High Speed Highways

United States

The idea for the U.S. Interstate Highway System dates back to a 1939 report (Toll Roads and Free Roads) to the U.S. Congress suggesting construction of a toll-free express highway network, and construction of such a national system of highways was authorized by the Federal Aid Highway Act of 1944. However, construction on the system did not begin until authorization of the Federal Aid Highway Act of 1956, signed into law by President Dwight Eisenhower (hence, the interstate system is sometimes called the “Eisenhower Interstate Highway System”). Roads in the interstate system are owned and operated by the states in which they exist, but in order to encourage construction, the federal government paid 90 percent of the costs and the states contributed 10 percent. The first section of the interstate to begin construction under [Page 696]the 1956 law was in St. Charles, Missouri, and in 1992, the system as originally planned was completed. However, roads continue to be added and improved. The Interstate Highway System currently comprises almost 47,000 miles of roads.

The interstate system was designed to facilitate safe, high speed vehicle travel. Interstates are limited-access highways, meaning that one can only enter or leave an interstate through a controlled exchange rather than by an intersection, as is typical of slower-speed roads. Federal regulations also specify the width of lanes (12 feet) and shoulders (10 feet), and maximum grade (3 percent), and stipulate that interstates must be designed for safe travel at 70 miles per hour. Minimum bridge clearance was originally set at 14 feet, but this was raised to 16 feet for new construction or reconstruction in order to facilitate the transportation of large military equipment. Pedestrians, bicycles, and other nonmotorized vehicles are not permitted on most stretches of the interstate, although in some states bicycles are allowed to travel on the shoulder.

In a 1954 speech, President Eisenhower outlined the purposes of the proposed interstate system; these included improving road safety, reducing road congestion, boosting the economy, and aiding military and civil authorities in meeting the demands of a catastrophe or military emergency, including an atomic war. The safety standard was certainly met; innovations in roads and automobiles as well as changes in laws (for example, much stricter enforcement of drunk driving laws today than in 1954) have made automobile travel much safer in general, and despite the high speed of travel on interstates, their fatality rate was lower in 2004 (0.8 per million vehicle miles traveled) than the average for all U.S. roads (1.46 per million vehicle miles traveled).

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