Miriam's Bridge

A creek runs between Miriam’s country home and the road to town. She has to park her car and, clutching bags of groceries, scramble down and up steep embankments. During thunderstorms, high water sometimes cuts her place off from the rest of the world. Many Mexicans develop their property poco a poco—a little at a time—as money becomes available. Now that her house and casita are finished, Miriam is building a bridge to improve access. Much of the work had been completed when we visited: only the deck and parapets have yet to be installed before she can drive across it. Here, Miriam and Laura pose, lending scale to the project.

Arched stone bridges have been built since the iron age. A 3,000 year-old example is still in use in Greece today. Miriam’s bridge is built of undressed stones so they have to be mortared, which accounts for the thick columns. The construction utilizes one 20th-Century innovation: steel rebar strengthens columns and spans.

Semicircular arches compress stone when the bridge is under load, strengthening the spans. Ramp-shaped structures on the upstream side deflect water and flood debris, shielding the columns from erosion. Function dictates the shape, yet makes a form that is esthetically pleasing.

An old wall was quarried to build the bridge. Local masons mold irregular rocks into rectilinear planes, a skill I admire. That the land itself provides construction materials is somehow satisfying. The bridgeworkers are descendants of the builders of Teotihuacan. I visualize ancient construction methods being handed down through centuries—a not-unreasonable explanation for the high level of masonry skills prevalent in Mexico.