英語翻譯
A goverment study recommended a national highway systerm of33,920 miles,and congress passed the Federal-Aid Highway Act of 1944,which called for strict,centrakky controlled desert criterra.
The interstate highway system was finally launched in 1956 and has been considered as one of the greatest public works projects of the century .To bulid its 44,000-mile web of highways,bridge.and tunnels hundreds of unique engineering designs and solutions had to be worked out.Consider the many geographic features of the country：mountains,steep grades,wetlands,rivers,desorts and plains.Variables included the slope of the land,and the ability of the pavement to support the load.Innovative designs of roadways,tunnels,bridges,overpasses,and interchanges that could run through or bypass urban areas soon began to weave their way across the country ,forever altering the face of American .
Long-span,segmented-concrete,cable-stayed bridges such as Hale Boggs in Louisiana and the Sunshine Skyway in Florida,and remarkable tunnels like Fort Mchenry in Maryland and Mr.bakerin Washington developed under the nation's physical challenges,Traffic control systems and methods of construction developed uder the interstate program soon influenced highway construction around the world and were invaluable in improving the condition of urban streets and traffic patterns.