an ÖBB 1099 class electric with a passenger train on the Saugraben Viaduct of the Mariazellerbahn, Austria

The viaduct with its stone pillars spans 113 meters and stands 37 meters high, making it the largest and highest on the line. 

The 760 mm gauge (2'6") 91 km long mountain line from St Pölten was opened over 1898-1907 and electrified in 1911. Originally designated as the NÖLB Series E, the 16 electric locomotives were manufactured by Krauß & Co. in Linz (mechanical components) and Siemens-Schuckert-Werke (electrical equipment) for the Niederösterreichische Landesbahnen. Designated as Serie 1099 after 1945 they remained for over a century, being retired officially in 2013.

Specifications: C-C type, 49 tonnes, 10.9 meters long over buffers, 50 km/h maximum speed, power output: 320 kW or 429 hp (continuous) / 420 kW or 563 hp (one hour), overhead system: 6.5 kV AC, 25 Hz.

Pic from 1962.