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A Modern Bridge

My module needed several bridges over a river.  The track had been laid on a strip of luan on top of two inches of pink foam.  Most of the ready made bridges in the stores and internet would require cutting out the section of track, installing the bridge and putting down new track.  Having a realistic bridge design for three closely spaced tracks is a challenge.  Was there another way that would preserve the luan installed under the track?

A little research on the internet showed that, for new construction in the real world, a prestressed concrete bridge would be a realistic choice for this type of application.  A little more searching found a web site with engineering drawings and specifications for modern railroad bridges.  The drawing for a prestressed concrete bridge was copied to PhotoShop, reduced to N-scale, and printed to provide a bridge template. 

The luan under the roadbed become part of the “prestressed beams.”  Using a router, a three foot piece of poplar was cut into the indicated shape to provide the bridge sides.  Poplar was selected because it is a closed grain hardwood, fairly easy to work, and does not spinter easily.  Abutments were made from 0.25 thick pieces of poplar. 

To get a good concrete look, all pieces were carefully sanded to get out any grain marks and spray painted with three coats of latex paint.  A black wash, one part black to 8 parts water, was over-sprayed to give the “rough” look of concrete.  The parts for one of the smaller bridges is shown at left.  The abutments were installed on the module, the sides glued in place and ballast added.

Here is the result: