Westbahn is a private railway company that has run trains between Salzburg and Vienna on the Westbahn since 2011, at hourly intervals. From what I have seen, they are always well used, given the competitive fares. The rolling stock is built by Stadler, Kiss type (https://en.wikipedia.org/wiki/Stadler_KISS): double-deck trains with a top speed of 200 km/h, which run on the double-track high-speed sections of the line. Excellent service.
Photographed on 21/06/2019 at Prinzersdorf (St. Pölten District, Lower Austria, Austria).