LIFE CHARACTERISTICS OF SURFACES CONSTRUCTED ON PRIMARY RURAL HIGHWAYS

LIFE CHARACTERISTICS OF VARIOUS SURFACE TYPES CONSTRUCTED ON PRIMARY RURAL HIGHWAYS WERE DETERMINED FROM THE ANALYSIS OF CONSTRUCTION AND RETIREMENT MILEAGE DATA OBTAINED BY SEVERAL STATES IN CONNECTION WITH THE ROAD-LIFE STUDY PHASE OF THE STATE-WIDE HIGHWAY-PLANNING SURVEYS. APPROXIMATELY 210,000 MILES OF CONSTRUCTION UP TO JANUARY 1, 1937, OF VARIOUS SURFACE TYPES IN 26 STATES WERE INVOLVED IN THE ANALYSES OF AVERAGE SERVICE LIVES. IN ADDITION, AN ANALYSIS WAS MADE OF THE DISPOSITION OF MILEAGE AT THE TIME OF RETIREMENT, INVOLVING SLIGHTLY OVER 56,000 MILES OF RETIRED SURFACING IN 23 OF THE 26 STATES. ESTIMATES OF AVERAGE SERVICE LIVES WERE OBTAINED FROM STATISTICAL ANALYSES INVOLVING THE USE OF SURVIVOR CURVES. DATA WERE AVAILABLE FOR SOME TYPES AS EARLY AS 1903 AND A CONTINUOUS RECORD OF THE MILES REMAINING IN SERVICE FOR EACH YEAR'S CONSTRUCTION WAS AVAILABLE UP TO JANUARY 1, 1937. EACH YEAR'S CONSTRUCTION WAS ANALYZED SEPARATELY, WHERE POSSIBLE. IN GENERAL IT WAS FOUND THAT THE AVERAGE SERVICE LIFE OF THE LOWER TYPES DECREASED AND THE HIGHER TYPES INCREASED DURING THE PERIOD OF 1910 TO 1936. THE PREDOMINATING LIMITS OF AVERAGE SERVICE LIVES WERE AS FOLLOWS: (1) SOIL SURFACED, 5 TO 14 YEARS, (2) GRAVEL OR STONE, 6 TO 13 YEARS, (3) BITUMINOUS SURFACE TREATED, 11 TO 21 YEARS, (4) MIXED BITUMINOUS, 14 TO 22 YEARS, (5) BITUMINOUS PENETRATION, 15 TO 17 YEARS, (6) BITUMINOUS CONCRETE, 13 TO 20 YEARS, (7) PORTLAND CEMENT CONCRETE, 17 TO 24 YEARS, AND (8) BRICK OR BLOCK, 18 TO 21 YEARS. RETIREMENT OF A ROAD SURFACE IS CONSIDERED AS BEING EFFECTED WHEN (1) THE WEARING SURFACE UNDERGOES A RESURFACING OPERATION (OTHER THAN A ROUTINE MAINTENANCE OPERATION), (2) THE SURFACE IS RECONSTRUCTED, (3) THE ROAD IS ABANDONED, (4) THE ROAD IS TRANSFERRED TO ANOTHER PUBLIC AUTHORITY FOR CONTINUED MAINTENANCE AND RECONSTRUCTION, OR (5) THE SURFACE REVERTS TO A LOWER TYPE THROUGH LACK OF ADEQUATE MAINTENANCE. APPROXIMATELY 12 PERCENT OF ALL RETIREMENTS INVOLVED CONSTRUCTION ON NEW LOCATION. /AUTHOR/