Tag Archives: road bridge

Building Bridges

Where was I? Oh yes. I spent days, yes, days, applying stonework to my MDF bridge armature using my DAS clay technique.

In the end it looks great. A bit of a caricature of vernacular stonework if I’m honest, but as the scale gets smaller a bit of emphasis helps.

Okay. I know the arch is asymmetrical. But there’s a story behind it. At least, there will be…

A few weeks ago I was in Home Depot and I noticed in the shaky can section they had a textured “granite” spray, so this was a chance to try it out. After masking out the roadway and whitewashed walls and wooden rubbing strip I spent a happy moment in the garage carefully priming the structure. This paint goes on really thick, so take your time with several thin coats letting it dry in between

In the event it was pretty cold there, so the paint had a problem “drying” in the garage, so in the end I brought it indoors, where Mrs Hill and I spent a heady night with the bridge perched above a heating vent.

Once again, the texture was possibly a bit much, but as I started to render the surface back it started to look pretty good. I also started to pick out individual blocks in various shades of grey. Just a fine brush and a palette of black and warm white with the occasional bit of pink. Yes. Granite has pink in it. I also treated a couple of areas with a mossy green colour under ledges and in corners although these aren’t evident in the images, but will pull out when I apply the final matt varnish coat… I hope.

Initially I used dropper bottles to drip various mixtures of grey/cream to represent mortar between the stones. Moisten with “wet-water” first. If you dilute your mixtures correctly, at first the courses look pretty garish, but as the paint dries it cuts back. If I found any particular spot was looking a bit too much I used a torn edge of paper towel to soak up the excess. Once dry use a stiff dry-brush to cut it back further if required

You’ll notice that above the tracks I’ve tried to imply soot and grime from the steam and exhaust of the engines. Also, on the right I’ve started to suggest the cornerstones have been painted white for safety reasons. There will be a platform continuing under the bridge. I’m also going to place a light in there for effect – and the convenience of people waiting for a train.

Tailgating? What’s that?

And this is where I’m at. A bit of a local traffic jam on the bridge where the new NHS midwife is on her way to a prenatal home visit. Obviously, she’s new to Dartmoor from the Big City or she wouldn’t have a Morris Minor convertible. Just wait for the first real downpour or blizzard… Meanwhile the RAC guy is on the rounds, fixing the “Do Not Feed The Ponies” signs and rescuing damsels in distress.

So now the bridge awaits the application of  weathering powders and a bit of plant life sprouting from appropriate places before blending into the landscape.

The road surface – actually one of the most difficult modelling challenges – is also awaiting treatment a la Kathy Millatt, while the wooden rubbing strip is going to be aged using another fine product, MicroMark Age-It-Easy.

Now. Where Was I?

Well, summer’s over. We’ve even seen a surprise snowstorm here in New Jersey. And my sister actually lives on Dartmoor tells me they’ve had snow there as well.

So it’s back to work on the Boltorr branch. 

I’m currently working on the road bridge which forms the scenic break at the northern end of the layout. It’s built using a structure of 2mm MDF, and stonework of chips of DAS modelling clay. 

The bridge ready for trimming
The bridge ready for trimming and rendering

All stonework is finished except for some trimming and my next stage will be representing the road, actually one of the most difficult exercises in modelling. I also have some etched drain covers and rain grills to add some detail. I just have to figure how to give the road a hint of camber.

The bridge will then be ready for painting and rendering.

Devon General 46 squeezes across
Devon General 46 squeezes across

My priority now will be to get the basic landform settled so I can actually lay some track. Initially the layout will be DC, but I’m wiring it so it will be easy to convert to DCC at some point. 

Bridge Building: I

Time to think about the road bridge over the tracks. This is going to serve as a scenic break so that the layout appears to run north-east all the way to Exeter.

I’m going back to the method I used for the tunnel portal to the south. For the basic structure I’ve used 2mm MDF. This is quite hard to source here. In the end I got mine from Am@zon, but it actually shipped from Sweden.

2mm MDF and foam-board
2mm MDF and foam-board
Aligning and levelling the bridge
Aligning and levelling the bridge

I made a template for the stonework of the bridge as described in another article and cut the front and the back of the bridge together so they would – hopefully – be identical. I used foam-board for the road plane and as internal braces to stabilise the structure. The whole lot is joined together with PVA glue.
The bridge in situ. There is space on the right for the platform to continue under the bridge
The bridge in situ. There is space on the right for the platform to continue under the bridge

I’ve applied foam-board and styrene strip to represent buttresses and some masonry embellishment. Only the layout side is going to be treated since the other side of the bridge won’t be visible.

Next step is to install the bridge liner and roof.

Build a Road-over bridge

Impermanent Ways - volume 6... Noodle Books: 978-1-906419-99-8
Impermanent Ways – volume 6… Noodle Books: 978-1-906419-99-8
I had hoped to find a laser-cut bridge kit somewhere on the interwebs, but nothing looked quite right.

My DAS chip method is tedious, but it looks so good. I think I’m committed to it now, if only to maintain a “look” across the layout.

I looked around Google images for a bridge to base Boltorr’s on, but didn’t find an example which fitted Dumnonia’s needs better than the one illustrated on the cover of “Impermanent Ways v6“. So I’m not certain the rights’ issues involved here, but buy the book! The whole series is a huge resource if you model in this area.

The real issue when building a model bridge which never actually existed, is getting the arch right.

The image is on the oblique and needs to be adjusted
The image is on the oblique and needs to be adjusted

The photo of the bridge on the cover is on the oblique, so I used an image editor to square the perspective and match an ellipse to the arch.
I adjusted the perspective then constructed an ellipse to match the arch
I adjusted the perspective then constructed an ellipse to match the arch

I then reduced the image to black & white to produce a template. I’ll jiggle with the width of the bridge and the chord of the road deck to fit my location.

In Boltorr’s case, this means spanning the branchline, a siding and possibly an extension of the platform under the bridge. I will also have to adjust to accommodate the road level above.

I reduced the image to b/w to use as a template
I reduced the image to b/w to use as a template

The northern exit starts its evolution
The northern exit starts its evolution

At this point, I’m not considering a hi-tech solution. It’ll be a combination of printer settings and a pair of scissors.

For construction I’m going back to 2mm MDF with appliqué stonework courtesy of DAS. This provides the most stable foundation.

Boltorr Dam and the rail bridge abutments were built using foam-board which tends to take a form of its own if it possibly can. This is not necessarily a bad thing, but for engineering elements it’s a problem. MDF resists the urge to distort far better.