Virgin Trains USA, formerly Brightline, says it has began construction on the company’s $4 billion passenger-rail line between Orlando and southern Florida.

Contractors for Phase 2 are Hubbard Construction Co., Wharton-Smith Inc., The Middlesex Corp., Granite Construction Inc. and HSR Constructors.

The rail line’s second expansion phase involves 170 miles of new track running to the completed intermodal facility located in the new South Terminal at Orlando International Airport.

Phase 2 construction will be conducted in four zones between Orlando and West Palm Beach. Work on the first two zones began May 21 near Virgin Trains’ maintenance facility at the airport. Full scale construction of the second two zones is imminent, Virgin officials said in a news release..

The construction project will include the laying of 490,000 ties and transporting 2.35 million tons of granite and limestone by 20,000 rail cars. About 2 million spikes and bolts will be hammered into place over the next 36 months.

HSR is a joint venture of three rail and transit contractors: Herzog, Stacy and Witbeck and RailWorks Corp.

“Connecting Central and South Florida will bring thousands of jobs today and by modernizing infrastructure, we will strengthen Florida’s economy for decades,” Virgin Trains USA president Patrick Goddard said in a statement. “For a project of this scope and magnitude, a world-class construction team has been assembled to undertake this tremendous assignment and we congratulate them helping us make history.”

Virgin Trains currently operates passenger-rail service between Miami and West Palm Beach.