Manchester Bridge in Richmond, Virginia carries U.S. Route 60 across the James River.

The former Ninth Street ("Singing") Bridge was a primitive affair built rather low over the river, and whose creosote-treated wooden deck was fitted with strips of metal plates spaced a tire-track apart, to prevent excessive wear.

As the tires rolled along, these plates, embossed to provide traction, would give off a high humming note—one that suddenly would rise by about a fifth as a vehicle crossed from south to north: presumably the embossed pattern changed at that point.

The former Ninth Street Bridge was closed and barely escaped submergence during river flooding resulting from Hurricane Camille in 1969, strengthening the resolve of engineers that the replacement would be high above even flood levels of the river.

[1] When almost completed, it was pressed into temporary service earlier than planned during James River flooding as a result of Hurricane Agnes.