page_title: Elevated highway
section_title: The Interstate system
hierarchical_section_title: Elevated highway / History / The Interstate system
caption_attribution_description: English: Elevated section of Interstate 81 in Syracuse, NY.
context_page_description: An elevated highway is a controlled-access highway that is raised above grade for its entire length. Elevation is usually constructed as viaducts, typically a long pier bridge. Technically, the entire highway is a single bridge.
context_section_description: In the mid-1930s, US Federal Highway legislation allocated budget for surveying and planning of roads, including "superhighways", across the nation, and ordered the chief of the Bureau of Public Roads to report findings and recommendations. The report, submitted in 1939, included a master plan, which recommended that urban highways be "depressed or elevated". In 1944, President Franklin D. Roosevelt submitted a follow-on report, Interregional Highways, which contained illustrations of the depressed and elevated designs. The elevated illustration, reminiscent of the Miller Highway and some of its descendants, featured partial left lane ramps, a highway running across the width a populated boulevard, almost building-to-building, a local traffic lanes underneath the highway. The report also includes a picture of the then-recently constructed Gowanus Parkway, and noted how it was thought to have been an appropriate placement that had a minimal effect on the community. (This was later disputed, and the Gowanus is also a case 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.
caption: Interstate 81 in Syracuse, New York State
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