Railroad track

Railroad track
Railroad track: railway rack made of parallel steel rails laid on wooden ties.
Rail: set of steel bars placed end to end in two parallel lines.
Fishplate bolt: piece of steel with a head at one end and threaded at the other, used in conjunction with a nut to connect the rails of a railway track.
Spike: curved piece of metal used to attach the base plate pad to the rail.
Tie: wooden plank laid perpendicular to and beneath the rails.
Tie plate: piece of metal that supports the rail.
Nut: piece of metal that holds a bolt in place.
Expansion space: space left between the rails to allow expansion when the temperature rises.

Photo :

EN : Bridge structure
FR : Structure de pont
ES : Estructura del puente

Bridge 
          structure

A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs of bridges vary depending on the function of the bridge and the nature of the terrain where the bridge is to be constructed.