Page:America's Highways 1776–1976.djvu/488

 generally on new location. Only about 400 miles, or about 1 percent, of the System remained in a no-progress status at that time.

With the changes in statutory engineering requirements (20-year traffic projection (1963), minimum design of four lanes (1966), and increased System length by 1,500 miles (1968)) for the Interstate System, there were also legislative requirements enacted by the Congress in recognition of the public need in areas of economic, sociologic, and environmental considerations. Included in this category of legislative requirements were:


 * Assistance for relocating families and businesses—1962
 * Transportation planning requirements in urban areas for joint modes—1962
 * Scenic enhancement provisions, spot safety improvement program—1965
 * Joint development concept, soil erosion control, preservation of parklands—1966
 * Fringe parking facilities, increased relocation assistance, replacement housing—1968
 * Exclusive or preferential bus lanes, highway traffic control devices, passenger loading areas to serve bus and other mass transit passengers—1970
 * Urban mass transit provisions involving the withdrawal and substitution of certain Interstate routes in large urban areas—1973

The provisions of the 1973 Act have not yet been fully implemented, and the ultimate cost effect of this legislation is not known.

Such changes have a marked effect on the cost of constructing a highway system. This had been expected from the start. The earliest reports to Congress on the need for an interregional highway system stated the “impossibility” of venturing an approximate estimate of the cost of building the entire interregional system to the standards recommended. It was stated that to be of value, such an estimate would have to be predicated on far more exact determination of all variables involved than had been possible to undertake. Further, the Congress was informed that even had such precise determination been attempted, the “usefulness and validity of an estimate of the ultimate cost of a construction program that must inevitably extend over a period of perhaps 20 years and be affected by unpredictable changes in the general economy, in the habits and desires of people, in the character of vehicles, and in other circumstances, would still be highly questionable.”

With safety for the pedestrian in mind, a 1,082-foot long pedestrian overpass was built over I-95 in Shirlington, Va., that safely connects a large apartment complex on the east side of the highway with a large shopping center on the west. 482