Yes, on the dead bodies of those poor souls/slaves who built it! It is estimated for every mile of track laid, two people died. The trans-Siberian railway is (I believe) over 5,000 miles long. Terrible, just terrible, the amount of human agony and suffering Stalin inflected upon his own people all under the “glorious/infamous” banner of Communism, but as "Uncle Joe" said;
"You kill one man and it is a ‘tragedy’; you kill a million men and it is merely a statistic."