It carries more passenger trains than any other railroad bridge in the Western Hemisphere, yet few people beyond those who rely on it have heard of it. It goes largely unnoticed, unless something goes wrong, which happens with irritating frequency. After all, the bridge is 104 years old.

Every time it swings open to let a boat pass is a test of early-20th-century technology that can snarl train travel from Boston to Washington, the nation’s busiest rail corridor. And over the years, because it is partially made out of wood, it also has proved to be quite flammable.

Read the complete story at The New York Times.