The adequacy of a pavement design is directly related to the accuracy of traffic data, axle load information and materials data. It is assumed that appropriate construction procedures will be employed and that the pavements will be maintained periodically during the course of their service lives.

It is assumed that the subgrade will be constructed at or near the optimum moisture content and to the maximum dry density as specified in appropriate standard specifications. It is also assumed that the base course materials meet design requirements, that the aggregates will meet soundness and durability requirements and that the aggregate base will be compacted to specified densities. Pavement layers should meet mixture design requirements and be compacted to specified densities. The construction process should be structured to provide as homogenous a pavement layer as practical within the limits of existing construction practices.

In the event it is not possible to construct pavements to meet design assumptions, pavement designs should be modified to reflect actual construction conditions. Most pavement thickness design procedures (including. the Kentucky procedures) are founded on the assumptions that quality materials will be used to construct the pavement, that appropriate construction conditions exist, and that appropriate construction procedures will be used. It is possible to develop pavement thickness designs for less than ideal conditions or for marginal materials. Examples of pavement designs involving marginal materials include those pavement designs wherein by-product (waste) materials have been used in one or more layers of the pavement structure. The level of pavement performance associated with a given thickness design also presumes some level of routine pavement maintenance. Designs may be modified to reflect other levels of maintenance such as the "zero maintenance" concept.

This interim design guide addresses only pavement designs presuming adequate subgrade construction conditions, appropriate construction techniques for aggregate and pavement layers, accurate information concerning the strengths and quality of materials used in the pavement, and accurate information concerning the magnitude and quantity of loads for which the pavement is designed to accommodate. Alternate design strategies should be used in the event these assumptions are violated.

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The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky nor of the Kentucky Transportation Cabinet. This report does not constitute a standard, specification, or regulation.