In the last decade, the number of trucks on U.S. highways has risen from 4,590,000 to 8,200,000. Since the trucks themselves have grown bigger, the amount of freight carried has risen even faster, from 51 billion ton-miles a year to 115 billion. Has this enormous new traffic damaged U.S. highways and, if so, how much?
To find out, Ohio's Governor Frank J. Lausche got the highway directors of 16 Midwest and Eastern states to form the Inter-Regional Council on Highway Transportation. Last June the council started tests to measure the damage. Maryland set aside a 1.1-mile stretch...