"To free Kentucky of slick roads" is the high goal toward which Kentucky has been striving since 1950's. A very capable fellow engineer used to say that there was more satisfaction in being able to take down a Slippery When Wet sign than in erecting one.

Considerable effort has been devoted to the development and adaptation of improved methods of skid resistance testing and to the standardization of testing devices (1, 2, 3, 4). Methods of tests have included the NCSA friction wheel (bicycle wheel), automobile deceleration, skewed-wheel (skewed front-wheels of an automobile), skidding automobile, and the skid-test trailer. The development and standardization of a trailer method of test in recent years represents significant progress in the measurement area.

From the outset of our skid resistance measurement program, evaluations of pavement design, construction and maintenance practices were of utmost concern. In fact, the first field tests -- made in 1953 -- resulted in changes of the design mix in the use at that time (5). Every type of pavement and sealing and deslicking treatment used in the state have been monitored and assessed as to their friction properties (1, 6, 7). Insights gained have been applied towards the development and refinements of wearing surfaces.

Skid resistance standards for maintenance and mix design purposes must be established if meaningful improvements in highway safety are to be realized. Arbitrary judgements as to minimum requirements will not suffice because the safety and economics involved are much to important to every highway user. Efforts to derive minimum skid resistance requirements in Kentucky were based on accident statistics. Critical values have been determined for rural, four-lane, controlled access roads (interstates and parkways) (8). Critical values for rural, two-lane roads (U.S. routes) are forthcoming.

Studies of pavement slipperiness have received renewed emphasis as a result of attention directed towards highway safety. Congress recognized the element of pavement skid resistance in the Highway Safety Act of 1966 and the resulting Highway Safety Program Standard !2, dated June 27, 1967. Most recently, Instructional Memorandum 21-2-73, dated July 19, 1973, stressed the importance of pavement skid resistance in providing safe highways. Kentucky has continued to progress in this vital area.

Report Date


Report Number

No. 399

Digital Object Identifier



Prepared for presentation to the 33rd Annual Meeting of SASHTO, October 16-19, 1974, Louisville, Kentucky.