Episode 12: Where Roads Cross: The Hidden Engineering of Highway Interchanges

Ever wondered about those massive concrete structures where highways loop, merge, and stack on top of each other? Tonight, we're exploring the surprisingly fascinating world of highway interchanges—the engineering marvels you've driven through hundreds of times without a second thought.


Discover the elegant cloverleaf designs of the 1920s, the towering five-level stacks of modern cities, and the innovative diverging diamond interchanges that briefly move you to the "wrong" side of the road. Learn why early traffic engineers faced a critical problem: how to let high-speed traffic cross paths without anyone stopping, and why their solutions—from New Jersey's pioneering cloverleafs to Los Angeles's billion-dollar spaghetti junctions—shaped American cities and suburbs.


We'll explore the "weaving problem" that plagued early designs, the controversial legacy of builder Robert Moses, and what the future holds for these monuments to automobile culture in an era of autonomous vehicles and changing transportation priorities.


Perfect for curious minds who love learning about the hidden complexity of everyday infrastructure. Settle in and drift off as we unravel the loops, levels, and logic of highway interchanges.


Dormant Knowledge is the educational sleep podcast for curious minds. Learn something fascinating while you fall asleep.


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