The railway that runs from Seattle up to Everett and either on to Vancouver or east across the Cascades crosses a bridge that is just outside the locks at Ballard.  The bridge is a bascule bridge and, since there is quite regular boat traffic including sailing boats with high masts, it is frequently opened.  The low winter light does a nice job of illuminating the underside of the deck of the bridge when it is open.  I was more interested in the shapes at the end of the bridge where the rails end.  They are clearly shaped to interlock with the opposite rails on the bridge approach and also to have a shape which allows the wheels to smoothly pass over without some sudden impact forces.  As they stand up in the air, they strike me as rather fascinating.