Introduction

The airfield pavement includes runway, taxiway, shoulder and the apron. Some of the portions of these components are identified as critical areas , and some are non-critical areas . As a general guideline, the critical areas are those portions where the aircraft speed is low, or the aircraft is in rest. More thickness is required for the pavement in critical areas. In the non-critical areas, for example, the central portion of the runway, the air craft is partly air-borne; also due to larger lateral wander the stress repetitions at a particular spot is small (FAA 2006, PCA 1995). For high speed (i.e. small time of contact), the asphalt shows higher strength (creep modulus) than slow speed movement. Thus, design thickness for non-critical areas turns out to be less than the critical areas.

Same design chart is, generally, recommended for design of airfield pavements, and some factors are prescribed for adjustment of thicknesses for the individual components (i.e. runway, taxiway, shoulders and apron) of the airfield pavements.

Input parameters

The various parameters used in pavement design have already been discussed in the section 'design parameters' of the lecture ' various design approaches' . Similarly, the parameters involved in the airfield pavement thickness design process are the aircraft gear loading (gear configuration, wheel load, tyre pressure, lateral wander), load repetition, material properties (stiffness of individual layers, fatigue behaviour of bound layer(s)) and environmental factors (temperature, subrgade moisture).