The Himalayan Mountains, Andes and the Alps would be cases in point.
With globalisation and trade liberalisation, the economic viability of constructing of these railways is improving.
[1] In 2009, a railway was proposed to link Lashio, Myanmar and Jiegao, China and which also crosses the Himalaya Mountains.
The proposed trans-Himalayan railway from Pakistan to China via the Khunjerab Pass could count as a transcontinental railroad due to the size of the mountains in the way.
This line would be approximately 1,100 kilometres (680 mi) long.