Jacob Haas

Highway Geometry: Hale’s Postcard from Buenos Aires

Engineer Arthur Hale designed America’s first cloverleaf interchange in 1929 after seeing a sketch on a postcard from Buenos Aires. Arthur Hale and later engineers examined how to move vehicles without stoplights, eventually leaving behind the "ghost ramps" of San Francisco’s 1959 Highway Revolt. These concrete structures dictate human behavior through the physics of the 20 km/h phantom ripple and the calculated safety of sand-filled Fitch Barriers at the highway gore point. Modern innovations like the Diverging Diamond Interchange in Springfield, Missouri, revealed new ways to reduce conflict points for millions of daily commuters.