One of the world's most ambitious railway expansion projects, a $4.5 billion line linking regions crossed by Russia's Siberian Railroad, took a step forward Thursday with the announcement that the four participating countries would form a joint venture company to continue preliminary studies initiated last year.

The agreement to form a joint venture was reached at a meeting of high-ranking Austrian, Russian, Ukrainian, and Slovakian railway officials in the Russian Black Sea resort city of Kochi.

Russia's broad-gauge will be used in the expansion from Konice in Slovakia to the Austrian capital, Vienna. Current technology enables a smooth gauge change.

Plans for the line were unveiled in April 2008 when the railways signed a protocol to initiate pre-project studies.

The goal is to make the rail systems more competitive against sea and road transport.