What was the pull factor that started the building of the trans-siberian railway? ?

At the end of the 19th century, Siberia had problems to achieve its development, due to its bad transport and bad communications, as well as all of Russia. In addition to the Siberian Route, there were no efficient roads for transport on wheels, so the rivers were used for transport, and when the winter froze the roads, passengers and goods traveled on horse-drawn sleds, using the same frozen rivers . The solution to these serious problems was to build a train that would connect all of Russia to Siberia. Many projects were presented, and Tsar Alexander III supported and promoted the construction of the railway, which began in 1891 and was built at the same time in several geographical areas, including China, which would also connect the East with Europe.