City Makes High Line Phase Three Official, Signs on the Dotted Line. Today the City and Friends of the High Line announced the acquisition of the third and final portion of the abandoned rail line from CSX, securing once and for all its future as a linear park. The section, which extends into what will become Hudson Yards, will add another half mile to the leafy line. CSX donated the line to the city. Final design work for the third phase is underway. Construction is set to begin later this year.