“Its importance to the national freight network is unquestioned,” Nadeau said. Funding remains elusive to replace the aging structure, a project that would cost an estimated $222 million.

An average of 32 trains a day, including Amtrak, cross the half-mile rail bridge that spans the Mississippi River just north of downtown St. Louis, according to recent numbers.

Regionally, rail carried about a quarter of all freight tonnage in 2012.

Big changes to Interstate 270 also are being sought, including widening the road to six lanes from four between Illinois Route 111 and Lilac Avenue, estimated to cost from $350 million to $400 million, and replacing its bridge over the Mississippi with a six-lane span for between $160 million and $175 million.

Infrastructure upgrades being called for go beyond roads and bridges.

Paul Jaenichen, administrator of the federal maritime administration, said Monday that the nation isn’t ready to handle the big ships of the future, citing aging and too-small ports.

Rhonda Hamm-Niebruegge, director of Lambert-St. Louis International Airport, stressed the importance of air cargo and the role that medium-sized airports with freight capacities can play.