Amtrak has money to expand, but it doesn’t own the railroad tracks. A stalled effort along the Gulf Coast is a test of its ability to grow.

Months after Washington approved billions to significantly expand Amtrak’s footprint across the country, an early attempt at growth has reached an impasse in a test case that could define the American rail network for a generation.

The escalating clash is playing out on the Gulf Coast, where Amtrak wants to restore service 17 years after Hurricane Katrina flooded the region’s rail infrastructure. Amid fanfare over federal money as a president nicknamed “Amtrak Joe” watches from the White House, the passenger rail and the freight railroads that control the tracks are in mediation to resolve disputes over Amtrak’s proposed service levels.

At the core of the conflict is a mandate that requires freight railroads to give passenger trains access to rail track and preference over other rail traffic. A federal board is weighing the fate of Gulf Coast passenger service in a triallike process pitting Amtrak against freight railroads. Because Amtrak operates mostly on tracks owned by others, the case could set precedent as the passenger railroad embarks on a $75 billion expansion with bipartisan support.