The Steel Bridge captures the engineering genius of John Lyle Harrington, who created the mechanisms that translated J. A. L. Waddell s pioneering vertical lift bridges into solid, reliable structures. It survives in part because Harrington refined both small components, such as the equalizers that distribute weight among the ropes and the guides that keep the spans in alignment as they move, and large features, such as the telescoping vertical member and the system of ropes, sheaves, and counterweights. Decades after its completion, engineering textbooks consistently portrayed it as exemplary.
Many original components tell additional tales as the bridge lifts and lowers.
Band brakes with an oak block wearing surface smell like a barbecue when a new operator trains, revealing, by contrast, the skill of experienced men who cut the motor at the right moment and allow the bridge to coast to a stop. The bridge operates through the friction of metal against metal, so the right moment varies from day to day and hour to hour as the weather changes and the oiler makes his rounds. Heat, for example, expands metal, but also softens grease, making the bridge run faster. The oilers let us in on an important reality when they say the bridge runs on grease . Knowing how much grease is also an art.