Application of AASHO road test results to design of flexible pavements in Minnesota: 1964 Agreement

Investigation 183 began in April, 1963, with preliminary selection, of flexible pavements in each Construction District of the Minnesota Highway Department. Projects were selected where it was thought that well-defined
design occurred and a good traffic history could be obtained. With the aid of the district soils engineers, the areas were checked for uniformity and forty-one test sections were laid out. In 1964 an additional nine test sections were set up, bringing the total to fifty.

During the summers of 1963 and 1964 three phases of field work were completed on each test section, These were: (1) fractional plate load testing with in-place moisture and density determination of each layer and with samples of materials taken from each layer for laboratory testing, (2) determination of Benkelman beam deflections, rut depth, and cracking for each section, and (3) determination of the roughness index for each section. A second set of beam deflection tests has been run during the fall periods. Item (1) was conducted only once on each test section, i. e. on the original 41 sections in 1963 and on the nine new sections in 1964. Items (2) and (3) were conducted on all test sections in both 1963 and 1964. It is planned to run deflection and condition tests on each of the test sections on a periodic basis about once a year. The roughometer index is used along with the rut depth and cracking to determine a Present Serviceability Index as shown in Part V of this report. The trend of the PSI with traffic will define the performance of the test section.