10 September 2014

A Bridge So Far...

or.. Bridge over the Triple Track (for that is what this will be)

Recently, I was very pleased to be given my first ever modelling commission following the sale of a couple of double track tunnel portals that I had no room for. There was nothing wrong with them - it's just that as I'd made my track layout 4 wide, I simply had nowhere for them to go and so I playfully offered them for sale on a model rail forum, and they were duly snapped up.

That same buyer then, some time later, asked me if I could build him a plate girder bridge to traverse 3 three lines acting as a scenic break at the start of his storage area, and I jumped at the chance (I've always wanted to build a plate girder bridge).

Much to-ing and fro-ing was done with measurements and photographs via email and eventually I arrived at a scale plan of the track area so I could work out the span width. Because it's going on a slight curve, I figured that a slightly skewed bridge would be the order of the day.

Even though the bridge is a scenic break, the storage area is also scenic, so I was tasked with making both sides. Strangely enough - the first part of this build was the 4 wing walls which I already had a drawing for.  These were all hand-scribed onto 3mm foamex and then followed the abutments - again from 3mm foamex.

I decided to add a little extra detail on the corners and I did this with some 20thou plasticard, cut into 8mm strips and stuck to the foamex with a generous dousing of MEK. Once set, I marked in where the course lined up from the scribed stonework, and then cut out the excess. A generous dousing of MEK at the corner join helped weld the two strips together and again, once fully set, I scratched in the courses with a sharp scalpel. In the end, I think above and beyond the call of duty for the budget, but I believe in quality and I think the extra detail makes the difference.

You should be able to see here the corner detail here of the raw foamex and plasticard quoins. This is a later picture in the build progress after I'd constructed the girder deck
Once the stonework courses had all painstakingly been scribed, using my trusted method of set square and dart tip, I then worked up the texture of the stones, again using the dart tip, but instead of scratching in lines as such, I pressed the edge in to emboss detail.

I won't say this method is very quick, but it's very therapeutic and I found myself picking up a buttress or two to continue scribing whilst waiting for the kettle to boil - any excuse to be in the kitchen!

The next step was the plate girder - which I was quite excited about - made from Wills' excellent Vari Girder pack. The panels are crisply moulded and once cut off the fret, fit together nicely.
I'd found a reference to their measurements online for my drawing and once I'd got them out of the pack, I found that with 12 panels per span was just the ticket. It's a good job I'd bought two packs as each span took 24 panels.

I then set aide the completed spans to form the bridge deck. Now my customer's budget didn't run to fine scale representation of under bridge detailing, so I decided to represent a passing notion of the supporting girders by fixing on 6mm wide strips of 30thou to the underside. The edges of this would then glue to the edges of the vari girders to form a strong plastic weld.

Picture the scene - it's now 11.30pm and I'm getting tired and thinking of bed. I'm very pleased with my ingenious cutting of the strips (allowing a slight recess for the edges of the vari girder panels to butt up to, and so it comes to test fitting the deck before gluing onto the girders. What's this? Oh you fool! you've only glued them on to the wrong side (being a skewed deck, it matters!)

A resigned sigh was followed by careful stripping off and flipping over to start again…

The "completed" structure - and now it's time for bed!

As morning dawned, I found that the sides of the deck had dried out of true, but I think I've fixed that with a bit of gentle persuasion…

And so, to the primer stage:

At this point, the plate girders hadn't been primed. But they have now...

Hopefully the next blog post will be the finished thing prior to despatch.

I'm going to have to make myself one next! :)


  1. A lovely job, Lee. Clean and sharp and beautifully scribed. Your customer got his money's worth there, I reckon. I do like your method of embossing the foamex as opposed to my scratching the surface of the stones and I'll wager it's more fun too! I find that there is something really nice about the bare foamex when it's been scribed, yours looks very nice with those angles. I hope we get to see some photos of the bridge in position!

    1. Hi Iain - I know what you mean about the bare foamex - it's such a great material to work with. I think we will get to see some in-situ shots as my customer has just sent me some shots of the model's eventual location and he's got some very nice trackwork down and some great looking locos too!

  2. Hi Lee, well you won't have to spend money on advertising your services - your work speaks for itself! I really like this bridge, it's not only visually interesting but has just that right mix of mass and neat detail to make it look like a real railway structure. You'll be running our of business soon! :-)

  3. Hi Mikkel - thanks for that. I must say I've enjoyed building something for someone else.

  4. Congratulations on your first commission Lee :-)

    That's a very nice, neatly made model you have built there, I really must give 'foamtex' and your methods a try.

    I did wonder if perhaps a couple more flange stiffening plates should be applied to both the top and bottom of the girders due to the length of the span. But I suppose that would depend on the load that the bridge would be expected to support?

    1. Thank you Geoff.

      It's a valid point you make there, but as it's only a single road farm track that's going over it (yep, it is pretty serious engineering for a farm track) I think I can get away with it ;)

    2. There's a very good prototype for a massive girder bridge carrying very little near me at Minfford. A large span girder bridge for bats and the occasional badger on the FR!

    3. Hehe - that's what massive Victorian engineering is for!

  5. Lee,

    Congratulations on your entrance to the commercial world...And what an entrance!!!

    Absolutely superb in every aspect and a very nice taste of what we can expect as business surely will ramp up!

    Well done and we look forward to the next instalment.


    Rod Kelly