Building a concrete arched bridge
Next, I finished the pier assemblies. I adjusted their height by filing and sanding until they held the center por- tion of the beam bridge at the right height. I then disassembled every- thing, applied sanding sealer to the wood surfaces, let it dry and sanded them again. I repeated the sealing and sanding until the wood grain was no longer visible. Once I was sure the roadway was in its final shape, I glued the balustrade strips to the upper edge of the arch and the styrene deck over the beams. For sharper vertical curves, saw slots on the underside of the balustrade joints would help the assembly bend to fit.
Painting and weathering When I was satisfied with the fit of bridge to the track and approaches, I unscrewed the hardboard roadway and removed the “concrete” portions for air- brushing. I find Floquil Concrete a bit reddish for weathered New England concrete, so I went over it with a light wash of SP Lettering Gray. Since the beams and balustrade were built in a single continuous piece, I simulated ex- pansion joints over the piers with a black fine-point marker.
I’m modeling the transition era, so I began the weathering process by care- fully using a candle to apply soot to the underside of the bridge over the tracks.
Now that the surrounding scenery is mostly finished, I will add an overall light yellow/brown wash and some rust around the expansion joints. As concrete bridges age, the road salt used in the Northeast in winter may make them crumble and rust in places. Sometimes reinforcing steel is exposed. Styrene is not the best material to model this, but you could try chipping bits out with a sharp knife point and abrading areas with a wire wheel or a coarse file. Bridges are often numbered by both the highway department and the rail- road. The B&M numbered the Route 1A overpass “31.92” in paint on both track-facing sides. I will model this by applying white decals over a spot of black paint. Fairly early in the process of adding scenery, I painted my hardboard road black to seal it. For the final road sur- face, I worried that plaster and similar materials might crack as the hardboard flexed. Instead, I used a flexible foam, peel-and-stick two-lane blacktop strip from Faller. This doesn’t look like it will behave well if I ever need to remove it to get at the screws. If I do, I’ll probably cut holes over the screws, then apply man- hole covers or discs cut from left-over material. Consider paint-based paving techniques if you think you will have to disassemble and reassemble a bridge built this way more than once or twice.
Acknowledgment I would like to thank my friend, Alex Bardow, who researched details of the bridge’s history.
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