If you know the name of this track system, please post a comment or email me.
A sort of track "funnel" at viaduct entrance.
This system is meant to put back on track any derailed train car at the entrance of the viaduct (railroad bridge). On the viaduct there are two pairs of guard rails, so that in case a train car derails while on the bridge, it will likely still be on rails, to prevent a deadly accident.
Railroad viaduct over the rio toro near Salta (Argentina).
This train line between Salta and San Antonio de los Cobres is sometimes called "Tren a las nubes". For more information, read en.wikipedia.org/wiki/Tren_a_las_Nubes
Photos taken in Argentina in Februaty and March 2010.