Well car

The "well" is a depressed section that sits close to the rails between the wheel trucks of the car, allowing a container to be carried lower than on a traditional flatcar.

This makes it possible to carry a stack of two containers per unit on railway lines (double-stack rail transport) wherever the structure gauge assures sufficient clearance.

Well cars are most common in North America and Australia where intermodal traffic is heavy and electrification is less widespread; thus overhead clearances are typically more manageable.

That same year, the first all "double stack" train left Los Angeles for South Kearny, New Jersey, under the name of "Stacktrain" rail service.

Also, in a number of cases multiple single-well cars (usually 3 or 5) are connected by drawbars and share a single reporting mark.

(The sizes of wells are frequently marked in large letters on the sides of cars to assist yard workers in locating suitable equipment for freight loads.)

Low bridges and narrow tunnels in various locations prevent the operation of double-stack trains until costly upgrades are made.