First, Brienzer Rothorn rack railway doesnt operate in winter at all.
Unfortunately, all swiss “premium” mountains are super pricy to visit.
If its just about steam train, there is more suitable solutions 
(But not in Switzerland..) In east germany there is a lot still existing, which you could also visit by 49 euro ticket.
Touching Switzerland: have a look into Rhibähnli (google Bahn Internationale Rhein Regulierung). To visit that one, I recommend Bodensee Vorarlberg Freizeitkarte. Have a look into that one, especially to know the other benefits.
To make nice mountains affordable, have a look into saver day cards issued by SBB. in that one, Rigi, Stanserhorn (the one with the famous cabrio cabin) and Rochers de Naye are included. As well as less public transport in whole countries including busses and most passenger boat lines. For the validity google the keyword “GA Geltungsbereich”
Only disadvantage, you shoild buy it already know since the prices will get higher the closer to the date
I will be going to Switzerland in the summer (might re-visit for winter again), hence for this trip, I am really interested in the Brienz Rothorn Bahn as I think going on winter won’t have the same scenery.
But it’s pretty pricey (return trip is 96 CHF, is it not covered by interrail, not even a discount?), is it really worth it? The cable car to the top of Zermatt is almost similar price even. Any suggestion or maybe there are other more affordable steam trains for interrail holders?
Addition: is it possible to get one way up, then hike down? or would that be too much of a hike
Thank you!
The trip with the Brienz Rothorn Bahn is a great one. It's not just because it's steam hauled, it's because of the scenery. So it's certainly worth it.
It's just operating June 8th to October 20th.
It's possible to hike down. But it takes about 5 hours and it's not "walking down" (e.g. with normal shoes).
You do get 20% if staying in Brienz. There are also regional passes that include the Brienz Rothorn Bahn and many others if you are staying a few days in that area and doing some more trips.
Thank you so much!! Will try to consider it as it’s pretty pricey and we need to decide whether to take that or to go to Zermatt to take the cable car, as both options cost more or less the same...
