Referred to as the “Mixing Bowl,” the I-395 interchange at the Pentagon was considered a colossal undertaking. It sorted traffic from seven highways with 38 bridges and 32 lane separations. Although Virginia’s Springfield Interchange improvement effort has exceeded this project in size and has claimed the same “Mixing Bowl” title, in 1970 the I-95/I-395 interchange was considered the largest ever constructed in the U.S. The effort took $90 million and six years to complete; it was finished in 1973. I-395 became one of the first interstates in the country to include high-occupancy vehicle lanes.
At its completion in 1969, some I-395 lanes in Northern Virginia were
reserved for express buses. Later, the bus lanes opened to carpools,
creating some of the first high occupancy vehicle (HOV) lanes in the country.