COLUMBUS, OHIO - CSX Corp. said Thursday it will spend $300 million on upgrades to allow trains with double-stacked cars to run from the East Coast to the Midwest. Routes scheduled for improvements include the Carolina corridor from Wilmington, Del., to Charlotte.

For the effort to go forward, the federal government would have to provide an additional $400 million to change 70 overpasses in six states, including North Carolina, that are too low for double-stacked cars to pass under.

As evidence it is serious about the issue, the Florida-based railroad points to its plan to invest in two Ohio freight terminals that would handle the trains with taller cargo cars. Those terminals would be in North Baltimore in northwest Ohio and in Columbus.

The railroad says double-stacked trains use about the same amount of fuel to carry more freight faster.

"Interestingly, a lot of states are starting to realize more and more that some relatively small investments in rail infrastructure can be very cost-effective in relieving congestion," Michael Ward, CSX's chairman, president and chief executive, said in an interview.

The company's National Gateway project would prepare three major rail corridors in the eastern United States to handle train cars stacked boxes high.

Overpasses in six states -- Ohio, Pennsylvania, West Virginia, Virginia, North Carolina and Maryland -- would have to be adjusted to make the project happen, either by lowering railroad beds or by notching or replacing bridges, Vice President Lisa Mancini said.

CSX will invest $130 million in the two Ohio terminals, which would sit at the western end of the double-stacked network.

The Wood County facility would serve as a rail hub to points north and south, including Cincinnati and Detroit. Mancini said both will be built regardless of whether funding is secured for the entire project.

Freight and passenger rail traffic have been on the rise in recent years, CSX spokesman Robert Sullivan said, in the face of increased traffic congestion, deteriorating highway infrastructure and high gas prices.

The three rail corridors CSX has targeted with its effort are Interstate 95 between North Carolina and Baltimore via Washington, I-70/76 between Washington and Wood County, Ohio, via Pittsburgh, and the Carolina corridor between Wilmington, Del., and Charlotte.