The Mariazellerbahn stretches from the railway station of St. Pölten in Lower Austria to Mariazell in Styria. The 84 km long main line is electrified, the branch line to Mank is not.

The first section between St. Pölten and Kirchberg and the branch line were built in 1898. The mountain line was ready in 1906, it was opened for the passenger traffic in 1907. The main line was electrified with 6,5 kV 25 Hz single phase AC in 1911, by 1914, 16 electric locomotives were built (today's class 1099), their major part is still in service. The class 1099 locos often haul long trains, coupled in double units. In the passenger traffic, the class 4090 electric trainsets and the class 5090 motor cars are helping as well - latter vehicles mostly on the non-electrified branch line.

The future of the Mariazellerbahn is unsure. According to a conception, the valley line would be rebuilt in standard gauge. This would mean the end for the direct transfer connection of  the remaining mountain line to the Westbahn international railway line