HIGHWAY NEEDS OF THE NATIONAL DEFENSE
15
The grade on U S Route 70 averages almost 11 percent for a distance
of 0.15 mile. The up-and-down hourly traffic on this grade in 1948
was 555 vehicles. The street has a 55-foot concrete pavement.
Photo by Norman G. Wallace
Such winding location, often pictured as evidence of good engineering, ignores the necessities of safe accommodation of modern traffic. This section of U S Route 66 in Arizona must be relocated to meet the interstate system standards. In total, 11,891 miles of the system require relocation.
The longest grade
The longest grade on the entire system is on U S Route 99, south of Bakersfield, Calif. It is 20 miles long and averages 4 percent over the entire length. Included, however, are two 6-percent grades, totaling more than 6 miles, and two 5-percent grades, totaling one-half mile.
