The Apalon Bridge

Weathering the Apalon Bridge

I have completed the basic layout for the Wampo, Nieke and Sonkrai railway. Before I glue down the track, the bridges have to be built.

The first bridge is the simplest, a two-span deck plate bridge on three concrete piers.

The prototype

The prototype is the Apalon Bridge, about 25 kilometres inside Burma, beyond Three Pagoda Pass, at the 335 km mark from the railhead in Thailand.

John Stewart described it in his book To the River Kawai Two Journeys 1943, 1979, when he visited the bridge on his return journey. At the time it had been abandoned for 35 years, and at that time, appeared to be intact, but “appeared to be freshly painted a dirty shade of red, like coagulated blood. From close up, it is revealed to be nothing but deep rust…” which Stewart says contrasted sharply with the “pervasive greenness of the jungle.”

A photograph shows thick jungle right up to the edge of the pylons on either bank.

Alternate world

This project is more of an “alternative world” – the term taken from speculative fiction than the pure model railroading “freelance.”

In this alternative world, the railway was not abandoned; instead it becomes a mainline route from China and Southeast Asia, as well as traffic between Thailand and Burma as well as the local runs.

However, in the post-war world, there is a minimal budget, and so far, in the period 1946-1947, the maintenance on the hastily built railway is concentrated near the railheads and high traffic areas in Thailand and Burma. The border region that I am modeling is on the list but at the bottom.

So the bridge can be described as “neglected,” and I have weathered it, as it would have been in either world in 1946 or 1947.


A note on construction

In the construction of the Burma Thailand Railway, the wooden bridges, ties (sleepers) and telegraph poles were made from local insect resistant tropical hardwoods, mainly teak. At least during the period of the Second World War, creosote was not available and not used. That means the traditional methods of staining or painting both the wooden trestle and the ties do not apply on this railway.

Teak and other hardwoods were used, usually untreated, for many years after the Second World War across Southeast Asia. Later various forms of anti-insect treatments were used. Today it is more common to use metal and/or concrete for bridges and poles.

The model

The original model is made from two Kato N Scale deck plate bridges with Kato pylons. There is a close resemblance to the original Apalon bridge


The pylons

I came upon a method of creating neglected or decaying concrete purely by accident. I was testing Krylon All Purpose White Primer #41315 on some scrap styrene. The result was a powdery cracked white, not all suitable a primer, but perfect for crumbling or neglected concrete.



First I sprayed the three pylons with Krylon primer. Once it was dry, I applied a wash of Polyscale Concrete, allowed it to dry and then applied two more washes.


The level of the Kwai Noi varies from day to day and sometimes from hour to hour. Flooding is frequent during the rainy season. So how to create flood/mud stains on the pylons? So I tried an experiment, I created a “bath” of artists’ acrylics (raw umber and raw sienna), and mixed it so it actually had a consistency of mud. I left the three pylons outside in the sun, which reduced the bath and left a stain, then transferred the pylons to my work bench, where the remainder of the paint bath evaporated over three days, leaving an authentic looking stain.



After the mud stains were dry, I applied artists’ pastel chalks, first some raw umber followed, in the tropical environment with a bright Phthalo Green, an Olive Green and then a mixture of the two. The final chalks were Black, Mouse Grey and a mixture of both.

The final step was a Krylon matte spray to fix the chalks and remove any sheen.



The track

I have already run experiments with spare Kato Unitrack and Atlas Snaptrack. Both have ties that are too dark to match tropical hardwoods.


As is widely recommended, I coated the rails with oil before each painting step.


What worked best was Krylon Satin Almond spray #42327, which creates a dull grey-brown finish.

The second step was also an experiment. I had successfully tested Home Hardware Teak wood stain on bass and balsa wood prior to building the trestle bridges. (More on that in future posts)



So I brushed the ties with the teak wood stain—and that worked, bringing out the details of the ties and adding a teak-brown tone to the grey from the spray. However, this technique works best on track without a built-in roadbed, since the stain tends to bleed into roadbed. (I am working on a couple of other techniques with the Unitrack)

I then painted individual ties with a variety of washes from Polyscale D&RGW Building Brown, Depot Buff and Mud, adding a smidgen of Box Car Red now and again.

The guardrail and the sides of the rails were painted with Polyscale Rust.
I added a wash of rust on the central walkway.

It was chalk pastels that made all the difference. First was for rust, Caput Mortuum Red, Indian Red, Permanent Red Deep and Raw Umber (and mixtures of those shades). There were several different “shades” of Raw Umber in Curry’s Artists Supplies in Toronto, so I used those to add a general aged appearance. As with the pylons, I used my selection of green to add some hint of the jungle, followed by greys and blacks.

The spans

Kato calls the colour of the deck plate “grey.” But it was actually a grey green that was perfect for my needs since it closely resembled camouflage paints, likely the only paint available in the region at the time anyway.

I used a small sculpturer’s pick to distress parts of the bridge, weakening some of the side rails and poking some small holes, which could have come either from allied strafing or just general wear and tear.

Again I started with wash of Polyscale Rust, followed by a mixture of Rust and Building Brown, but largely left well enough alone.




The main step was a heavy application of pastel chalks, several of mixtures of a rusty orange, followed again by greens and finally by blacks.



Finishing

All the elements were sprayed with Krylon matte finish, to seal the chalks and to remove any remaining plastic shine. I gave the Kato unijoiners a thin wash of concrete, and added a black gantry support in the middle, that I may use for a telegraph pole or just leave as is.

Next step

The next step is the first trestle bridge.