I have played Russian Railroads 3 times. And all three times the games were won by players who never scored on any track higher than gray. I tried all Trans Siberian the first game and almost won. (I think I might have if I hadn't spent the game answering questions and clarifying things for the other players.) And the next 2 games I tried combos with getting some brown and beige mixed with other lines and industry. I seem to be obsessed with the impressive power of the beige and white and want it to work but can they win? If not I would be disappointed.
I have won (and lost) with every type of strategy. It is very important not to loose your focus; otherwise you end with subpar result. I have seen 140+ points scored on the Transsib alone in round 7 of the game
Whether you go for any particular strategy or not should be highly dependent on what engineers are in play and what other players are doing (and of course player count). Getting your timing right is also critical to doing well in any strategy. There are a lot of ways to muck up a strategy if you're not careful.
The Trans Siberian strategy is very powerful and scores a ton on the last turn, but it's one of the easier strategies to mess up in my opinion. If you dawdle or get distracted then you're not going to score enough on that last turn.