study for how elevated highways divide neighborhoods and contribute to urban blight.) The phrase Interregional Highways gave way to Interstate Highways in a Congressional bill in 1944, and included $125 million for urban highways. The lead agency, the Federal Public Roads Administration (PRA) worked with state engineer associations to develop planning and design criteria. The PRA's leaders, especially Thomas H. MacDonald and Herbert S. Fairbank, were especially concerned about urban highways. Design standards were issued, with some opposition, which were significant improvements over existing designs. For example, minimum lane width of 12 feet and with a median of at least 4 feet (later standards would increase median sizing), minimal overpass heights were set at 14 feet, recommendations to acquire right of way sufficient for proper ramps of 3° great or less, right-side exit only and only to arterial connections. The Interstate standards have set the pace in the United States for optimal highway design, including those of elevated highways. Today Elevated expressways are now common around the world, particularly in the central urban areas where traffic volumes and urban densities are high such as cities in the Americas, East and Southeast Asia. Entire networks of elevated expressways exist in the central areas of cities such as Metro Manila, Guangzhou, Bangkok, Osaka, Shanghai, Tokyo, and Wuhan. See also Elevated railway References Types of roads