Rail freight traveling direct between most of New York City or Long Island and all points south must take a 280-mile (450 km) detour along the Hudson River and across the bridge, a route known as the Selkirk hurdle.

Rail freight may also reach Long Island indiectly via the NYNJ railroad's car float over New York Harbor, but the capacity is extremely limited.

The Alfred H. Smith Memorial Bridge was completed in 1924 to facilitate rail freight traffic, which was growing increasingly bottlenecked through Rensselaer.

[3] Steep grades west of Albany required delays of westbound traffic as additional engines were supplied or trains were broken into multiple sections to allow them to climb the hill.

[3] But, backed by Alfred H. Smith, the future President of the New York Central Railroad, contracts were awarded in 1921, with Walsh Construction Company receiving the bulk of the business.