view blocker between the off stage area and the main layout. The height of this bridge will dictate the profile of the land around it, so before I can progress any further with the layout, I need to tackle it's construction.

I looked on the internet for suitable prototypes, this link from Miss Prism was very inspirational.

http://www.derekhayward.co.uk/EastGrinsteadHighLevelLine/Hartfield/20389229_8HCJW6#!i=1613519584&k=2qrHw3C&lb=1&s=A

I regularly walk the old track bed of the Cardiff Railway http://en.wikipedia.org/wiki/Cardiff_Railway, It's one my dog Henry's favourite walks. Between Coryton and Tongwynlais a very nice five arch bridge crosses the line and this bridge also helped provide prototype inspiration for my model. I took a number of pictures of the bridge, some of which I've included below.

5 arch bridge crossing the old Cardiff Railway between Coryton & Tongwynlais

Armed with all this information, I made a start on the model by drawing out a paper template to check the proportions of the bridge and the position of the arches relative to the track work on the layout.

Paper template

Once I was happy with the paper template these dimensions were transferred onto a sheet of 40 thou Plasticard. South Eastern Finecast do very useful sheets of embossed brick arches and abutments, so I decided to use these to represent the brickwork.

Arches inlaid and horizontal brickwork in position

Arches cut out & top curved profile cut

The horizontal courses of brickwork stop just above the brick aches and are then laid to follow the curve of the bridge parapet. In order to represent this, the brick plastic card sheet was cut back to expose the underlying plain 40 thou sheet.

Horizontal brickwork cut back to allow curved brick work to be added

Once the brickwork had been cut back, brick sheet was cut into 3 brick high strips and these were laid to follow the curved profile. I decided that a couple of raised brick string courses would look good, so these were built up in situ on top of the brickwork.

Curved brick courses being laid

Finished inlaid curved brickwork and raised string courses

Completed bridge side

Once this first side was completed, I used it as a template to draw around to make the other side profile of the bridge. I needed to work out how wide the roadway over the bridge would most likely be, so I counted the bricks across the width of one of the abutments in my photos. The picture showed that the prototype bridge was 19 bricks wide, so assuming a brick was 9 inches long then the bridge was 171 inches, or 14 foot 3 inches wide. This equates to 99.75 mm in 7mm scale, so I cut some width spacers 100mm wide, which was close enough for me! These spacers were glued in position between the sides and allowed to dry for 24 hours.

Spacers in situ

Other side added

Once everything had set in position I placed the bridge onto the layout to check that I hadn't miscalculated any clearances anywhere! I had to cut some of the roadway to follow the curve on the backscene, but that apart it seems to fit in quite well.

Bridge in position on layout

I've still got to form the underside of the arches, the side walls under the bridge, the piers either end of the bridge and the retaining wall abutments, but I'll save all that for the next blog entry!

Until next time.

Best wishes to all!